The White Lightning 818e thread

[Speedy G]

Finally my first parts came in so I can say that my build started. This build is a pretty radical one since I'll essentially be putting a square peg into a round hole and I'm most probably biting more than I can chew, but what fun would it be if I didn't. The budget is unknown, and I'm not going to talk about it since I'm building my personal supercar so the dollar sign just went out the window.

So why White Lightning? It's my donor:

34687

I bought the drivetrain for the original white lightning and I'm putting it in an 818s. The car originally did 0-60mph in 8 seconds and had a top speed of over 300mph, although its bonneville official record was 245mph in 1999. The white lightning car weighed 2,550lbs and I'm hoping to brind that weight down to less than 2,400lbs in my build because of the use of different battery technology. Ed Dempsey's team used belt drive between the two motors, and hooked them up directly to a 9" Ford rear axle, no tranny.

What I'm doing:

1) Use the original belt drive setup for the dual motor setup (yes I know, not efficient and at 10,000 RPM it's way over the belt spec). The motors are AC Propulsion Generation 1, 150KW each (200hp). The motors were tested by AC Propulsion and yielded 165KW @ 350V or around 218 hp each. Ed's team modified the motors for better cooling, which suits me fine.

34688

2) One of the original motor controllers has broken IGBTs so I'll need to replace them. This will mean redoing the power electronics since the original IGBTs cannot be bought anymore. I don't think it should be too difficult since IGBT technology has advanced considerably since the 90's, so an off the shelf IGBT should easily replace the original ones. The idea is to initially register the car with 1 of the controllers (so 218hp). The controllers are also so big that I may consider redoing the housings. They're that big because they're air cooled, so using a water cooled housing should make them significantly smaller. Also the original IGBTs are discrete which makes them at least twice as big as today's dual IGBT modules (hi +lo). All that means is there's potential for lowering the weight and size of the controllers.

** I decided to go ahead and start experimenting so I ordered some IGBTs. I went with the newest generation of Powerex IGBT MOD NX 600A 1200V DUAL and their VLA536-01R driver board. That pretty much means I can hook up a cpu directly to 3 of those and dump 600A @ 1200V (~960hp) into a resistive load (I can smell the burnt chip smell already!). I just don't want my electronics underdelivering. Btw, that's for 1 of the motors.

3) Batteries - Erik's build used 50 100Ah CALB batteries, I'm thinking 100-120 are required for my build. Where to put them??? We'll see, probably in the back, maybe some in front of the axle (ugh). That I have to do when the car gets in to see where they fit and where I can fit the electronics (currently the size of a medium fridge).

* Update - The batteries will be 110 CALB CAM72FI for the standard controller and 110 A123 20Ah pouches for the acceleration controller (added later). The initial pack fits 70 batteries in the center tunnel and the gas tank location and the rest on either side of the motors and tranny.

4) Gearbox - The main design issue. How to hook up the motor to a tranny? What tranny? The ideal EV tranny is very different from a regular tranny. First, my motors can go to 12,220 RPM (tested by AC Propulsion). Second,due to the high RPM and torque curve, the car can accelerate like an M5 from 0-62mph in first, while an M5 has to go through 1st and second, so I need less gears (3 is probably ideal). Third, since I can control the motor speed very precisely, I can shift into neutral from any gear, rev match and shift to the next gear. That means I don't need synchros or a clutch. There's companies that have built EV specific gearboxes that shift like this in less than 100ms, which makes them as fast or faster than ferrari or BMW dual clutch boxes. So... what to do... If I can get a cheap subaru donor I might try to use it, otherwise, a full sequential is my first pick (PBS S4 (http://http://www.weddleindustries.com/transaxles/pbs-transaxles/pbs-s4s5h4) ).

** Update - I'm going with a subaru tranny just because it fits easily. I won't be running a clutch, just a straight shaft from the motor assembly to the tranny input shaft. Initially I'll run the car in 2nd gear only since it's close to what tesla runs in their Borg-Warner setup. With the 3.9 final drive 2nd has a total ratio of 8.04, which should be fine for city driving. We'll see if it's worth changing the final drive later. Later, I'll automate the shifting with a modified mastershift paddle shifter. Top speed in 2nd would be 150kph (94mph) at 10,000 RPM or 180kph (112mph) @ 12,000 RPM (if the tranny can handle it). Maybe I'll have to do something to the lubrication system of the tranny, we'll see.

5) Shopping list (bought so far)-

2015 STI steering Rack - Flatirons tuning
Aluminum LCA - Flatirons tuning
Wayne's Rear Trailing Arms - verycoolparts.com
Engine cover hinge - Michael Everson
Hood hinge - Mechie3
Speedometer/Odometer - Stack ST3802
Tachometer(13kRPM)/multi-display - Stack ST700SR-N
Fuel Gauge - Stack ST3315
TCI Paddle Shifters 301441
Wilwood hard brake lines Frnt & Back
Sparco L360 Steering wheel
Sparco Steering wheel hub adaptor -STRWL HUB SUBARU
Sparco Steering Wheel Ring - black

EV parts:
Gigavac GV200-MA EV Contactor
Gigavac Maintenance Switch HBD41AA
Brake Pressure Transducer for Regen - 5 Volt - 1000 psi
ZEVA Fuel Gauge Driver Plus
High Voltage Fuse 500 Volt 400 Amp A50QS400
High Voltage High Current PolyCarbonate Fuse Holder P243G G Type
Prius Gas pedal - EV West

Tools Bought:
Bosch PS10-2A driver/drill
Campbell Hausfeld Commercial CL153900AV Rivet Gun
Grinder - Dewalt 5"
Dremmel multimax MM40
Cobalt Drill Bits 19/64", 1/8" - Century Drill
Cobalt Drill Bits 25/64" - Bosch
Cobalt Drill Bits 5mm - Cle-line
Torque Wrench 3/8" 60-960 in lbs - Titan Tools 23147
Torque Wrench 1/2" 25-250 ft lbs - K-Tool 72102


Let the games begin!

Speedy G

[Bob_n_Cincy]

Hey Speedy
Great to see another electric 818.
I am pretty familiar with the AC Propulsion controller and motor. I raced against them back in the late 90's.
Some evening I could have a long phone call information dump.

Take a look at these links. The tZero was built by the founder of ACP Allan Cocconi. It is similar size to the 818. It started as a kit car by Piontek engineering. Piontek used a motorcycle engine.

Just a bit of history. That motor and controller was the start of Tesla.
Bob

https://www.google.com/#newwindow=1&q=Tzero


http://piontekengineering.com/

[Speedy G]

Yeah, exactly. I was fortunate to talk to Paul Carosa about the motors. He was a bit skeptical due to their age, but he did some maintenance and sent me most of the literature. High RPM induction motors are it, the only problems are the gearbox and the high voltage.

Bob, I'm sure you could teach me a thing or two about batteries. What kind of batteries does the lightning bike have? How do they fit a 20kWh on a motorcycle? I'm trying to fit 30kWh into the 818! Any info on the battery front would be awesome. Btw, did the AC Propulsion guys beat you in the 90's?

Also, on the gearbox front, any info would be greatly appreciated. Here's a pic of what I have to hook the gearbox into:

34691

Any idea what kind of splined shaft hooks up to this and where I can get it, or how I could hook up a subaru tranny straight to this? Remember, I don't need a clutch or flywheel. I'll probably be using a mastershift paddle shifter, so shifting can be done without a clutch. The trick is to do the shift without power on the motor, and rev match to the new gear's RPMs.

Speedy G

[Bob_n_Cincy]

Bob, I'm sure you could teach me a thing or two about batteries. What kind of batteries does the lightning bike have? How do they fit a 20kWh on a motorcycle? I'm trying to fit 30kWh into the 818! Any info on the battery front would be awesome. Btw, did the AC Propulsion guys beat you in the 90's?



Hi Speedy,
Lithium-Ion Prismatic Cells. I don't know if we publish the brand name.
Very Expensive high power batteries. Only 1/4 of a tesla 85kw.

I had 4 cars running my controller and Allen had 3 cars.
Ohio State (ACP) and BGSU (EMS) were the 2 fastest cars. I remember (selective memory) that winners were about 50/50.
There was one race I did not attend and we got all three podium spots.
I need to get that picture for my scrapbook.

Here is a quick story about the Formula Lightning Series.

http://www.roadtripamerica.com/wheels/flc.htm

[Frank818]

Speedy!! Finally yes! :) Wow I didn't know you bought a rocket as a donor! The drivetrain, but you need a great drivetrain to build a rocket, right. :)

Much different than the VR6, but still similar level of challenges, more or so... Keep us posted, we want to see things moving!



I raced against them back in the late 90's.

And? Who won? :)

[Speedy G]

Since I'm still in the R part of R & D, I thought I'd write an update on alternative drivetrain solutions. Why? Because I looked at pretty much everything under the sun in order to optimize my setup. The short story is that I'll be using a regular 5MT tranny. We'll see if it can do 12,000 RPM though.

So an EV... What is the best tranny for a high rpm EV like mine or a Tesla? Single gear? Not really. First, at 12,000 RPM you're only going at 108mph. That's hardly sports car territory. Second, induction motors with sensorless vector controls are VERY inefficient at low RPM. Here's a Tesla range/speed graph, which can be thought of as an overall efficiency graph as well:

35417

Now if we want to see what "inefficiencies" are important at what speeds, here's another graph:

35418

Notice the drivetrain has some serious inefficiencies below 10mph.

So what would be the ideal gearbox for a high RPM motor like mine? Has anybody made one? Sure, and it's as good or better than BMW and Ferrari's dual clutch stuff, and simpler, and it's made for trucks!!!


https://www.youtube.com/watch?v=TXQGw7S-xOU

Wrightspeed.com (http://wrightspeed.com/products/the-route/#features)

Notice that it switches from first to second gear in 80ms (like the BMW dual clutch tranny). Btw, that's 80ms switching from over 20,000 RPM to 9000 RPM. However, it doesn't wear out because it doesn't have any clutches or synchros!! It's a dog box! What happens is the electric motor can be manipulated to exert 0 torque so the gear can be disengaged, then the motor recovers rotational energy from the motor by making it go from 20,000 RPM to 9,000. Once the motor and tranny's second gear are speed matched, the motor again exerts 0 torque, and the dog engagement shifts into second, gear. Once the gear is in, full torque is available again. Oh, also that's a clutchless shift.

So what would be the ideal ratios for an EV? Well, first is limited by traction. Remember I have 330 ft lbs from 0-6000 RPM, flat. So I chose first to be at the limit of traction ( ~13:1 - 14:1). Next, I'd chose third to give me my top speed, say 200mph at 12,000 RPM (so 4.5:1). Next, I'd chose second, although unnecessary, but it may give me better driveability at highway speeds and maybe improved efficiency. I chose 6.86 since that would make the shift points even (105 kph, 210 kph and top speed of 320kph). Why such wide ratios? I have full torque down low, so the lower the RPM that I can shift into, the better. Also comparing to an M5, my first gear will have better acceleration than the M5 in first AND second at peak torque.

So that's it for ideals. What's really available? I looked at the following:

Powerglide - 2 gear, can be modified for manual shift, direct drive (no torque converter). Can be directly coupled to a Ford 9". The powerglide is light, but the ford 9" is really heavy. Also the setup ends up being way too long before the axle centers. The shifting action is also extremely harsh, so not really a street car tranny.

C5 transaxle - Heavy, Ratios kinda suck, scarce. C5 guys said I'd be better off with a Ford 9".

Porsche G50 - Original car was rear engined so you have to turn it upside down and do some minor changes to the diff so it drives the right way. Frank is trying to make it fit with his VR6. It's hard to find a good one.

Porsche G86.20 - Boxter tranny. This will probably fit, but it'll probably push the engine further to the front a bit. The tranny is strong and may be a good candidate, but I haven't found any reasons to use it to replace the standard subie 5mt, in stock form it's probably as strong as the subie tranny, and uprated gear sets are very expensive. This tranny will probably push the engine forward a bit, like 2 inches.

PBS, Medeola, Albins, Weddle or Vw Transaxles (http://weddleindustries.com/transaxles) Some of the mentioned ones are sequential dog boxes. Only the sequentials seem to be stronger than the subie trannie. The sequentials provide no real benefit for an ev if rev matching is implemented in the control, like the wrightspeed box. These transaxles would move the engine forward quite a bit, probably up to 6 inches, which might be ok in an EV. These transaxles start at USD7k and got up to over USD15k. I'd only consider one if I were a hardcore racer, and for that, I like the 4 speed PBS sequential with helical gears.

Subie 5MT - Ratios are: first is 13.5, third is 5.85 and fourth is 4.24 - If I get a 4.11 final drive, then first is 14.2, third is 5.95 and fourth is 4.47. First and fourth are perfect for my ideal situation, fifth is useless, but I have second and third to choose from for highway driving. However, cooling the oil doesn't seem to be an option. The big advantage, the frame is built for it. Paddle shifting can be done using a modified mastershift system and rev matching using the drive and control system. The clutch can be a low MOI clutch. I'm currently looking at a tilton 5 inch tripple disc clutch. I need something that can hold at high rpm. Whatever it is, it'll have to be modified. Eventually, if the control system is good enough, maybe I can do without a clutch altogether.

So my only question is, is someone that's pushing 300whp having serious problems with traction or is it manageable? What tires? What ratios?

[Frank818]

Porsche G50 - Original car was rear engined so you have to turn it upside down and do some minor changes to the diff so it drives the right way. Frank is trying to make it fit with his VR6. It's hard to find a good one.

True. And I am a couple of days of seeing it fit or not. I just received the adapter plate and stuff. Gotta fab a shifter bracket kit as well and having in mind now that shifting also works upside down. But it's strong enough no issues and has the possibility to use a lot of different ratios per gear. My mechanic has a second one, but maybe not in such an excellent condition mine is.

I wish I could tell you how it runs with 400whp but I can't until late next spring or early summer.

[Speedy G]

Yeah, but your torque is gonna be way more than 330 ft lbs. You're gonna be burning rubber in second. I have a traction advantage stemming from around 400 lbs worth of batteries in the back plus hopefully less than 320 from the motors and controllers. By modding the controllers I should be able to shave at least 70 lbs off the drivetrain weight. That's a target of 650 lbs vs 270 from the subie motor. For comparison's sake, your VR6 is around 420lbs.

Btw, for those that aren't building from donors, it seems like the 2015 STI steering rack fits. The advantage is a ratio of 13:1 vs 15:1 for regular wrx or 18:1 (I think) from a forester. In my case, that means leaving the power steering, essentially for low speeds. I'll be using an electic motor as the power steering pump. That also means I could control to a point how much power assist I have at any speed with an additional simple control system and a driver (mosfet of sorts).

[Frank818]

Speedy, where are you in the build?

[Speedy G]

There's updates up on the first post btw. I'm still in the design stage since the kit hasn't arrived. My date was the 27 of Dec, but in this holiday season it's hard to arrange everything. Banks and my shipping company as well as FFR have days off, etc. I'm thinking I'll get the kit in mid-february at this pace. I've solved several issues though. I now know that I can register the car here in Colombia as long as I register my company as an automotive assembly plant, and therefore I can say what model year the car is. The process will be long, but I can start it once the car drives but there's a ton of post initial drive projects that I can be doing while the whole legal stuff gets sorted out. Here's a short list:

1) Replace the monstrous power stage of the AC propulsion drive with my modern day design - Powerex IGBT MOD NX 600A 1200V DUAL + driver board + snubber capacitors + water cooling. This alone should shed maybe 15 lbs and use less power than the air cooling system the original power modules had.

2) Battery management system - I'm thinking of using a battery management system just so I an keep track of the battery voltages. I plan to abuse the batteries to 10C (1C would be a discharge rate of 30kW/h), so keeping track of failing batteries is probably a good idea.

3) Main control system - I'll be using a Cubietruck (ARM based computer) as the main entertainment and control system of the car. It'll have 500G of solid state hard drive, and run some flavour of linux.
3a) It'll be connected to a DAC which in turn will be connected to a power amp using balanced connections. My cell phone will also connect to the cubie so I can use music on my phone over the car stereo.
3b) It'll control the power steering pump. Less power steering as speed goes up. The power steering pump is electric btw.
3c) It'll control the vacuum pump for the brakes. I'll be using computer controlled power brakes. Another electric pump will provide the vacuum to power assist the brakes. You gotta remember this thing will weigh in at around 2300lbs when I'm done.
3d) I'm thinking maybe I'll have some power ventilation in the car. If I do, the cubie would also control that.
3e) The cubie will have either a 7" or a 9" touchscreen built into the center console. So I imagine I'll have to develop some software to display the control options as well as various sensors (water temp, motor temps, battery temps, total current used, kwh/km, battery voltage, etc). I'd also like to have google maps and a wifi connection through my phone.

4) Automate the tranny with a modified mastershift shifting system since I'm running a directly coupled motor to tranny. The mastershift workflow needs to be altered to shift, like this: run-> depower motor-> neutral-> rev match-> shift-> repower motor.

5) Redo all the fibreglass parts in carbon fiber. There's a local guy that works on racecars that makes the carbon fiber molds. I should be able to shed quite a bit of weight with this mod. Locally it's not as expensive as it would be in the US.

But then again this is all still vaporware since I haven't turned the first screw yet...

[Frank818]

Oh it's not there yet, sorry I thought it was. It'll miss New Year's, but it gives time to design.

Very cool stuff, lots of non-FFR stuff! Actually, your build will be way more complex than mine. You have will, the 2nd strongest power in the Universe. :) How long you estimate to build everything?

[ninjanick]

SpeedyG,
Have you laid out your traction pack yet? I'm still in the middle of figuring out the best layout for my build.

[Gary Livingston]

Hey Speedy!
Wow! a very ambitious project. I thought the White Lightning was in a museum somewhere. I'm building electric also so I will be following your thread closely as well. :)

Regarding C rate mentioned below......


2) Battery management system - I'm thinking of using a battery management system just so I an keep track of the battery voltages. I plan to abuse the batteries to 10C (1C would be a discharge rate of 30kWh), so keeping track of failing batteries is probably a good idea.

C rate is actually a discharge rate relative to cell Capacity. So, 1C for 100Ah cells would be 100 amps. 10C would be 1000 amps.
Ah and kWh are both measures of energy. Ah usually used for individual cells and kWh usually used for packs. WH (watt-hours) are a more accurate measure of energy than Ah (amp hours) because they take into consideration the voltage and current, not just the current.
So, a pack consisting of 100 pcs of 100Ah cells (if LiFePo4 chemistry) would have an energy capacity of 3.2 (cell nominal voltage) x 100Ah x 100 units = 32,000wh (watt-hours) or 32kWh.

To determine how much horse power you could get from this pack, you would need to know the voltage level at the specific current level. Lets say at 1000 amps, cell voltage would sag to 2.5vpc (volts per cell) x 100 cells x 1000amps or10C. That would be 250,000 watts or 250kw.
250,000/746 = 335HP
If your drive train was 90% efficient, you would have 300hp at the wheels.

Sorry, got a bit carried away there. Was just going to correct the C rate. . . but thought some folks may benefit from the explanation.

[xxguitarist]

Speedy,
On the BMS front:

Will you be running active, passive, or manual charge balancing? It's a big thing with lithium cells to maintain good balance. Depending on the chemistry, it varies from detrimental to performance.. up to dangerous, to have mis-balanced cells. It can lead to over discharge and over-charge events.

What is your plan for battery cooling? At high C rates, the cells generate a bit of heat, again depends on chemistry some. On the other side, what about heating, or will the car not be driven/charged if it's below 40F?

Charging? Only at home, or perhaps with J1772 Level 2 or the more recent DC fast charge CHAdeMO etc infrastructure support? The former isn't too difficult to implement, it's a relatively simple handshake process.

[Gary Livingston]

Speedy,
On the BMS front:

Will you be running active, passive, or manual charge balancing? It's a big thing with lithium cells to maintain good balance. Depending on the chemistry, it varies from detrimental to performance.. up to dangerous, to have mis-balanced cells. It can lead to over discharge and over-charge events.

What is your plan for battery cooling? At high C rates, the cells generate a bit of heat, again depends on chemistry some. On the other side, what about heating, or will the car not be driven/charged if it's below 40F?

Charging? Only at home, or perhaps with J1772 Level 2 or the more recent DC fast charge CHAdeMO etc infrastructure support? The former isn't too difficult to implement, it's a relatively simple handshake process.

The topic of BMS or not has been a hot one on several forums for quite some time. Enough years have passed now with enough experience and data to prove that LiFePo4 does not need to be actively balanced. I subscribe to manually balancing, preferably bottom balancing, and not exceeding a charge voltage of 3.6vpc. I actually charge to only 3.45vpc. The capacity above this point is not much and the life is prolonged with this approach. As long as you have a well balanced pack, this approach works well. I have been running this way for years on the older CALB SE cells, with no balance issues. I've also run a booster pack of A123 32157's the same way.
There are some caveats, such as having cells in the same pack exposed to different temps, as well as significant differences in capacities.
It is widely believed that most catastrophic fires are caused by BMS's failing to stop the charging process and overcharging leading to thermal runaway.
Other lithium chemistries seem to require a little more balancing care . . .but I'm not sure i would charge most of them at night in my garage... lol
I think a BMonS (monitoring) is not such a bad idea. . . BManS (managing, meaning top balancing) not so much required. Some folks have coined these systems Battery Murdering Systems... lol

Discharging is ok down to -20C typically for LiFePo4 although performance suffers greatly at colder temps. The real thing to avoid is charging below 0C. This will cause lithium plating and shorten battery life significantly.

cheers! :)

[erlihemi]

Speedy, Awesome project! If you can program for zero torque crossing at shift points, then any circle track 2 speed manual should be lighter than the powerglide. Why not just direct couple a subie CVT? then you have programmable torque/speed control potentially... You have a heavier 818 than design so contact patch can be increased and traction is less of an issue. Assuming regenerative braking?? Good Luck!

[Speedy G]

Thanks! Yeah, I saw those gearboxes, I forgot to list them. Colemanracing.com sells them:

http://www.colemanracing.com/Lightweight-2-speed-Transmission-P6179.aspx

2 x 2 speed gearboxes would be better than 1 gearbox with a differential since I'm using 2 motors anyway, but my problem was finding something that could couple each gearbox to the axles. Also, what drove me away from those gearboxes was the fact that most of them say that they're not meant for hard starts, but rather just to get the car moving. They're also straight cut and require rebuilds often. Then again, each gearbox would only be pushing 170 ft lbs so they should be able to hold up.

Regarding CVTs, they usually use torque converters for initial slip and to ease the shifting. That makes them less desirable due to inefficiency. Also, they're really not a good idea for electric motors. My wife's car has a CVT and when you step on it, it goes all the way up to 4000RPM and stays between 4000RPM and 5000RPM between 30 and over 100mph. It does that to optimize for a gas engine's max torque. My motors have max torque between 0 and 7000RPM so a CVT would actually be counter productive.

As for regen, yeah, I have regen up to 200hp worth. Honestly, I don't know how it'll be to drive a rear wheel drive car with regen entering curve. Some of the Formula E guys talked about it being difficult. The big question is how to bias the rear brakes.

[rtz]

Like what Jack was saying during the show this week in regards to using a standard 5 or 6 speed transmission. Examples: You're going up a steep driveway; put it in first. Driving around town; pick 2nd or 3rd. Out on the highway; put it in 5th or 6th. Essentially single speed when in use; but allows you the choice of the best gear for the job. The Subaru trans will work just fine.

[Bob_n_Cincy]

Like what Jack was saying during the show this week in regards to using a standard 5 or 6 speed transmission. Examples: You're going up a steep driveway; put it in first. Driving around town; pick 2nd or 3rd. Out on the highway; put it in 5th or 6th. Essentially single speed when in use; but allows you the choice of the best gear for the job. The Subaru trans will work just fine.

I built my first EV in 1998. It was AC system tied a 5 speed manual in a minivan. I drove it a lot like you describe above.
That was back in the Lead Acid days and only 50 miles range with at 1300 lbs battery pack.
Bob
37366 37367 37368 37369 37370 37371

[Speedy G]

I agree about the subaru tranny being obviously fine for driving around town, but the build idea is to optimize for acceleration with decent range and top speed, and I like paddle shifters. That's why I considered all the other trannies. Also weight is a big factor in my build because of the batteries, so something lighter could've been advantageous which is why I looked at the powerglide and the 2 gear circle track trannies. The truth is that I wasn't able to find anything better than the subie tranny, but hopefully someone develops something cool soon. I like what these (http://www.drivesystemdesign.com/whatwedo/products/m-sys-transmission/) guys are developing, although I don't agree with in-wheel motors and don't think rare earth motors are a good choice, even if they're slightly more efficient (not in this case though), and slightly lighter than induction motors.

Bob, did everyone think you were crazy back in '86 building an EV? Talk about early adopter...

[Speedy G]

SpeedyG,
Have you laid out your traction pack yet? I'm still in the middle of figuring out the best layout for my build.

Nah, I need to wait for the kit to get here. You gotta remember I'll be trying to reuse as much as I can from the white lightning drivetrain. I have an aluminum structure where the 2 motors are bolted onto, and 2 pulleys that tie the motors together. On the lower pulley, in the back, I have a female 16 spline pinion coupler. I'd like to have one motor over the other if there's enough room, but we'll see when the chassis gets here. After that I need to figure out where to fit between 100 and 120 batteries, that's the hard part.

[Speedy G]

Hey Gary, I got ya. The thing is in this case 300kW is the equivalent of 10C because the estimated current is 1000 A @ 300V. Also about the 100 batteries delivering only 335hp, that's why I'll be trying to fit 120 instead, but honestly, I'm not sure where yet. I don't want 80% of the weight on the rear axle. Also battery to tranny input shaft efficiency is 91% at it's best, but since I have a synchronous belt coupling the motors together, I'll only have high efficiency at low rpm.

[Speedy G]

The topic of BMS or not has been a hot one on several forums for quite some time. Enough years have passed now with enough experience and data to prove that LiFePo4 does not need to be actively balanced. I subscribe to manually balancing, preferably bottom balancing, and not exceeding a charge voltage of 3.6vpc. I actually charge to only 3.45vpc. The capacity above this point is not much and the life is prolonged with this approach. As long as you have a well balanced pack, this approach works well. I have been running this way for years on the older CALB SE cells, with no balance issues. I've also run a booster pack of A123 32157's the same way.
There are some caveats, such as having cells in the same pack exposed to different temps, as well as significant differences in capacities.
It is widely believed that most catastrophic fires are caused by BMS's failing to stop the charging process and overcharging leading to thermal runaway.
Other lithium chemistries seem to require a little more balancing care . . .but I'm not sure i would charge most of them at night in my garage... lol
I think a BMonS (monitoring) is not such a bad idea. . . BManS (managing, meaning top balancing) not so much required. Some folks have coined these systems Battery Murdering Systems... lol

Discharging is ok down to -20C typically for LiFePo4 although performance suffers greatly at colder temps. The real thing to avoid is charging below 0C. This will cause lithium plating and shorten battery life significantly.

cheers! :)

Gary, it sound like you're going to be able to help me out when the time comes... I'm actually thinking of getting the newer CALB cells. I was thinking of doing bottom balancing and monitoring voltages as you stated. The monitoring is more of a neat-o than a real need in my opinion. I just like having all the variables in any given system. In other words, if my cousin's M5 beats me in the 1/4, I want to know what to blame ;-) Also, I'm on the equator, well, 14 degrees North but close enough, and although I live at 10,000 ft of altitude, the temperature here barely ever gets below 40F, but if that's not recommended, the on-board computer will have an environmental temp sensor to shut off the charging.

In terms of charger, all I need is a plug, 220V, 110V, 308V or even 420V. My system has AC Propulsion drives which use the on-board IGBTs as the charger. They patented the idea which is why everyone else needs a charger. I can charge at a rate up to 20kwh. Too bad it's not a Gen II, since I could use the battery pack as my home's UPS (probably for a couple of days).

Regarding cooling anything, it'll all be water cooled if need be, although the LiPo cells don't get that warm, usually. Temp sensors in the battery packs sound like a good idea.

[Gary Livingston]

Hey Gary, I got ya. The thing is in this case 300kWh is the equivalent of 10C because the estimated current is 1000 A @ 300V. Also about the 100 batteries delivering only 335hp, that's why I'll be trying to fit 120 instead, but honestly, I'm not sure where yet. I don't want 80% of the weight on the rear axle. Also battery to tranny input shaft efficiency is 91% at it's best, but since I have a synchronous belt coupling the motors together, I'll only have high efficiency at low rpm.

You mean 300kW right? Not kWh.
Have you looked at fitting 120 pieces of 100 Ah cells in that car with two motors/controllers? I don't want to sound pessimistic and I haven't laid that out but. . . wholly crap I would eat my hat if you could fit those all in there.

You mentioned wanting to build a super car. CA cells are awesome, but they are not "super car-ish" cells. If you want a super car cell, go for the A123 AHR18700F1 cells. . . . but ur gonna need very deep pockets. lol

Seriously though, what are your range and performance goals?

[Speedy G]

Yeah, the space issue... If we start out with Eric's 50, maybe add another 9-12 since my motors are shorter, and another 12 can probably fit in the center channel, even if we have to remodel it a bit. I'll probably have to fit another 18 in the back on top of the other ones and the rest are a bit ???. We'll see how everything fits once I get the chassis and I'm able to digitize it into solid works or something similar. However, CALB now has the CAM cells that could be useful if they make 120Ah cells. Currently only 70Ah cells are out. We'll see. If I can't get them to fit between the axles then they'll have to go in front of the front ones (most probably). More compact cells would definitely be usefull, but I've been thinking of staying away from other chemistries due to combustability.

Regarding the controllers... yeah, especially the AC Propulsion ones are just huge. They'll have to go on top somehow. For the first stage of the project, I only need to fit 1 since the other one is broken. To get both motors working I'll redesign the power stage with modern stuff. That should save a lot of space, especially if I use water cooling.

The range isn't all that important. I'm more interested in performance in the 1/4 and daily driving short distances (<50 miles), and keeping a reasonable budget (not more than my beamer). Beamers cost 2x as much here btw.

[ehansen007]

Hey speedy. I can say that there is a bunch of room left for me to add batteries including in front of the nose but running them down the middle might be tough but doable. I found that dropping the shifter made it harder to fit cables along with the small harness for the controllers. One thing to rember for sure is to keep those batteries accessible for balancing! Are you going to run a BMS? Also, if I had to do it over, or if this second tranny goes like the first one, I would go with STi tranny for strength. 1st gear is almost useless so with the torque you'll be making you'll still have a nice 5sp. I'll see what can do about the solid works file.

[Gary Livingston]

Hey speedy. I can say that there is a bunch of room left for me to add batteries including in front of the nose but running them down the middle might be tough but doable. I found that dropping the shifter made it harder to fit cables along with the small harness for the controllers. One thing to rember for sure is to keep those batteries accessible for balancing! Are you going to run a BMS? Also, if I had to do it over, or if this second tranny goes like the first one, I would go with STi tranny for strength. 1st gear is almost useless so with the torque you'll be making you'll still have a nice 5sp. I'll see what can do about the solid works file.

Hey Eric. How do you like the car now that you have had if for a while? Have you put many miles on it? Drive it regularly?
The solid works file would be awesome. I heard EVWest modeled it. It's probably worth something to them though. I still may do that. . . but for one car, not sure it's worth it. . . maybe if I was building more.. . Did you look at the EVIC display for Curtis?

[ehansen007]

The car is awesome. Just plug it in and go. I'd always like more range but that's just a function of cost for me. I've got about 400 miles on it and the only thing that bugs me is the rubbing on the front fenders (I'm running 18's with spacers so it's right at the edge) and how low the car is in general. I love the way it looks as it sits but it's a bit scary going in and out of driveways with the splitter on. And, (and this is something that everyone should know) this car is so low I can't even get it on a flatbed trailer to have it towed home. I'll carry some spacers for the springs with me and hope that if I do need a tow, that he'll have a low profile jack so I can at least get the car high enough to get the spacers in. :) I hadn't looked at the EVIC as it was not available but it looks pretty good. I like having all that data in one place. The problem is that they don't list whether or not you can convert it to Fahrenheit for the motor and controller temps. The pro would be the way to go though since it's got MPH too so you can make it the instrument cluster. As long as you could design the interface to fit within the subie cutout it would be awesome. Square just doesn't look OEM. Finally someone has done it though which is great.

[Speedy G]

Hey Eric, no worries about the solidworks file. It's EV West intellectual property and I respect that. I talked to them, but they didn't seem to really get into the project. They gave me some recommendations for which I'm grateful, but they're more focused on lower cost systems like yours where you have to put together a bunch of systems to be able to have a complete system. The truth is, the only parts I could buy from them are the batteries, and there's better prices out there, not by much, but still.

AC propulsion motors I think start at 25k for each with the controller, but I can hook up a regular fuel gauge, a regular odometer (to 13000 rpm though), and even a regular speedometer (2.5V/12,000rpm). All I have to do is hook up the motor to the controller, the batteries, the gauges, and the gas pedal, and I'll be ready to roll, charge, etc. I was lucky to get a second hand ACP system so the cost was much lower, but still a little higher than yours. The second motor/controller, and the second 200hp will take more time. Also, the ACP advantage is lower weight (50kg/110 lbs for the motor) due to a higher rpm design. Higher RPM 400 Hz designs need less back-iron.

In terms of the chassis schematic, I'm sure there's been some changes to the chassis as well. I do plan on doing some structural simulations since I'll be using quite a bit more weight, which is why I prefer redoing the digitizing. It might be useful for others since there's the question of the brace bars in front of the seats, etc, so I'll probably post it if I get it done properly. I'm not sure how FFR would feel about me posting it though. Maybe I'll distribute it on a case by case basis.

Btw, since I'm thinking of only running in second gear initially I won't be needing a shifter (well, reverse is a switch, and I will have a start button). Eventually, I'll be getting the mastershift system so my shifting cables can be really short and shifter motor can be right next to the tranny, behind the batteries. The only issue, then would be the e-brake cables. There is an e-e-brake conversion where it becomes a switch, but I'm thinking it might be more fun to have a mechanical one. If I'm going to have a heavy butt, maybe I can use it to drift a bit? Also, there's the issue of how to route wiring. I'll be using the isis stuff, so few wires will be needed. I'm thinking of hanging them out the side like the water ducts that go to the front. Btw, one reason for having the batteries in the tunnel is that fewer long power cables can be used. Only a return cable from the front to the back would be needed (battery ground sounds like a good idea).

In terms of BMS, I love the display of the LIGOO system. I'd love to have an automatic balancing system, but I'm not paying $3500 for battery monitoring and questionable balancing. I'm not sure what I'll do, but what I'm thinking is monitoring the voltage of each group of 9-12 batteries. 9-12 seem to be the most convenient grouping when looking at Eric's build. The software is easy enough, It's just reading from some a/d converters and compare them to historical and common sense numbers. The issue might be the voltage conditioning circuits (I'll need isolated differential reading and conversion of 28.8V -> 5v or 38.8V ->5v). I'll probably use some of the design of the ligoo displays on the display computer.

[Speedy G]

At this point I'm realizing this project is getting so big that I'm going to split it into sub-projects. That way I can focus on just what's to be done for the current stage and this thread can be more focused. Stage I is the stage after which I register the car, and the following are what I see as landmarks or stages:

1) Stage I: The most basic system needed to get registered. Drivetrain consists of 1 ACP controller, 1 200hp motor, 1x 5mt tranny stuck in 2nd gear, no clutch (direct coupling), 100 batteries, basic instruments (gas gauge, speedometer, odometer, basic gear control (N, D, R, but not sure how yet). Obviously this includes a finished 818 in every other aspect. Wiring will be Isis, and at this point, no bells and whistles. The toughest problem at this stage is the coupling of the electric motor to the 5mt tranny. It's going to have to be custom made. Fitting the batteries will be another issue.

2) Stage II: Although some of the work will be done in parallel to stage I, this stage includes a display computer with a touchscreen mounted on the center column. There's tons of data available, so the inital display computer will just show data (rpm, speed, motor temp, controller temp, battery voltages, battery current, battery capacity left, etc.). The display computer will also include the entertainment system. The cubietruck computer will be hooked up to a DAC that drives a power amp directly. Media options will just be bluetooth, local hard drive and USB drive. I'll post everything regarding this project in the body & interior forum.

3) Stage III: This stage is about getting the second 200hp motor online. This calls for redesigning the power stage of the ACP controller. Hopefully the ACP logic circuits can be used from both PEUs and be hooked up to a much smaller footprint power stage. If I have time I'll start doing the power stage design in parallel since all I need is my laptop.

4) Stage IV: This stage is about control systems. Speed dependent power assisted steering, brake vacuum asist, customizable traction control, different drive by wire programs and regen. And the mother of all control systems, the shifting control system. I'm thinking I'll need a second onboard computer for this.

... Hopefully I have more than 2 years worth of work ahead of me. I'm more of a grease monkey than a pilot, so it should be fun.

[Bob_n_Cincy]

He speedy,
Now take stage one and split it into a 15 to 20 weekend task.
I thought the ev part would take most of the time and the kit would be erector set. I WAS WRONG.

I don't know this guy(Steve Cornett), but he made and adapter and flywheel for a Subaru MT5. If you contact him, let me know what you get.

This is one of the better conversions I've seen.

Looks like he's get 40 mile range with a 16 kWh pack. The lite 818 should get 20% more.

Here is a link to his motor adaptor. http://www.electricsubaru.com/adapter.html
Bob

http://www.electricsubaru.com/


http://www.evalbum.com/4229





http://thefactoryfiveforum.com/attachment.php?attachmentid=37598&d=1421129278

[Speedy G]

VERY helpful, thanks! Erector set... yeah, I've been reading. If it were easy would we be doing it? Actually the EV part for my stage I just looks time consuming. The rest looks like it needs some real skills.

[ehansen007]

EV West makes the adapter plate andd coupler as well since they did model it for my car. They are just busy as hell over there right now. I had one on order from Rebirth however the integrated coupler/bearing was having wear issues with the key on the shaft of the motor. At least on the HPEV AC shaft anyway. I remember talking to Steve Cornett as well. I was talking to EVERYONE at the time as it was hard to find info and make the right choices! Again, be wary of the stock WRX transmission even in 2nd gear only. If the tires are hooked up the stress is going to go straight to that tranny and I'm also not sure how long those bearings will last going over 7K RPM constantly. Might want to look at a rear diff or purpose built gear box for single speed.

[Speedy G]

Yeah, the thing is I'm running without a flywheel and without a clutch. Since I inherited the white lightning rig, the tranny will hook onto a converter that couples directly to a spline socket. For this reason, adding a flywheel would be more difficult. So it was either do without the flywheel and clutch, or totally redo the rig that couples the two motors, so I opted for the easy way out, even if it's not the most efficient. All I have to have custom made is the coupling between the spline socket and the tranny splines, with 1 additional issue, the coupling should be insulated. Also, aligning the tranny with the spline socket is very difficult. Just a little off and your bearings are kaput. I might use some kind of forgiving coupling, we'll see. I'm still not sure how much room I have.

Btw if it's the bearings that die from going over 8kRPM then I'll be happy. Those I can replace with ceramic bearings. I'm more worried about the gears themselves. The higher the RPM the higher the stress on the gear teeth, and I don't think the relationship is linear... I figure I won't be driving much over 100 kph often (that's 7kRPM speed). At least not initially. Once I get it shifting, there's really not much advantage shifting at 10,000 RPM (optimum shift point) vs 6000 RPM except that the motors might heat up more shifting at lower RPM. I've been wondering if oil cooling would benefit the durability of the tranny. It would have to be a DIY kit though.

[John Rubicon]

Hi Speedy G,

I just read this thread and may I say, you are an intrepid builder. I've used the ACP drive and would be delighted if someone replaces the air-cooled IGBTs with modern silicon cooled by water. Keep us posted on that aspect, please.

On your discussion regarding autoshifting, I have some experiences to share. Getting custom firmware from the Mastershift guys is, in my experience, not worth the wait. Been there, done that. The device uses a cable pull, but the potentiometer-encoders are at the motor end of the cable, so cable stretch makes for less than precise shifting. This may not manifest as a problem in transmissions with loose gates without lockouts. We ended up just driving the Mastershift hardware with our own H-bridge and a separate controller. Worked, but not as reliably as we wanted. I'm going to look at using a servo-hydraulic x-y shifter that VW made. I have it and it's OEM quality.

Another potential problem is that the ACP motor has a speed encoder, not a position resolver, so its "RPM" output from the controller is a low precision variable that gives a poor state estimator for matching RPM targets during shifting.

I'm using PMAC motors and also plan an autoshifting setup.

As for 12000RPM motors and transmission life, I have to be honest and say that my experience is that the bearings go south quickly above 8-9000RPM. My PMACs are 6-7000 RPM and 530 ft-lbs.

I look forward to your thread and in collaborating with you.

JR

[John Rubicon]

Speedy G,

one other thing to consider is that the ACP motor output shaft should be galvanically isolated from your transmission to prevent the large induced currents in the rotor from driving current through the rotor bearings and causing them to gradually fail. Heck it may even throw a ground fault if you don't. The belt drive provided this function in the White Lightening prototype. ACP used a Honda(?) clutch hub mounted to a phenolic disk to provide that isolation in Gen 1.

Oh, and if you do replace the controller phase boards, please don't throw them away! I and others need spares ;-)

JR

[John Rubicon]

Sorry, double post...

[Speedy G]

Awesome to hear someone' s further along my madness. Good info on the bearings and the mastershift stuff. At least now I'm not flying as blind. Yeah, I figured I'd have to drive the mastershift with my own h-bridge. Let me know how that vw x-y shifter works. Is it easily available or is it a 1-off? It actually sound like a cheaper option? I still like mastershift's paddle and bump shifters though.

Hey John, do you have any info on the igbt outputs? I'm needing switching frequency and maybe how much they dampened the switching. An o-scope image would be great with scale info. I can' t start working on that since I don't yet have the voltage to turn the suckers on. I already have the IGBTs, the conditioning circuits and the cooling plate. All I need is the snubber caps and I can drive one of the motors with a microcontroller. For that I need the frequency and a sample voltage/time graph.

[John Rubicon]

The x-y from VW was used in a couple of european models over a decade ago. So OEM, but rare. I could make it a paddle shifter with the right code and a paddle shifter hardware set that mounts to our GTMs.

Typical switching frequencies are 4-12kHz. Higher than that and the IGBTs get lossy. I have some experience with SeimKron IGBTs - great products. What IGBTs are you using?

Switching, of course is modulated to try to follow the back-EMF of the motor At higher speeds, the more irregular the back-EMF, the high frequency modulation one has to do to control the motor efficiently. At some point you run out of frequency headroom trying to match the ripples in the back-EMF.

The above should be tempered by the fact that I have experienced only PMAC control and not induction motor control. The PMACs can have a "lumpy" V vs. time graph and so switching speed limits effect how well you can "follow" such a curve. Induction motor back-emf may be much "smoother" and therefore easier to control.

In either case, a gate driver will help you protect your expensive IGBTs as they have safety timing features built in. noise, stray capacitance and other effects can alter the signal coming from your micro-controller before it gets to the IGBT gate terminals. So, typically, a gate driver circuit is located very close or on top of the IGBTs. IF your not careful, however briefly, you may inadvertantly command both the upper and lower IGBT on a leg to be "on" at the same time. That's a direct short and a very expensive fireball. The gate driver circuit takes the signals from your microcontroller and then triggers it's own moderately powerful transistors to trigger the IGBTs.

[Gary Livingston]

Hey John, do you have a build thread? What brand/model motors/controllers are you using?

Cheers

[John Rubicon]

Hi Gary,

I am using motors that were used in the Fiskar Karma sports car. It is very hard to get these motors since Fiskar has been resurrected by the Chinese company that bought them, but I have connections. My company matched them to our own inverters for use in heavy electric trucks. They've also been matched to a chinese inverter and a swiss inverter, but these last two are really not rugged enough for trucks. Or supercars ;-)

I haven't started a build thread yet. But I do have one that could become one called "So I just bought a partially complete GTM...now what?" in the Intro forum, and one at the "other" site under the same "handle". It'll be a couple of weeks before motors and batteries arrive.

JR

[Speedy G]

That's why you're talking about resolvers... You deal more with PMACs where startup torque is more difficult. There's really little reason to use a resolver in an induction motor since flux orientation is not dependent on the position of the rotor. Induction controls usually depend more on just 2 phase currents, voltage, drive frequency (an encoder is also required for DTC).

I'm surprised to hear the encoder wasn't accurate enough for shifting. I was doubting the accuracy of the subie tranny encoder since it's only 2 bit (4 pulses per rev), but I'm thinking of using a hardware counter scheme at high frequency so I can get more precision. I'll have to see if I can do the same for the motor encoder if we have the same issue.

I'm using Powerex IGBTs. I looked at the Semix stuff (specifically the SEMiX603GB12Vs IGBT). They seem nice, fast(er) and cheap! The reason I chose the Powerex (CM600DX-24S1 (http://www.pwrx.com/Product/CM600DX-24S1)) is because they also sell the gate driver circuit (VLA536-01R (http://www.pwrx.com/Product/VLA536-01R)), which is what I called "conditioning circuit" earlier. I also found the cooling plate easily on the web (cp-1001-xp (http://www.microcooling.com/cold-plate-products/standard-cold-plate/cp-1001-xp-detail) easily good for 3.3kW of dissipation). That makes for a really compact power stage for the power it can handle. Since I'm going for a simple solution, I'm not sure the replacement power stage will have all the bells and whistles that the original had (regen, charge w/ same IGBTs, etc). The reason for that is that the snubber circuit may be in the way of some of those, we'll see. The advantage of what I'm doing is that if I can find the pwm output at the microprocessor of the original drive, I can pretty much connect it straight to (but isolated) the new power stage without too much trouble. Also, it was a package deal so I might as well use everything I can.

I may have a board or two left over from the original drive (gate drivers probably for sure) after I replace the one with the powerex. Also I think 1 of the IGBTs is still good as well as capacitors (but they ARE 17 years old). I'll let you know what's left for reuse after I'm done.

I'm curious as to what switching frequencies they used, since 17 years ago (or even 20 since mine was number 2048) IGBT losses must've been much higher and since that's related to switching speed, I'm pretty sure they switched at lower freqs than current controllers. That, without taking into account DSP processing speeds available back then. Back then it was more art and faith than the lego style design that is possible today. You are inline with what I was thinking in terms of frequency, but there's nothing like a real life waveform to validate assumptions. I just need the max switching speed for the dimensioning of the stubber caps, so it can wait. I still have to analyze how they did the regen circuit, etc to see how much I need to redesign.

As far as the electrical isolation of the rotors, there's little room, so I'm thinking of using ceramic bearings for the coupling pulleys. The documentation shows me some phenolic disc coupling with the tranny, but since my talent isn't in high speed rotating assemblies, the less I do the better. The truth is that although the rig could probably take the 12,000 RPM for a bit, shfiting earlier doesn't hurt acceleration, 8-9k is fine. It's not like I get more torque at a higher rpm. The coupling pulley really drops efficiency above 5kRPM anyway.

BTW, I'm hearing sooo much stuff being done in electric trucks. It sounds like a lot more than regular EVs. I've spoken to a few that are doing truck trannies for electric motors as well. What's going on? Are trucks in the next decade all going to be EVs?

[John Rubicon]

Speedy,

I apologize for writing to you in such overly simplistic language about a subject that you clearly know well. Electrical Engineer? Power systems is rarely taught in Universities anymore, so most EEs are not well informed on these subjects.

I've met almost all the ACP Caltech brain trust, great men, Al C even took me for a spin in the original TZero. That was some real hocus pocus back then - you've seen inside the product... I guess the 7 Amp discretes were just good enough and cheap enough to make the product work. They took the same approach when they built the proto-pack that became the Tesla Roadster pack. Lots of small cells.

Those PowerEX half-bridges are rugged product. Little lossier as I recall. You know the Semikron folks make awesome 6-packs with integrated driver and heat sink, right? Assembled, tested, bulletproof - more expensive...See http://www.sindopower.com/Products-and-Shop/Product-Groups/IPM-SKiiP/SKiiP/voltVal1200/currVal6/S33/?cur=1

I should get my batteries in the next 2 weeks, and among other things, I want to resurrect my ACP unit and spin it up. I'll capture the switching frquencies for you under small load if you can write me a procedure showing me where, and how in the circuit. Would this be on the motor leads? It might be 2-3 months though. OBTW, wouldn't the phase board cap set teach you what the snubber should look like? Or is that more dependent on the IGBTs than the motor inductance? I had ACP replace all the stock 400VAC electrolytics with 440VAC versions. Running close to 400V battery voltage in the heat caused a bunch of their inverters to blow up. This was the fix.

Electric trucks? Yeah, check out www.transpowerusa.com. Batteries are just good enough to make the proposition feasible. These are the best available, IMHO. You be the judge. Full disclosure: I'm a founder.

So you really live in Columbia, the country known for such beautiful women? Or is it Columbia , South Carolina. I've been looking for a reason to visit Columbia, maybe we can have a "technical" meeting in person sometime and write that trip off :-)

[Speedy G]

Yep full gEEk. I actually worked on an earlier project as a coop (intern) engineer. We developed the craziest highest budget (probably) hybrid engine ever, the patriot project. That was at SatCon Technology back in '93. The contractor was Chrysler and the engine was a dual turbo-alternator (essentially two mini jet engines each coupled by shafts to alternators), flywheel storage, a water cooled induction motor and all the electronics to control all that, including the IGBTs. I think they applied for patents ranging from igbt designs, to turboalternator designs, to control design. The power electronics managed something like 3.5MW and only weighed 140lbs. The motor controller was also vector controlled (or FOC), so the thing was really on the edge of tech for the time. Everything was really high speed. The lowest speed thing in the engine was the 4 pole induction motor running at 24,000 RPM (750hp). Up from that we had the low speed turboalternator @ 50,000 rpm, the flywheel storage weighed 147 lbs and ran at 60,000 rpm, and finally the high speed turbo alternator ran at 100,000 RPM. All this fit in a racecar that was going to race at the then new American Le Mans series. There's a lot of lies about that project on the net, but the truth is Satcon did build it with around 30 engineers (mostly MIT), the budget was $35 million spent not $5 million as most web sites say, and I think 2 full engines were delivered (5 were the target). There's also a misconception on the net, they say the engine was 500hp, but they somehow didn't count the flywheel stored energy. The turboalternators were able to supply 500hp constantly, but the flywheel could supply another 250hp coming out of a turn, so effectively it was a 750 peak hp engine, with a nominal 500hp. Starting torque was 525ft lbs, with a flat 350ft lbs to 12,000 RPM.

The project was scrapped because the explosion of the flywheel was not contained by the container. Theory, and practice at SatCon said that carbon fiber flywheels turn into a kind of foam when they disintegrate at high rpm. For some reason this flywheel didn't disintegrate correctly. My though is that it was just larger than what we usually dealt with (notice I said larger, not higher speed).

These days I'm more on the software side of things, and I haven't touched high voltage in decades, but the reason for getting my feet back into electric motors is that I remember that project as being crazy awesome. It's really sad that a company that was able to do all that in '93-'95 still hasn't found its niche. Really brilliant and crazy cool bunch. Kers... yeah, we did that back in '94...

The thing about the ACP controller caps is that cap technology has also advanced a lot in the last decade. You just told me they used electrolytics, which is something I wouldn't use today since now we have high current film capacitors. That means they didn't have some circuit topologies available to them back when the drives were designed. Now you can just put a snubber cap directly on the IGBT, simplify the circuit, and improve efficiency. Back then they were probably forced to use a dissipative resistor in there somewhere, which just turned precious electricity into heat.

In any case. Cool to hear about your startup. It makes all the sense in the world, here even more. We probably have more hydro power than any other country, so going electric here is truly green. It is Colombia, South America. Booming place btw, and yes the current Ms Universe is Colombian, and Obama's security detail hooked up and got caught when they came down.

Btw on Linked-in, check out the Hybrid, Electric, PEV, and PHEV Engineering Professional Group Hybrid, Electric, PEV, and PHEV Engineering Professional Group. It's really relavant to what you're doing.

[Bob_n_Cincy]

Hi Guys, This is kids stuff, JK
I could not help myself. On my build thread you have probably seen my son Michael Working on and driving the 818.
Here is Michael doing final assembly on an 80KW flux vector AC inverter. It is headed for delivery truck application in Mexico City. I think this was in 1999.
38379
He's a little bigger now.
38380

I had 3 or 4 of the controller is these races. ACP was in Ohio State and Oklahoma.

http://youtu.be/F6qjJWFRrlI

[Speedy G]

Well, your drive looks waaay smaller than the ACP Gen1.

[Bob_n_Cincy]

Well, your drive looks waaay smaller than the ACP Gen1.
I had a liquid cooled version with 800 amp IGBT that I rated at a peak of 160kw used in 22 passenger shuttle buses. Size 12x24x7 I will probably use one of these in my 818e. I also might use a brand new controller out of an EV1. I should donate it to a museum.
38386

[Speedy G]

Nice Bob! Those look really cool btw. What did you do about the control algorithm? Did you program it all yourself? What about motor parameters and modelling? I love the name "Fluxdrive".

When do you think you'll start you e-build?

[Speedy G]

Hey John, I just looked at your website, NICE! You wouldn't happen to know Frank Falcone? I had an interesting discussion with him in the forum I told you about, so in fact I may have been talking to people in the same company about ev trucks!

An interesting idea popped up in that discussion. The prius uses something similar. The idea is to use a single planetary gearset as a transmision for high efficiency. If you could just use clutches to couple the wheels to either the ring gear OR the planet gears OR the sun gear, you could have a 3 gear tranny as simple and as efficient as can be. In fact that's how the powerglide tranny works, only with a bunch more stuff for autoshift, and the torque converter. If I were an ME I'd be all over that. I'd also do a dual planetary version to replace the differential and use 2 motors.

[John Rubicon]

Hi Bob,

Impressive! I like how its a family passion. You and I and Speedy seem to have been bitten by the electric performance bug. That feeling is so powerfully different from infernal combustion that it lasts for decades.

Are you selling inverter drives? If so, have you matched to an IPM machine?

JR

[John Rubicon]

Hey John, I just looked at your website, NICE! You wouldn't happen to know Frank Falcone? I had an interesting discussion with him in the forum I told you about, so in fact I may have been talking to people in the same company about ev trucks!

An interesting idea popped up in that discussion. The prius uses something similar. The idea is to use a single planetary gearset as a transmision for high efficiency. If you could just use clutches to couple the wheels to either the ring gear OR the planet gears OR the sun gear, you could have a 3 gear tranny as simple and as efficient as can be. In fact that's how the powerglide tranny works, only with a bunch more stuff for autoshift, and the torque converter. If I were an ME I'd be all over that. I'd also do a dual planetary version to replace the differential and use 2 motors.

Do I know Frank Falcone? Yeah. He was my MSME student while I was a professor, and I liked his skills so much he was my first hire. I'm looking at him in the flesh right now....small world, eh?

The idea you guys discussed is one that came out of my lab a decade ago when we were working with racing transmission builder Lenco. Their stuff is all planetary. I think this is in essence what Wrightspeed does now. Planetary units are lossier than spurs gears when not in 1:1. And the Lenco unit of the day was not meant for more than a dozen trips down the track between rebuilds. I passed on spending time on that due to the investment required and the absence of a performance market at the time. I know of a Powershift product that converts all the auto functions to manual for racing use, but I still wouldn't want to put 1050 ft-lbs through it.

JR

[Bob_n_Cincy]

Nice Bob! Those look really cool btw. What did you do about the control algorithm? Did you program it all yourself? What about motor parameters and modelling? I love the name "Fluxdrive".
When do you think you'll start you e-build?

The deep FOC code was already done, I did write the all the frontend code. I think I still own Fluxdrives, fluxvector, and electricmotorsports web domains.



Hi Bob,

Impressive! I like how its a family passion. You and I and Speedy seem to have been bitten by the electric performance bug. That feeling is so powerfully different from infernal combustion that it lasts for decades.
Are you selling inverter drives? If so, have you matched to an IPM machine?
JR

I been working on motor controller for the last 35 years. I'm having a blast working on my turbo 818.

I sold off my business in 08 and now work in the ev industry.
Yes, A lot of stuff I've done in the last couple of years has been with IPM motors.

Talk about family. This is after we won the 2010 TTXGP national championship. My daughter, son and me on the right. If you guys know the name Jeff Major from the EVDL. He is a close friend in the back row.
38393
Bob

[Gary Livingston]

Hey John,
Very kewl. Thats some serious power there. Should be a nice package by the sounds of it. What battery are you using? The Fiskar A123 pack perhaps?

[rtz]

Maybe EnerDel?

http://www.diyelectriccar.com/forums/showthread.php/enerdel-battery-modules-86089.html

[Gary Livingston]

Maybe EnerDel?

http://www.diyelectriccar.com/forums/showthread.php/enerdel-battery-modules-86089.html

This is Jeff Major, Bob's friend. I learned a lot from him. He helped me to design/build a 13" series wound motor from parts used from a couple other motors. I think I have some 2400+ posts on that forum also. :) The enerdels are used on Richard Hatfields Lightning bikes. (the team Bob and Jeff are on).
I was referring to to John Rubicons' post where he said his motors and battery were coming. His motors being from the Fiskar, are the Jing-Jin ones I think and the battery pack from the Fiskar cars was A123. So.... was wondering if he is getting one of the batteries from the Fiskar builds also. Nice 20KWh pack.

[John Rubicon]

This is Jeff Major, Bob's friend. I learned a lot from him. He helped me to design/build a 13" series wound motor from parts used from a couple other motors. I think I have some 2400+ posts on that forum also. :) The enerdels are used on Richard Hatfields Lightning bikes. (the team Bob and Jeff are on).
I was referring to to John Rubicons' post where he said his motors and battery were coming. His motors being from the Fiskar, are the Jing-Jin ones I think and the battery pack from the Fiskar cars was A123. So.... was wondering if he is getting one of the batteries from the Fiskar builds also. Nice 20KWh pack.

I have some experience with Enerdel's packs. Overall good tech, No, I'm using an excess of Nissan Leaf modules. Alligator versions. 6C on their best day, but if you know you're going to parallelize them, then that is not an impediment. A123 i a great drag racer choice, but I think the Leaf module is better when energy is also a consideration. I'm shooting for 140 miles range - which by the time I finish the vehicle, may be child's play for new tech cells in development now. Still hard to argue with high-volume OEM cells, If I can fit 1500lbs in the vehicle :-0

JR.

[Gary Livingston]

I have some experience with Enerdel's packs. Overall good tech, No, I'm using an excess of Nissan Leaf modules. Alligator versions. 6C on their best day, but if you know you're going to parallelize them, then that is not an impediment. A123 i a great drag racer choice, but I think the Leaf module is better when energy is also a consideration. I'm shooting for 140 miles range - which by the time I finish the vehicle, may be child's play for new tech cells in development now. Still hard to argue with high-volume OEM cells, If I can fit 1500lbs in the vehicle :-0

JR.

Oh ok kewl. These packs are starting to come available from wrecks also. The NMC (lithium nickel manganese cobalt oxide) are a better chemistry than many for energy density. The trick with these cells it seems, is to limit the the charge voltage and high temperatures if you want to preserve cycle life. Seems Nissan may not have fully captured the effect of one or both of these influences since many owners in. California have experienced a 25% loss of capacity over 1 - 2 years. If you are picking up a used pack, might be better to source one from the more northern states. ;)

[John Rubicon]

Gary,

you're right on capacity loss. I have the newer "Alligator" gen cells that have better cooling. Also, the 2015 pack I received is pristine ;-) Charge voltage is a little more under my control than in the Leaf, also. I'd be interested in a life vs.SOC at max charge kind of graph if it were in the public domain. I expect that the last 5-10% charge does most of the life-reducing damage.

[Gary Livingston]

Gary,

you're right on capacity loss. I have the newer "Alligator" gen cells that have better cooling. Also, the 2015 pack I received is pristine ;-) Charge voltage is a little more under my control than in the Leaf, also. I'd be interested in a life vs.SOC at max charge kind of graph if it were in the public domain. I expect that the last 5-10% charge does most of the life-reducing damage.

Oh, that's good. I've heard them termed "lizard" cells and have some more secret sauce added to preserve high temp service. Far as I know, 4.1 volts is the magic number. Terminate the CV phase of charge below 4.1 and it should make the difference. Did you get one pack? what's the plan for configuration/voltage and what do you suppose you can get out of them peak?

Cheers!

[Speedy G]

Ok, guys since this turned into a battery discussion, you guys got me wondering about what I should do. I need ~1000 amps for drag racing and >120 mile range would be cool. Motors were rated at 164kW and 165kW @ 350V. I was originally thinking of getting just 120 100Ah CALB cells and hope for the best. Now you guys got me wondering if I should go with something like 120 70Ah CALB cells and 30Ah of A123 cells or Enerdel cells.

Gary you talked about the A123 cell pack as a sprinter pack and CALB as a range pack. Is there a ratio of CALB Ah vs A123 that you'd see as ideal? Is there a way to calculate or is it just looking at graphs and guestimating? What would that ratio be for Enerdel? Let's say the budget is 20k for the battery pack.

[John Rubicon]

Oh, that's good. I've heard them termed "lizard" cells and have some more secret sauce added to preserve high temp service. Far as I know, 4.1 volts is the magic number. Terminate the CV phase of charge below 4.1 and it should make the difference. Did you get one pack? what's the plan for configuration/voltage and what do you suppose you can get out of them peak?

Cheers!

Gary, you're right, it's Lizard. Though Alligator sounds way cooler ;-) I have strong rumors that they really don't like more than 375A discharge (not even enough for 1 motor at peak), so I am planning around that for peak power. If you know of data that says they can deliver more amperage, reliably, please do share.

Just one pack to start, to get it proofed for function. I may just have to go higher than 450V to get what I want from the system.

JR.

[John Rubicon]

Ok, guys since this turned into a battery discussion, you guys got me wondering about what I should do. I need ~1000 amps for drag racing and >120 mile range would be cool. Motors were rated at 164kW and 165kW @ 350V. I was originally thinking of getting just 120 100Ah CALB cells and hope for the best. Now you guys got me wondering if I should go with something like 120 70Ah CALB cells and 30Ah of A123 cells or Enerdel cells.

Gary you talked about the A123 cell pack as a sprinter pack and CALB as a range pack. Is there a ratio of CALB Ah vs A123 that you'd see as ideal? Is there a way to calculate or is it just looking at graphs and guestimating? What would that ratio be for Enerdel? Let's say the budget is 20k for the battery pack.

Hi Speedy,

I wouldn't push the small Calb's that hard. That's 10C for the 100Ah units. Calb sells some metal jacketed cells that can go above 6C and likely 10C for short bursts without too much drama. I think they are called CAM-series cells. More $, but they have a fighting chance because they can cool.

On the subject of ACP power, you know that the Gen 1 peak power might last 15-20 seconds, right? That was my experience, at least. Then the hardware must cool for quite a while before it can make another burst. Derate I estimate was to half of peak power or less on a warm day. This is one reason I went with the liquid-cooled IPMs I have coming. They derate to about 75% of peak power, and that takes minutes to happen, not seconds.

If you have $20k to spend, look into whether the folks at Plasmaboy Racing http://www.plasmaboyracing.com/whitezombie.php will build you a pack from the Dow-Kokam's they were using. They were good at this electric drag business ;-)

IF you really want 120 miles AND drag racing capability, then vehicle weight, volume and balance start to be a challenge, as the pack gets larger. That's about what I'm looking to build. So we are in a similar boat. I thought the 165kW ACP drives flowed 550A each, but not sure if that was DC or phase current. My IPMs require about 450A DC each.

JR

[Gary Livingston]

Hey Speedy. Sorry for hijacking ur thread I guess it's all a common pursuit. My initial thoughts are similar to John's on most points. (One point there is that the CAM series cells are the same chemistry as the CA's except for the one CAM model CAM 25P - power cells that haven't quite hit prime time yet)
Personally, I like to back into the battery selection from the controller and motor capability. You say your motors will do 330 kW peak. So if you want to max them out, and you can feed them 500 amps each, you will need to maintain 330 sag volts at 1000 amps. Now what upper voltage will your controllers take? If it's 425 for example, and you want to use LiFePo chemistry, you must determine number of cells based on charge voltage. If you charge to 3.65vpc, you can only use 116 units. Voltage settled after charge will be about 3.35x116 or 388 best case. It will be lower soon as u draw from it. Getting a battery to sag only 50 volts at 1000 amps is a lofty goal.
I don't know if these numbers represent your case, but it gives you the method to determine.
This is what leads to the selection of higher c rate cells as they tend to sag less as well as drag racers looking for light weight packs that will enable them to race 1/4 mile not 120 miles. Clarify some of those points and we can get to the next step.

[Speedy G]

I figured you guys know so much about batteries that leaving some of that info on the board would be good for the community. It's not a hijack at all.

Yeah, I know the ACPs Gen I's are cheetahs, not marathoners. That's also why I'm looking at improving cooling as well, but at first look, the motors look pretty difficult to water-cool. I know mine are modified, but I don't know how they were modified to be able to handle high power longer (2x Bonneville @250mph, 90 s for each run). I know the insulation is still good so Ed didn't cook them. There is one trick, however. If you run them in the upper RPM range, less current will flow through the motors, and they'll run cooler. Also peak efficiency is above 6000rpm and below 120kW (lower than 100kW at higher rpm).

Max voltage in the controller is 420V with original specs so let's assume 110 cells initially, 70Ah pack CALB only (initially for a single motor @500A max or 7C. The upgrade to the second motor would also include a sprinter battery pack. The sprinter pack would probably need to supply at least the other 500A, while only having 30Ah. That would mean running the sprinter pack @ close to 17C. The problem is how to determine the sag of the CALB pack vs the sag of the A123/Enerdel pack to determine how many cells in parallel I'd have to run in the sprinter pack. Is there a graph/equation out there with 5C, 10C, 20C, 30C sag info for those cells?

[John Rubicon]

Speedy, do you intend to keep the two packs separate or to Siamese them together cell by cell to be able to use just one BMS? I know of one build in the siamese design, but it's a cabling and packaging non-starter for me.

In my experience, the cell info you're looking for isn't released by manufacturers because it's outside the recommended operating envelope. Even for A123. And, our suppliers don't share anything like a map of internal resistance v. SOC. We have to generate our own data to have any faith in how a given string of cells will behave under extraordinary loads, and to be sure that connection resistance is low enough at these currents.

Mixing two chemistries, in parallel packs, with an end goal of controlling the current split across a range of SOC, is a difficult problem for which modeling can only get you so close. I've modeled it, you can too, but testing will be needed to fine tune it. I'm staying away from the split pack idea if I can, for just this reason. If I can fit enough capacity in the vehicle at 6C to meet the max current need, I'd rather.

JR

[Speedy G]

Ok, we'll see what I end up doing, but there's time, since I'm only buying the batteries after everything else is done. Hopefully CALB and others are working on some super cheap, ultra lightweight and ultra powerful batteries in the meantime. My kit is getting picked up on the 24th so it should be in my shop maybe a month later due to import delays, etc.

One thing that may be of use is the fact that I'm using 2 separate controllers and maybe the second controller can start pumping serious current only after the throttle is over 50%. Since the second motor will be using belt drive, this may be the most efficient strategy anyway. I'm using a control system to read the throttle and act accordingly, so the added complexity is just a couple lines of code and an extra wire. I can probably play with regen as well to keep the two separate packs somewhat balanced in terms of charge, or even use an extra IGBT to have the pack with more current to supply current to the first motor. In any case, there's options other than siamese and two connected parallel packs. I also looked at ultracaps btw, but surprisingly they can't hold the current. I thought that's what they were good at.

On more question, battery related. How to cool the batteries? I was hoping to find some kind of aluminum extrusion that I could use for water cooling the batteries that could use water cooling, but no go so far. Any ideas on cooling CALB batteries? Would cold air being circulated above the batteries be enough, would air circulation on the sides do anything? Any ideas?

[John Rubicon]

Hi Speedy,

the two separate ACP controllers may have GFD circuits that fight each other on the same DC bus. Two separate packs, one for each controller, may be the only easy way that can work.

If you can, find a way to modify the Gen 1 pre-charge hardware to be friendlier. Right now you have to spin-on and spin off a fine-threaded MIL connector with an active mechanical interlock. Using the solenoid mechanical interlock signal to close a modern contactor on the outside, seems much friendlier. The Gen 1 had an early precharge failure mode that stressed the caps and caused them to fail prematurely. Maybe that was fixed before yours were built. Either way, a purely electrical pre-charge would help a lot. You do not want to leave the pack connected when the vehicle is to sit for long periods.

I have used a small film resistor to allow paralleled packs to come to equilibrium with each other when not connected to the inverters. May not work with the ACP GFD though.

I'll try again to dissuade you: the 10C discharge you seek from plastic-cased 100Ah cells (Calb, Winston, others) will kill them pronto. Even 5C pulse is pushing it a little. If you can afford them, the CALB CAM series with the metal jackets, non-conductive mesh cell spacers and a stirring fan will probably be OK. Water cooling the surface of a polymer jacket cell really doesn't work very well. Too much thermal resistance. Plus you have to trust your plumbing a lot to risk moistening the high-voltage :-0

EV West may have some liquid cooled battery modules made by Tesla. 18650 clusters with a cooling loop built in. These would be used items taken from dismantled EVs.

What sort of BMS are you planning?

JR

[Speedy G]

I think Ed might've just taken out the cap GFD circuits. The guys at ACP said "the capacitor control system" was missing. I still have no clue what that is, but it might include the GFD circuits. I'll have to take a look.

Actually I'm right there with you on the CAM cells, which is why I was thinking of just getting 110 CAM (70Ah) cells for the first motor and for the second motor, get some A123 cells(30Ah or less). I was looking at the ANR26650M1B cells (like 550 or more of them). I'm really hoping for the new CALB cells, and maybe the new pouches from A123. I can have several gas pedal profiles, so on in "insane" mode I'll be hitting the CAM cells to 7C and the A123s to 20C (~100A per cell). On the regular profile, I can do 3C-4C on the CAMs, which will still give me almost full horsepower, just not full torque, and drive the A123s at 10C-12C. I'll have to do some calculations to see what the optimum gas pedal profiles would be.

As far as the BMS... Sounds like a complicated proposition. I really like the ligoo displays, but honestly that's like saying I want to buy a car, a red one. The rest of the details are just beyond me, especialy since these systems are expensive, but they're also Chinese. So am I going to spend 3Gs on something to make my batteries more reliable, but it may not be reliable? That's why I was thinking of just monitoring voltages and manually bottom balancing. If you or anyone have any input, it would be greatly appreciated.

[Bob_n_Cincy]

As far as the BMS... Sounds like a complicated proposition. I really like the ligoo displays, but honestly that's like saying I want to buy a car, a red one. The rest of the details are just beyond me, especialy since these systems are expensive, but they're also Chinese. So am I going to spend 3Gs on something to make my batteries more reliable, but it may not be reliable? That's why I was thinking of just monitoring voltages and manually bottom balancing. If you or anyone have any input, it would be greatly appreciated.

I will be top balancing during every charge cycle.
That is the best way in my opinion. Been doing that way since my first lithium truck back in 2008.
The harder you push cells, the more important balancing and monitoring is. As you push them harder, the center of your packs will get hotter.
Bob
38766

[Gary Livingston]

Some chemistries are a bit fragile when it comes to balance, like RC Lipo. My opinion for LiFePo4 is to bottom balance and undercharge. I set mine to 3.45vpc. This will also prolong the life of the cells (under charging that is) No BMS (balancing) but BMonS system can be as simple as a split pack comparison. If you have a well balanced pack of cells, this will work best. You can go either way however, bottom balancing has an advantage related to running them to empty. If they are bottom balanced, you can drive the car till it wont move any more and since they all hit bottom at the same time, there is no damage. "bottom" can be defined. Top balancing will cause them to run out at slightly different times since capacity varies a little bit. At this point you will be driving several hundred amps through an empty cell and kill it. The top of the charge voltage adds almost nothing to the capacity if you study the charge curve. It just isn't worth it. Additionally, and these points all get hotly debated, BMS's have been responsible for he majority of thermal run away events, particularly when they control the charger cut off. Over charging is the most dangerous thing you can do. If you choose to use a BMS and actively top balance, please have a redundant control circuit to monitor the pack voltage and disengage the charger. This will work ok. IF not, don't be parking it in your garage.
Most of the original thinking has been BMS and top balancing. . .but now, most folks are not going this way. . . and there have been no issues. I've run my CALB pack at 10C many many times and never had balancing issues. I use to be paranoid about it and checked the cells constantly. It's gets rather boring after a few years. They are just stable.

[Bob_n_Cincy]

Hey Gary,
Thanks for your opinion. Lets leave the BMS/balancing discussions to the EV forums. Do you Agree?
Bob

[Gary Livingston]

Hey Gary,
Thanks for your opinion. Lets leave the BMS/balancing discussions to the EV forums. Do you Agree?
Bob
Hey Bob.
Yes, for sure. There has been plenty of discussion in other places. You are quite the gentleman. :)

Gary

[Speedy G]

Haha, that's an interesting discussion. The thing is I'm more interested in the how to balance than whether top bottom, left or right ;) Do you guys have preferences in brands of BMS's or do you guys build your own BMS or BMonS?

Gary what do you use to bottom balance? Do you balance them by hand (down to say 2.75V)? What do you use to discharge the cells? What's your bottom hard limit when loading the batteries? 2.8V? Also, since you've used the A123 cells how do they compare in terms of balancing?

Bob, what systems or procedures have you used to top balance? Do you balance by hand? Any preferred BMS?

John, do you have any input on the subject?

[Gary Livingston]

Haha, that's an interesting discussion. The thing is I'm more interested in the how to balance than whether top bottom, left or right ;) Do you guys have preferences in brands of BMS's or do you guys build your own BMS or BMonS?

Gary what do you use to bottom balance? Do you balance them by hand (down to say 2.75V)? What do you use to discharge the cells? What's your bottom hard limit when loading the batteries? 2.8V? Also, since you've used the A123 cells how do they compare in terms of balancing?


The first time I ever did it, I simply connected them all in parallel and left them for two weeks. It may not be the best way, depending on state of charge. While voltage isn't a great indication of state of charge for LiFePo4 in the middle of the charge state particularly, it still is somewhat relative if measured to a couple decimal places on batteries that have not seen and load or charge for a while. The next time, I ran them fairly low in a series pack and used a large resistor to bleed them down. 2.7 volts is a good number and nicely into the knee of the discharge curve and close to empty. Now I use a Powerlab 8. I have two of them actually. You can also automate the process with a small Lightobjects voltmeter with programmable outputs and a large resistor. Jack sells this stuff on the EVTV web store if you want to get it all in one place. The voltage is a bit "spongy" meaning you may have to cycle them a couple time to get them to stay where you want. I like to use a volt meter that reads three decimal places. The powerlab is nice for checking capacity as well.

I have top and middle balanced the same way also, manually.

The only BMS I ever used was on AGM lead acid. Floodies dont need anything, but sealed lead does. . . as you do not want to boil them to balance. In fact, a lot of the beliefs on this subject are a hang over from lead acid days. Ive heard good things about the Orion and the Mini-BMS . . but honestly, I'm not the best one to ask. A BMS will eventually balance your pack after cycling it some number of times. It may take a while though as most of them do not shunt a lot of current. One other point to be aware of if you use one is the parasitic draw. There have been a number of packs ruined by leaving them unattended over long periods and the BMS itself draining the pack. (Sorry Bob, just raising the point for awareness sake) :)

As for load voltage. . . it's an interesting topic. The voltage when there is heavy charge or discharge isn't really the voltage. It is, but it isn't. I don't charge more than 3.5 vpc, actually usually 3.45vpc. That said, if the charger was still in CC mode, I wouldn't worry too much if the voltage was higher. Of course to get it higher means a lot of current and there could be limits there. Same on discharge. The voltage can sag quite low, but the "real" voltage of the cell will show when at rest. So.... if you are not already confused.. . . all batteries will give their peak power at 50% of their nominal volatge . . . as a general rule. So, if you the ability to program voltage under load and you are using LiFePo4, I would set it to 1.6 or 1.7 vpc. Resting voltage limits are quite handy also, to progam a "limp mode" meaning. . git ur arse home. :)

The good news is that the cells now tend to come much closer in capacity than they every use to.

Cheers,
Gary

[Bob_n_Cincy]

The thing is I'm more interested in the how to balance than whether top bottom.

Bob, what systems or procedures have you used to top balance? Do you balance by hand? Any preferred BMS?

John, do you have any input on the subject?

I have used 3 systems during the years. The first one was a purchased system. The last two I designed and were proprietary to the companies I was working for.

On a new vehicle (96 cells) we would charge the up 3.6v in parallel before instillation into the vehicle.

One of the hard things to do in any EV was replacing one 700 AH cell into a half charged pack and trying to match it to the rest of a pack.
The replacement cell could be off by 100s of amp hours and take weeks to get in line.

To answer your question on how to balance:
To balance, you must bring each cell to the same state of charge. (SOC)

Bottom balancing is done by individually draining all the cells until they are empty. (2.7v)
Typically using a controlled bleed resistor on each cell while the pack is not being used.

Top balancing is done by individually charging all the cells until they are full.(3.6v)
Typically using a controlled bleed resistor on each cell while the pack is being charged at very low current.

This website has a lot of good information on BMS systems.
http://liionbms.com/php/index.php


Bob

[Speedy G]

Awesome info guys, thanks a lot.

Gary, good to know about the load voltage, it's something I was thinking about. So it's hard to be 100% safe on full load, since sag takes you way below safe full discharge voltage. The ACP controllers shut down below 220V, so with 110 cells that would be 2V, we'll have to see what we do about that. Btw, the powerlab 8 looks very helpful.

So I'm thinking it's possible to conceive of a BMS that could do bottom or top balancing with the same hardware. After all, it sounds like you're always draining to a voltage whether you're top or bottom balancing. Also, I can see how a BMS can kill the batteries either way. The easiest way to power a BMS drain circuit is with the battery it is "clamping". So if you're bottom balancing and forget to charge, oops, your battery's dead. Also, on the top side, it's easy to exceed the drain current used to "balance" a battery top side using any charger. I just saw that the Ligoo BMS uses 3 channels of 300mA battery each for balancing... 300mA and I'm charging with 20kW? Even at 360V, that's 55A, balanced by 300mA?? No wonder it takes weeks to "balance" a new replacement cell. I realize the voltage is "spongy" due the hysteresis in the charge-discharge cycle, but still, I would think balancing current capacity should be higher... Interestin topic, we'll see what I end up doing. I'll probably bottom balance initially, and later see what I can do to automate the balancing.

[Bob_n_Cincy]

Awesome info guys, thanks a lot.

I would think balancing current capacity should be higher...

Hi Speedy
I have designed BMS boards with 2 amp max bleed.
If one low cell, you might have 95cells x 3.6v x 2a = 684 watts you need to get off the circuit boards and out of a sealed battery box. Can you say, Easy Bake Oven.
Bob

[John Rubicon]

Hi Guys,

I inferred from Bob's post a hesitation to open up the BMS religious discussion, so I waited. It can get testy ;-)

I am not a fan of bottom balancing, but then again, I've been disappointed by batteries too many times, and want to have information to use in vehicle control. And I'm the kind of guy that drives his gas car down to the "E".

Plenty of people make bottom balancing work for themselves just fine. And it's inexpensive(!)

Bob, you've used 700Ah cells too? Cells the size of briefcases seldom have the same characteristics in my experiences. There is no practical accelerated life testing for large cells like these. One thing the Tesla approach does have going for it - massive parallel redundant current paths and uniform cell resistances.

I've experienced about a dozen systems and they all have their kinks. I did like the Ligoo system's UI that Speedy pointed to, but I couldn't tell a thing about how it works. bit resolution and accuracy, connector type, CAN chip, isolation, I needs to know. Maybe I didn't look enough.

I'm currently working with a couple different folks on a wireless BMS systems. The tech seems to work very well.

JR

[rtz]

I say keep it simple and no BMS. When you buy your batteries; drain down each one to the exact same amount. Now wire them up and charge up your pack. Now you are set. Never, ever, discharge below a certain amount, and never, ever charge above a certain amount.

Read this in full for the exact details to the one time procedure: http://media3.ev-tv.me/cellcare.pdf

Any more questions call, email, or stop by Jack Rickards shop(see webcam) and talk to him directly about it: http://evtv.me/

[rtz]

the kind of guy that drives his gas car down to the "E".


Keep in mind that most(all?) in tank fuel pumps use the fuel to keep the pump cool. So in the hot summer when that pump is running in air compared to if the tank was full?

[Speedy G]

Well, guys, it seems my date has come. I have kit #525 (red). The FFR date for pick-up was dec 27, but I had to get the kit from FFR to Colombia, legally, and complying with all of our stupid regulations. The funny thing is that the windshield was the only thing that needed extensive paperwork, so I told the FFR guys to ditch it and to send me the kit without it. It's just another item I'll have to source locally.

In any case, this is just an update to say that my kit will be getting here on Saturday morning, so I should be able to get my hands dirty after Easter Sunday (we have the week off). I'll post the pics on Saturday.

[Frank818]

Yes sir! You can finally put your hands on it (soon). Will you pet the panels and cuddle with the frame? :)

When you say "windshield", do you mean only the glass or both the glass and FB surrounds? I believe only the glass.

[Speedy G]

So my kit arrived on Monday. It took a while longer since I was out for vacation over Easter (love the Catholic holidays). The stuff arrived in ok shape. One thing I do have to highlight is how unhelpful Factory Five was with import requirements. They absolutely do not even move a finger for you when an odd requirement is needed. Mine weren't even that odd. In fact they don't move a finger at all in terms of export logistics. They don't know what export documents are, and they will not change anything in the kit so that import requirements are met. My requests to Dan Golub were simple. I needed a simple commercial invoice (typical document required for export, internationally accepted), and I cannot import automotive glass since it needs a certificate from manufacturer that shows that it complies with local requirements, BEFORE importing. Neither was possible. To my surprise, when I opened the box, after sending 5 emails and talking to Nate over the phone, there was the windshield glass. The same one I said needed to be taken off the chassis before packaging in the crate. Worse than that, the certificate of origin didn't come with the kit, so I had to pay an import tariff of 10%, while that could've been avoided if they'd sent it with the kit. In other words, the kit looks great, but the factory five staff were extremely unhelpful. Luckily things went well, and our customs officers are as inept as Nate and Dan. What should've happened is that the kit should've gotten stuck at customs for trying to import automotive glass without a prior import permission. That would've taken at least 6 or more months to solve. The thing is that I don't really know if the glass was broken before it got through customs, if it was broken to clear customs, or if it was broken after it cleared customs. If it was broken prior to clearing customs maybe I just got lucky. However, if it was broken after it cleared customs, it's a clear violation of import restrictions and falls under the category of technical smuggling, for which you do time down here. In any case, I would've expected Factory Five to be way more helpful. Every country has different import barriers and tariffs and these guys will not help, AT ALL to meet them.

Here's some pics:

My shop before the kit came:

40414

The 2 forklifts and operators:

40415

The unloading from the truck:



Transportation to the shop (50 ft):

40416

The tiny box in the shop:

40417

A video of the innards of the crate:


http://youtu.be/p0XtMVyAfpg

Pic of the innards of the crate:

40419

Scratches on the upper door panels:

40418

Btw I blame the problems of the state of the kit on the shipping company. The crate looks extremely well made and the scratches were probably made between the port and my shop. The shipping company had to open up the crate, check and inventory it and repackage it.

[Speedy G]

I can't wait to try to fit the drivetrain in there. I think it may be one of the first things I do. It sucks having to do inventory, take apart the crate, and organize all the boxes. Until I do that, I won't be able to start looking at the chassis since I have little room. Btw I noticed the fibreglass is really thin. I was expecting something thicker, like in a boat. Originally I was thinking of painting it orange, but the red color is great. All I need to do is fix some of the scratches on the gelcoat and polish it... hmmm... but where to store it...

[Frank818]

Nice shop, how long is it?

[Speedy G]

It's something like 9m x 3m (30ft x 10ft), plus the bathroom. It's small, but I have plans to set it up properly. I have a metallic workstation coming and 2 wood surfaces coming. Also, I'm putting in 2 more lights. You gotta remember this will be an electronics shop as well as a mechanical one. The best feature are the skylights. Whoever made them, they left the structural steel rebar and took out the concrete. That means I can hang heavy objects from the ceiling by just clipping the hoist unto the steel rebar. Also, I have so much light during the day that I don't even need to turn the lights on. I'm figuring out what to do with the fiberglass panels, they take up so much space....

How's the welding coming along? I'm thinking of taking it up as well. Nothing structural initially, but maybe the battery boxes (aluminum though).

[Frank818]

You'd start welding aluminum?

As far as steel goes, I would have been the worst a**hole in the history of Planet Earth to not buy my welder and not learn how to weld. It serves me so well, my project would be crap or cost me a lot of welding money if I hadn't bought that machine.

[Speedy G]

K so I unpacked and did my inventory. Man, that crate takes quite a bit of effort to take apart. It took me like 2-3 hours just to tear down 2 sides of it.

Things look good, nothing missing so far, although I wasn't able to identify all the parts exactly. Is there a thread with pics of all the difficult to identify parts?

The next issue is what to start with. It looks like aluminum sheeting stuff, then suspension, steering, brakes, motor+gearbox, batteries + cabling, then interior and finally body panels... Actually, since my shop is so small, I might have to finish up the front with body panels in place, then go over to the other end, take off the rear body panels, put in the motor, etc and put back the body panels. I just have no place to store them. So no riding the go-kart in this project...

In any case, the plan is to get this puppy running enough to get it registered, then modify it with larger batteries and improved electronics. That means initially all I need is batteries for a 20km range (13 miles). For this I'm considering A123 batteries, about 550 ANR2550m1's. That's 5 parallel packs of 110. They'll give me 320V nominal, 50 amps continuous (50 Amps * 350V=17.5kW). At 17.5kW they'll only last 15 minutes though. However, for the future, they're capable of 120A*5, so 600 A in a burst of less than 10 seconds and with enough cooling going on. Coupled with some CALB batteries, I should be able to get the 400hp in 10 second bursts.


So... Problem #1 Alu sheeting, tools and fasteners:

I got some cool tools. 18V Bosch drill/driver (had already), Bosch PS10-2A drill/driver with tilting head and torque limiter, Campbell Hausfeld Commercial CL153900AV Rivet Gun, and 2 rivnut tools from mcmaster (for 10-32 and for 1/4"-20).

I've also been looking at the rivnut problem. Which rivnuts, which material, which tool, which rivets. From reading all over, FFR sends us 1/4"-20 riv nuts in aluminum.

The following are the best threads I found. I wish we had a sticky talking about fasteners:

http://thefactoryfiveforum.com/showthread.php?15098-Alternate-rivnuts

http://www.mcmaster.com/#stainless-steel-rivet-nuts/=xguw6h

http://thefactoryfiveforum.com/showthread.php?16457-Fasteners-for-body-panels

There's a couple of things we can conclude. Mechie3 talks about the size of the rivnuts being too big to mount body panels. Also, he used steel rivets which seat better. I might add that steel has better fatigue characteristics than aluminum.

Also on the galvanic corrosion issue, the following page illustrates it pretty well:

http://www.aluminiumdesign.net/design-support/aluminium-corrosion-resistance/

Aluminum corrodes steel if they touch and have some kind of electrolyte (poluted water?). So... what's better? If I use steel rivets, they'll leave nice rust marks on the aluminum plates in the long run, and the fasteners will eventually fail (although the plates will be powercoated, so it won't be that bad). If I use aluminum rivets/rivnuts, the frame will corrode(and I can't powercoat the inside... Easy... Either steel or stainless rivets/rivnuts.

Pics of the shop as it is currently:

42461

42462

Speedy G

[John Rubicon]

K so I unpacked and did my inventory. Man, that crate takes quite a bit of effort to take apart. It took me like 2-3 hours just to tear down 2 sides of it.

<snip>
In any case, the plan is to get this puppy running enough to get it registered, then modify it with larger batteries and improved electronics. That means initially all I need is batteries for a 20km range (13 miles). For this I'm considering A123 batteries, about 550 ANR2550m1's. That's 5 parallel packs of 110. They'll give me 320V nominal, 50 amps continuous (50 Amps * 350V=17.5kW). At 17.5kW they'll only last 15 minutes though. However, for the future, they're capable of 120A*5, so 600 A in a burst of less than 10 seconds and with enough cooling going on. Coupled with some CALB batteries, I should be able to get the 400hp in 10 second bursts.
<snip>

Speedy G

Hi Speedy,

take a look at what John Metric at Ampaholic.com is selling for his drag racing friends. these Cobalt cells put our 100C (!) Your "burst" pack would be very light.

In case the site is down, I have a nice chart relating nSmP battery pack configurations to current outputs from his site. PM me if interested.

The old ACP drives only put out rated power at 336V, so 320VDC will seem anemic, I suspect.

All the best,

JR

[Speedy G]

Nice!! I'm very interested. It's just what I need!

[ninjanick]

Very interested in where you will eventually place your battery packs/boxes. I'm having a hard enough time stuffing 96 CALB CA 60aH. The 72aH cells package better, but not much data/real world usage yet so I'm hesitant. Are you worried about mix and matching capacities if you use your A123 pack combined with a CALB pack?

[Speedy G]

Dude, I'm waiting for you to fit your batteries to give me an idea :D. 96 cells is crazy and 110+booster pack is next to impossible. We'll see! Post some pics! Btw, I'm definitely using the tranny tunnel for batteries, even if I have to modify the structure. The idea is that the CALBS are setup like Eric's with the addition of the tunnel, and maybe there will be additional batteries on top of the other ones (in the back up to 60-40 weight distribution). I'm also thinking the booster pack will be in front of the front axel and with some serious active cooling (think copper/alu plates to hold the batteries with recirculating transformer oil and a heat exchanger in front). I haven't calculated the volume for the booster pack though.

You gotta remember I have 2 motors and 2 controllers. I can have a pack and motor for distance and another for acceleration/braking regen. That doesn't mean I'm not going to try to combine them with close monitoring (watching currents coming out of each pack). If they don't balance well, I could add an IGBT to the CALB pack to limit its current output. So how do I control which motor gets what torque control signal (i.e. gas pedal voltage) if I split the packs? I'll be using an onboard ARM computer (cubieboard) to manage that. The computer reads the signal from the pedal, then decides which motor does what. The idea is that the CALB pack never goes over 4C or even 2C in normal city driving. The other pack gets all the regen and handles the voltage peaks. The computer also decides which pack gets the regen. In the real world you rarely accelerate for more than 15 seconds, so a pack that can take 600A for that amount of time is all I need. In any case, that project is at the end of the rainbow. I still have to make this thing move.:cool:

[ninjanick]

Fair enough ... it's definitely been a struggle. The design doesn't close all the way now, but I hope after I modify the frame to fit the engine, I can get a better idea of how many batteries I can stack in the gas tank area. I played with the idea of installing batteries in the center tunnel area, but I'd only be able to fit a few. Even then I'd have to raise the height by a few inches. There's room forward of the gear shifter, but I was thinking that the increased resistance of the interconnecting cables made more sense to try and consolidate battery packs to as few locations as possible.

[ninjanick]

Will the Cubieboard also switch charging or do you plan to have two chargers for each pack?

[Speedy G]

That's the thing, my motor controllers each has a battery pack charger. I can plug each to a 110V plug or up to 250V. Version 2 of the controllers even has a UPS mode, meaning you can hook up your house to the inverter and if you lose power, the battery pack will drive your house for a while.

The cubieboard has other tasks though. I'm thinking it'll be monitoring the batteries, managing traction control, and eventually, it'll rpm match the tranny with the motor for automated shifts. It'll also drive the automated shift actuators. The idea is to use the tranny in 2nd gear until I can get myself to spend on a dog engagement kit for the subie tranny. Once I do that, I'll be paddle shifting a dog engagement tranny with no clutch. I'll release all the code and schematics on the board once I'm done.

Speedy G

[Speedy G]

Hey John,

I looked at the Cobalt batteries out there (site still down though, so not John Metric's ). It looks like those suffer from thermal runaway. That means monitoring the temperature of every cell so it doesn't come close to 130C. I'm not sure I want that in my car. It's like knowing the flash point of gasoline is 280C, and running your turbo down pipe 3 inches from the tank... too close for comfort. Do send me the specs, but I think I may go with the A123 cells. The burst pack will only weigh 80 lbs with dimensions of 1.6ft x 1.6ft x 1ft.

Btw, I think it's awesome that the fastest Miata on the quarter is electric.

P.S. The site is up actually. It's ampahaulic.com. I sent them an email. I'm thinking their pack will go for something like 5 grand which might be cheaper than the A123s.

Speedy G

[Gary Livingston]

Nice!! I'm very interested. It's just what I need!

No it's not... :) Don't be mixing LiFePo4 with RC Lipo.

[Gary Livingston]

Are you worried about mix and matching capacities if you use your A123 pack combined with a CALB pack?

Booster pack is used in parallel. Capacity adds. Make the voltage the same. One charger. It looks like one pack to the charge and the discharge device. No need to manage anything. . . except perhaps heat on the booster pack if u bust it a lot.

[Gary Livingston]

RC Lipo is the best place to go for 1/4 mile power. I would never put it in a daily driver or a hot rod. Maybe in track car. . . but this stuff does need a BMS..... and a good one at that. And I wouldn't charge it in my garage.... at night. :rolleyes:


Hey John,

I looked at the Cobalt batteries out there (site still down though, so not John Metric's ). It looks like those suffer from thermal runaway. That means monitoring the temperature of every cell so it doesn't come close to 130C. I'm not sure I want that in my car. It's like knowing the flash point of gasoline is 280C, and running your turbo down pipe 3 inches from the tank... too close for comfort. Do send me the specs, but I think I may go with the A123 cells. The burst pack will only weigh 80 lbs with dimensions of 1.6ft x 1.6ft x 1ft.

Btw, I think it's awesome that the fastest Miata on the quarter is electric.

P.S. The site is up actually. It's ampahaulic.com. I sent them an email. I'm thinking their pack will go for something like 5 grand which might be cheaper than the A123s.

Speedy G

[ninjanick]

Booster pack is used in parallel. Capacity adds. Make the voltage the same. One charger. It looks like one pack to the charge and the discharge device. No need to manage anything. . . except perhaps heat on the booster pack if u bust it a lot.

Are you worried about internal resistance differences between cell technologies/manufacturers? I'd imagine you'd be cycling the lower capacity "booster" pack quite frequently.

[Speedy G]

Well, I think Gary is referring to the fact that those cells probably aren't very consistent, and they also suffer from thermal runaway. If you heat them up over 130 degrees celcius, they'll catch fire. Since they're not very consistent, you could discharge one at 100C and it would be ok, and the next could heat up to 130 C and blow up. I'm not sure why he calls them RC LiPo though.

I was already thinking the A123s look like a better option. The only issue is where to get them. I've only seen 26650 batteries out on the market, without screws. Soldering 550 cells in series is not quite the assembly job I wanted for this car. Gary, any clue where i can get them?

[ninjanick]

Have you looked at Headway cells? They have screw terminals and might be an easier cylindrical option to assemble. If you are sold on cylindrical, have you looked at bulk buying Samsung or LG 18650s? They seem to be more readily available than the Panasonic option.

[Speedy G]

Can they do 50C though? My main cells will be CALB. The booster cells are the ones I'm worried about.

[ninjanick]

The Headway 40152 cells are 15aH with a max discharge or 10C whereas the 38120 cells are 10aH with a max discharge of 10C.

[Gary Livingston]

Are you worried about internal resistance differences between cell technologies/manufacturers? I'd imagine you'd be cycling the lower capacity "booster" pack quite frequently.

Not worried about it..... that's what makes this method work. When the draw is low/slow. . . the discharge is balanced. When you stomp on it, the lower resistance booster cells try and support the voltage (drop) and therefore give up more current. When you let off. . . they recover with the energy from the range cells. So, you need a strong cycling cell capable of higher C rate like ones used for hybrid packs. . .like the A123 nano cells. Headways are oookayyish, if you spend the time to sort out the week ones. That's the problem. lots of guys build nice packs with them and loose 2 or 3 % of their cells.
IF anyone wanted to use RC lipo in a car, the only place I would get it from is a chap in England who spends a lot of time weeding out the weak ones. . . even then, I wouldn't trust it for a daily driver.

[ninjanick]

Are you referring to the A123 Iron Phosphate batteries? I've only really seen them on Ebay. I made a small battery pack out of Dewalt cells for my motorcycle. Worked great for a few years till I moth balled the bike in the garage and let it drain completely. I imagine putting a cell pack of those types would be expensive. Do you calculate total depth of discharge for the booster pack for the amount of power/time you need to size the booster? I would imagine if too small, you'd overdischarge the booster?

[Gary Livingston]

Yes, A123 LiFePo. I have used the 32157's and the 32113's both rugged cylindrical cells. The capacity of the pack and C rate will determine the extent of the boost. You will never overdischarge the booster pack . . . unless you overdischarge the whole pack. Just think about it. . . the higher C rate cells are sitting at the same voltage as the rest of the pack. If you draw on the whole pack at a high rate, the lower resistance cells will prop up the voltage of the pack and since they sag less will give up a high percentage of the current. But as the booster pack gets closer to empty the main pack will take over. The net result is just less boost. You will never drop below what the main pack delivers.

[Speedy G]

The thing is that you do have to watch out that you don't draw too much current from the main/booster pack. Say I draw 600 amps out of my 110sp6 A123 pack and 400 amps out of my main pack (CALB). Once most of the juice is gone from the A123 pack (trying to keep the voltage up), the current comes out of the main pack. So if my main pack was initially doing 4C, now it's doing 10C. All I'm saying is that it's good to know where your current is coming from if you do use a booster pack so as not to damage your main pack. It could also happen that if your batteries are too different, the booster could supply say 8/10 of the current, and maybe that would be too much, even for the booster pack. That's why I'm not totally sure what I'm doing yet. If the A123's prove to be "compatible" with the CALBs, I may use the main and the booster battery packs in parallel. If they prove too different in terms of resistance, then I'll use my two controllers and software to determine which pack and which controller is supplying the current.

[Gary Livingston]

True enough, . . but all you really need to do is program a voltage limit under load. Decide what voltage you will allow the pack to sag to.
There is no issue with "compatibility" , just match the voltage. A123's are actually 3.3 nominal so even less of an issue depending how many you put in the pack.
As I said somewhere before,. . . I wouldn't go down this road of main and booster pack if I was starting fresh like most here are. I did it because I already had the range pack and wanted to prop it up. Try to select a battery that will give you what you need without having to build two packs. CALB are great range cells, but they aren't high performance and they're not the only cells.

[Speedy G]

K, a bit of an update. Remember I have twin 2 year old girls so my time is scarce. I'm mainly confined to 3-4 hours a week if that on Saturday mornings. So what's up? Well, the first thing is that I finished the drilling and I've attached a video from part of it. It's essentially repetitive and mind-numbing. Here's a video from the first day. After that it's all looks the same:


https://youtu.be/E9Nmw-YbaWw

There's a few things to be learned from it:

The first is that drill bits matter. I tried regular high speed steel, titanium coated, but ended up using cobalt steel drill bits. They're expensive, but things get done faster and better with the proper tool. Titanium ones are ok, but they don't last forever.

The second thing is that FFR really does a poor job with aluminum forming. Aluminum has memory, so when you bend it to 90 degrees it'll probably end up being at 70 deg when you try to install it. They obviously don't take this into account. That means the dead pedals are extremely tough to install since nothing really fits. Add to that that the steel sheet flooring is warped due to welding, and what you get is essentially a solidworks wish it were true design that doesn't at all apply to the reality of the build. On top of that, it's supposed to be water tight! Not surprised, but it shows there's definitely a long way to go in terms of engineering design. Someone said we're not building BMWs, I can see that now. Then again the fun part is fixing it my way (not yet)... Here's a pic of what I'm talking about:

47140

Check out the space below the corner of the dead pedal. Also, check out how I had to bend the panel so it would fit. You can see the large vertical panel is curved since I couldn't find a way to bend it to beyond 90 degrees (metal table gets to 90 degrees). This is after shaving off a few of the parts with sheet metal shears btw.

Speedy G

[Speedy G]

Soo... A few things that might be useful to people:

A good place to find subaru parts http://parts.andersonsubaru.com/. They have the standard subaru catalog drawings, but you click on the part and it takes you to the part number, etc. It's pretty well done, but they're not cheap. I found www.subarupartsdepot.com and www.quirkparts.com to be much cheaper. The best part of it is that andersonsubaru.com has hardware part numbers which are missing on most of the other sites I've checked. I bought the hardware from quirkparts.com since I found them after I'd already orderer most of the other stuff from subarupartsdepot.com.

Subaru parts list for the front suspension (missing the splash guard or back-plate):

47146
47143


Subaru parts list for suspension hardware and rear suspension w/o knuckle or disc brakes:
47144
47145

Also Fastwrx.com sells hardware kits for the rear suspension:

http://www.fastwrx.com/products/subaru-gd-rear-lateral-link-hardware-kit
http://www.fastwrx.com/products/subaru-oem-lateral-link-to-knuckle-bolt

[RetroRacing]

So far, we have used NONE of the alum supplied in the kit. first of all, the numbering/identification system did not exist. Secondly, when we did try to use a bent piece, we noticed cracks forming at the bend, which didn't make us happy.

[Speedy G]

Also, I've been trying to install the 2015 STI steering rack. The differences are barely noticeable. It looks like the diameter of the rack is larger than the 2006 rack since the bolts provided are too short. Also, the driver's side needs a couple of washers or some kind of shim on one of the screws to level it out. On the passenger's side, you could use the provided bracket, I guess, but I bought a nicer bracket from Hindsight. Here's some pics. I took the liberty of using Hindsight's pics for the regular '07 rack to compare:

47153

47154

47155

[Speedy G]

I've been looking at batteries again. I think the perfect battery for the 818 AC high voltage motors (~360V ) is the CALB CAM72FI. Why? It's good to ~230Hp (~576A*300V), has decent range, and fits replacing the gas tank and the center tunnel with a modification of the rear firewall and a redo of the center tunnel. I'll definitely be using 110 CAM72FI cells for my range battery (main motor), and eventually for the secondary acceleration motor, a set of 110 A123 20AH pouches. The 110 CALB batteries have a nominal voltage of 352V and 302V at 8C (way less than a 10s pulse under 1/4 mile accleration). Also, the way they're constructed makes them easy to cool using fans since the batteries aren't touching each other.

The new tank has a section that's 20cm deep, and the thin part is 10cm. The batteries are 13.5cm wide, so redoing the rear firewall means the passenger gains some leg room as well, but the driver maintains decent leg room. The tank and the center tunnel fit 80 batteries. The remaining 30 can easily fit in the back on either side of the tranny, or forward of the firewall. This way, most of the weight is distributed optimally. The A123 cells can later be added depending on where the additional weight is needed, but these don't need that much space since they'll be only 20AH.

Replacing the center tunnel makes sense if you're using a Tesla style 1 gear gearbox of if you go for an automated 5mt (Mastershift, etc) since you won't have space for the shifter cables. I'll initially be driving only in second gear which is the equivalent ratio of a Borg Warner egeardrive tranny (8.28:1 vs 8 wiith a 4.11 ratio), so it won't be a problem for me. The center tunnel is 13.5 cm wide, just like the batteries, so the modified center tunnel will only be maybe an additional 1cm wider. However, the height will increase by like 10cm (~2.5 inches) to 25cm, which isn't much when you compare it to the tunnel in the original MR2.

The weight for the 110 CAM72FI cells is 209kg (459 lbs). That sounds like a lot, but the subbie engine plus a full tank of gas weigh around 400lbs. A single one of my electric motors is 100 lbs, and the controller is probably 65 lbs, so It looks like mine will weigh around 200lbs more than a regular 818s build.


Speedy G

[ninjanick]

I've been trying to estimate voltage sag and was wondering how you came up with 50V at 8C. Was this actual testing? I tested a single CA 60aH cell with a PowerLab 6 and it measured 0.9mohms. Not sure how much better the FI technology is, but <0.8mohms is pretty good if including battery cables, bus bars, fuses and hardware.

I assume you are using the plastic spacer ends for your batteries. How are you constructing the battery boxes? I'm planning on 1/8" Aluminum sheet metal with cross braces to secure the batteries in place to ensure they don't jossel around.

[Speedy G]

Hey, I thought you'd chime in since you've been talking about batteries for a while. I just took the sag value from evtv.me (Jack Richard), he's also tested the CA cells which I think you have, and they seem to be able to do 10C. Here's the CAM72FI writeup:

http://evtvindex.blogspot.com.co/2014/05/may-16-2014.html

There's a writeup also for the CA cells:

http://evtv.me/2012/09/battery-joy-and-the-car-guy/

Yes I'll be using the plastic spacers. My first idea was to reuse the gas tank for the battery but my tank has a different depth on the driver and passenger sides (10cm vs 20cm). I might still use the tank, modify the front to make it around 15cm deep and just brace the batteries together in packs of 60cm or around 20 batteries. I'll then attach the packs of 20 to the outer shell (tank). But then again, the aluminum sheet metal idea like Erik's sounds good.

Also, I've been looking into battery cooling. I found this thermal image:

http://jes.ecsdl.org/content/161/14/A2168/F7.expansion.html

What that tells you is that if you cool the cathode, you'll effectively cool the whole battery and it'll also make the temperature more homogeneous. What that translates to in my book is that I'll be cooling the batteries from the top, which makes sense anyway. I'll be adding fans to extract the air from each end of the pack, and I'll have air intakes after every battery, not sure where yet, but the idea is that cold air gets to every cell.

Speedy G

[ehansen007]

Not to hijack this thread or anything but this part of the build was the most important and most time consuming. Securing the batteries properly is paramount. From experience I can tell you that building your own boxes with aluminum is the best way to do it. I'm not sure I'd use the gas tank as you're going to want to secure the top of the batteries with something running across in case you ever go upside down. The tank is flimsy and may not have enough material to adequately secure the batteries. Also, they aren't thick enough to countersink the tapered allen bolts that secure the box through the bottom to the frame. You could run lugs at the bottom I'm sure but it will warp that metal. You'll also want to drill a few holes in the bottom for drainage in case, god forbid, any water gets in there, you'll never get it out! :)

EV West was very adamant about this and showed me how to do it right. Cardboard goes a long way for sure and will help you figure out how and if boxes will go into position once built. Simply putting the batteries in configuration and moving cardboard around it worked great.

Running the batteries up against each other wasn't a bad thing as they never got hotter as a pack as to surpass the mfg specs. Even when dumping 1000A at 10-14C at the track! But again, secure them properly as you don't want those arcing out in a crash or flip. Hope this helps.

http://i897.photobucket.com/albums/ac177/ehansen007/818/818%20BUILD/IMG_2456_zps2ec9d698.jpg

Then translating those into spec and given to a competent welder

http://i897.photobucket.com/albums/ac177/ehansen007/818/818%20BUILD/image7_zpsb6d13101.jpeg

Then adding the security

http://i897.photobucket.com/albums/ac177/ehansen007/1381592595_zps3f4f3e1f.jpg

http://i897.photobucket.com/albums/ac177/ehansen007/IMG_20131118_101035_zpsc0757faa.jpg

[Speedy G]

Hey Erik, thanks for your info. I've been using your thread extensively for battery and general info! At this point I think your build is the reference since non of us have finished ours. What about building an e-coupe?

In any case, I just got the dimensions for the CALB CAM72FI batteries with the plastic spacers: 248.5mm H x 138.4mm W x 34mm D. What that means is that I can't fit 40 cells in the tank space, but rather ~35, and 32 in the tunnel. That means I need to fit ~43 cells either in the front or in the back. Judging from Erik's thread, it might be easier to fit them in the back, ~22 on each side of the tranny.

The following image shows the CAM72FI cells with their separators:

47581

Notice the "partition fixer" has a way to attach it to the flooring. Also, the screws hold the batteries together and to the partition fixers.

[ehansen007]

That is pretty slick! Haven't seen that setup yet. And yes, there is a ton of room on each side of the tranny. SO much dead space in there. Looks like you guys know what you're doing so I'll just sit back and watch. And no, I don't have any interest in doing an e-car in the immediate future. I'd love to see the batter prices come down a bit first. I just want to drive my new cobra around a bit as well. If I did do another one, I'd do a hybrid for sure. Maybe electric front and a turbo hyabusa in the back or all of it in the back? :)

[Speedy G]

Hey, long time no write... Little progress, but some. I've been stuck mostly due to missing parts. It's really hard to finish a system if you have to assemble, check for missing parts, look at the crummy subaru drawings and part numbers available on the net, buy, wait, reassemble, repeat.

In any case, I've been assembling the brakes, suspension and steering simultaneously. Waiting on a few screws in the rear suspension, but I should be done by next week. The wilwood brakes are huge btw. They're going to look cool, and are definitely overboard.

As far as the steering goes, I'm going to need to mod the frame. I'm using the 2015 STI steering rack. It's almost a good fit, but not. Below are the pics. Although I could theoretically use the provided mounts and add a few washers to the driver side, rear bolt, as people do on 2006 wrx's that would tilt the rack in 2 dimensions. The drivers side would be more to the rear and higher than the passenger's side mounts. Sooo... I'm going to cut and make a new mount... eventually. Definitely before I race it. Here's some pics:

Here's the problem. The forward mount on the steering rack is way thicker than the aft one:
50794

That causes the rack to be further aft on the driver's side than on the passenger's side,
50796


and the driver's side is higher than the passenger's side, although it's not visible in this picture, but with a level it becomes clear:
50795

Since it's only the front driver's side mount, I think the easiest way to fix it is to cut and replace the mount on the frame. Also, on the second picture you can see that the plastic boot hits the frame, and that's without adding washers to the aft mount.

Speedy G

[Frank818]

You could weld spacers on the FFR mount to even out the fore-aft rack holes issue.

Was the use of a 2015 rack a necessity or the ratio difference was something cool you wanted?

[longislandwrx]

http://forums.nasioc.com/forums/showthread.php?t=2679348


speedy, see post 2, you need to make that spacer.

also seen in step 15 here:

http://forums.nasioc.com/forums/showthread.php?t=2681059


then space up you passenger mount to match, once you do that your bellows will likely stop rubbing.


Frank, he had to use all new parts, that's the rack to get if you are paying full price.

[Speedy G]

Mmmm... I thought I'd read and understood the whole thread. I hadn't seen that spacer. Sounds like an easy enough fix and even easier test (with washers). That means longer bolts... find, buy, wait, install...

Well, the choice regarding the 2015 sti rack is a bit of both. This rack was cheaper than new older ones and also I was looking for the better ratio. If the fix is as easy as 3 spacers, then we're golden.

Thanks!

Speedy G

[Frank818]

Yeah that new part rule in Colombia I remember, I thought "new" meant "unused parts from the dealer, no matter the year", but maybe it means "this year new part".

[Speedy G]

Nah, I could've used a 2006 for small parts like the rack, but this one was cheaper. I only need a new unused engine, tranny, and chassis with a bill of sale. Everything else just needs to look new.

Speedy G

[Frank818]

Speedy, almost 4months, were are you at?

[Speedy G]

Hey guys,

I thought I'd update something since I've been MIA for a while. I'm still working on the build, just 3-4 hours a week is all I can spare. Also, since I'm doing and all new parts build, the main time sink has been sourcing the parts. For example, I have the front suspension all set, except for the pinch bolts that hold the ball joints. I also have the steering all set, but I'm missing the pinch bolts for the steering column coupling. I'm also missing the front axles so I can't attach the brakes so I can run the lines. It's been a real pain that some online parts suppliers just cancel the order once they find out it's a non-US card, so I've had to order several parts multiple times. I'm also currently working on the rear brakes. Putting together those e-brakes is no simple task.

In any case, the design is essentially done. AC propulsion really makes it really easy to install their drive. They take care of the brake lights and the reverse lights. I'm thinking the 2 drives will go on top of the tranny, as far forward and as low as possible. Initially the gas pedal will go straight to the drive and the instruments will be connected directly to the drive, the way AC propulsion intended it.

More soon...

Speedy G

[Canadian818]

Glad to see your still working on it speedy. Keep at it!

[Frank818]

I know what you mean Speed! I was and still am having a hard time sourcing many many many different parts. A lot of new parts me too and I've got turned around a few times cuz the nice place with nice prices and nice stuff wasn't shipping outside USA. That's just 350 million people, but you can't do anything when they don't want. :(

[Speedy G]

I thought I'd looked at all the viable tranny options, but the following link is giving me second thoughts:

http://www.torquetrends.com/e-miata-project

The thing to note is that this is a single motor AC propulsion conversion with a 0-60 under 4s in a car weighing in at ~2200lbs or more. 2200 lbs or less is my goal. He's running a 2nd gen drive and motor, but the torque curve is identical to mine. There's 2 cool things about this miata conversion in particular. The first is that he's using a self-made 2:1 gearbox reduction, which he sells, and a miata rear end. What's awesome about this is that he still gets 135mph max speed. On mine, I'd get 125mph due to the difference in the drive, which is perfect, really. The second cool thing is the battery pack with 100 NMC batteries!!! Now that's not your dad's miata! Those NMC cells alone problably cost like USD50,000!!! All-in-all I'm thinking that might be the most expensive miata ever, probably close to $100,000!! John Rubicon, if you're still watching, this guy sells these for trucks as well. He's also building a transaxle but says he's more than 12 months away. Maybe for Bob's 3rd build...

So, I'm thinking why not just couple the miata diff to his 2:1 gearbox... There's plenty of miata diff ratios and aftermarket lsds... One advantage is that I'd be able to really use the 12,000 rpm without worrying that the tranny's about to explode. If or when I add the second motor, the system could still work reliably since the gear reducer is capable of 800ft lbs. I could then change the miata ring gear and pinion to a lower ratio (higher gear) and gain more top speed. What to do...

Does anybody here know the distance between the miata differential input shaft tip to the axle centers? Can i mount the differential upside down? Those are the only 2 relevant questions to see if it fits. Cost is about the same since miata diferentials are probably available here, second hand.

Speedy G

[Frank818]

Electric really is a different world, a 10" 36lbs gearbox! :)



Does anybody here know the distance between the miata differential input shaft tip to the axle centers? Can i mount the differential upside down?

I'd guess Andrew and Tamra would have answers to that.

[Speedy G]

So what's a tranny good for if you can do 12,000 RPM? I did a simulation of a ferrari 458 vs an M4, vs 3 818s. The first 818 has a subie tranny with a 3.90 final ratio and shifts at 10,000 RPM, the second has a 2:1 reducer instead of the subie tranny and a miata 3.6:1 rear end. The last one has the subie tranny but shifts at 6,000 RPM. Shifting is simulated at 80ms, like the M4 tranny. My car will probably weigh around 1100kg so that's the number I used. What's interesting is that the fixed gear 818 doing 0-100kph is slower than the ferrari but faster than the M4, but is just as fast as the ferrari at getting to around 120kph and just as fast as the M4 at getting to 160kph. In other words it's geared for the the autobahn. So what tranny should I go with? Here it is:

59320

[Frank818]

Looks like you need to buy a Ferrari. lolll
Aside from that, the MT5 10k seems to have a very nice compromise along the line. Why can't you shift at 12k?

[Martin]

I'd always go for the ratio that gives me the best bang for the sort of driving you intend doing. i.e. If you are going on the autobahn a lot, go for that ratio. If you are going to be driving on regular motorways and will top out at 70mph most of the time, go for a gear ratio that gives you the best cruising experience, and so on.

I went for a gear ratio that gives me the most fun between 30-70mph under acceleration. I will rarely get a chance to put my foot to the floor and hold it there.

[Speedy G]

I actually didn't compromise. I used the motor's dyno, did a torque chart where I have gear and rpm as the axis and torque as the value. I shift when the torque value of the lower gear equals the torque value of the higher gear. It just so happens that with the stock mt-5 the shift point is around 10krpm. Maybe with a diesel gearbox I can get to 12,000 rpm but I think acceleration would be worse. I do have to say that this is conservative, since I put in an 80% efficiency multiplier for the torque value with the mt-5 and 90% efficiency with the 2:1 reducer. Also, the guy that makes the 2:1 reducer has an electric Miata with the same motor as I do. He says he gets 0-60 in under 4s, which is what I'm getting, but I have twice the horsepower than he does, so who knows. Then again, anything under 4s is fast and traction is an issue. Honestly, here my average speed is 9mph due to traffic, at least that's what my beamer's computer says, so it'll be more efficient to be able to choose gears, even if you can only shift when the car is stopped (remember no clutch?). Here's my shifting table:

59332

[Frank818]

9mph average speed in your neighbourhood? Damn you need the shortest gears in the world to reach 5th at 6-7krpm and 9mph! lolll I run faster than that. Now we know you're not on the Autobahn. :(

Your torque figures are awesome.

[Frank818]

Updates?

[Speedy G]

Back to work next week... I'm done with brakes, alu panels, steering, and suspension. I'll be working on electrical next, and will start body fibreglass fitting simultaneously. I'll be doing the drivetrain last. It looks like my fellow ev builders are finishing up... that's actually motivating. Back soon..

[Speedy G]

Hey guys, slow progress, but the again, I have 3 year old twins.

I have a few different projects going on simultaneously, but the good news is I got a tranny with 1000 miles on it for 1100 bucks. For some reason, Subaru used to sell the hatchback imprezas locally pre-2008 with low range and in 2008 some customers had expected the low range and they stopped importing them with it. Some customers demanded subaru to provide a low range for their cars, and subaru abliged. They changed the trannies for around 10 customers, and that means they have like 10 5mt trannies with no low range lying around with nobody interested in them, except for me. The bad news? They're meant for 1.5L 110hp engines. The good news? They have a 4.44 final drive. Since I only need 2nd gear initially, this is my best case scenario. These trannies aren't available in the US since the smallest engine available there is a 2.0L. Here's a pic of the tranny:

66004

Speedy G

[Frank818]

I have 3 year old twins.

You're in trouble, man. lolll
I mean build-wise.

What's a tranny with low range?
You can't drive more than 50km before it breaks?

Which Subaru uses 1.5L? (I know it's not available in North America)

Will you use 4 gears out of 5?

That's a tiny gearbox!!! They fitted 5 gears into that?
How much torque can it support? On electric power are you sure you won't bust it?

[Speedy G]

Low range is like on a jeep. Usually it's like an additional 2:1 final drive on the output shaft so first gear will have a torque multiple of 28:1 instead of 14:1. Subaru however has a low range on the input shaft. It only multiplies by 1:1.196. That means the tranny has to take the extra torque that the low range multiplies. It's available on Australian N/A Foresters and hatchback imprezas. Actually Euro, Australian and South American imprezas can come with 1.5L engines, or at least they did in2008.

The thing about subaru is that it's all like a lego set. The tranny is the same on N/A imprezas, N/A foresters, etc with engjnes from 1.5-2.5L. The tranny itself is almost exactly in every way to the wrx tranny. The only visible differences are the clutch fork and the stub axles. The ratios are also different as is the final drive. The final drive seems to hold a lot of power, at least that's what the dune buggy crowd says. Some say the gears may not be as strong so there's probably some additional strength from heat treatment or a different alloys since dimensionally they're the same. We'll see, but for the first stage I only need it to hold 150ftlbs at 8,000 rpm, and I only need 2nd gear. Teslas only drive in 2nd gear. Later I'll be buying a PPG 3rd and 4th gear dog set to get a higher top speed. What I do need is an LSD. The factory helical one should be ok but it's expensive. I'm still looking for alternatives.

Speedy G

[Frank818]

150lbs at 8k? I thought electric motors have their max torque at 0rpm?

[Speedy G]

150ftlbs between 0 and 8000rpm. Horizontal line. Max hp is at 8000RPM. It's really not that much torque, but since it's constant to that high an RPM, horsepower is higher numerically than torque. Ideal shifting is at around 10kRPM.

[Frank818]

Is this going to be faster than if you had a WRX engine?

[Speedy G]

0-60 on par with you, probably low 3s, upper 2s. Top speed will suck initially, so yes but no.

[Frank818]

That's very powerful for 150lbs!!

[Speedy G]

Hey I'm not making it up, although I may have fudged the numbers a tiny bit. The original ac propulsion t-zero did it in 4.07 (3.6 with 1 motor and lithium cells). They claimed 336v nominal which is what I'm going for, and their car weighed 2290lbs (1800lbs with lithium cells). I'm still not sure what mine will weigh, but definitely less than 2290lbs. My motors are the same as what they used. With 2 motors the main issue wilk be traction but 11's in the quarter should be doable without shifting, better if I can shift into 3rd and 4th. Hey, after all my motors are the reason why Elon Musk replaced the engine in his 911. It might not be 150ftlbs, more like 177ft lbs, but still... that's les than your original VR6 torque.

https://en.m.wikipedia.org/wiki/AC_Propulsion_tzero

Speedy G

[Frank818]

And 3 years later... loll What's new?? :)