Electric 818 possibility

[KrissMotors]

As both a FFR builder (2009 Mk3 Roadster) and electric converter (1957 Porsche 356 Speedster and 1967 Saab Sonett V4), I've been interested in the 818 since it was first announced that the rear engine Subaru Impreza would be the donor platform. Electric conversions are easier with either front or rear engine/transaxle combos.

Until this past month, there was no suitable alternating current motor with enough power (and reasonable price) for the 818. However, a small company in California has just begun shipping a larger version of a motor I've used very successfully in two prior conversions. The chart below shows how this motor - the AC-75 - compares to Subaru engines; I've previously used the AC-50.

15792

As you can see, the AC-75 is quite powerful and matches even the turbo WRX engine torque. In addition, electric motors have a flat initial torque curve at the maximum value, which provides outstanding acceleration (much better than gas engines of comparable power). Thus, an AC-75 powered 818 has a tremendous performance potential. The AC-75 weighs about 180 lbs. The AC-75 could be powered with a 38-cell LiFePO4 lithium battery pack that outputs about 125v at 650 amps. This battery pack weighs about 290 lbs, so the total weight of the electric powerplant would be around 480 lbs (with motor controller, etc.). There is the potential to distribute weight with low center of gravity and excellent balance.

An electric 818 would eliminate the gas engine, fuel tank, radiator, 12v battery, alternator, and other systems relating to ICE. The AC-75 would mate to the same Impreza WRX transmission (5-speed manual, TY754 series). This raises the possibility of a cost-effective non-donor electric 818 build since you don't need the engine at all.

My ballpark figures suggest that a complete 818 EV would be assembled for about $30k (assuming a $10k FFR kit cost). This $30k would be for all new parts, non-donor. A donor/pallet path would be less of course.

I hope there are others here on this forum who might be interested in exploring this electric option.
SEE ALSO THIS RELATED THREAD (http://thefactoryfiveforum.com/showthread.php?9322-Electric-818-AC-amp-LiFePO4-configuration) that specifically covers lithium LiFePO4 | AC configurations.

[papajon1000]

any Idea on the range(city/ highway or combined) of a setup like this?

Thanks

[longislandwrx]

http://thefactoryfiveforum.com/showthread.php?2058-Question-Any-interest-in-bolt-in-Pre-engineered-Electric-Drive-Lines-for-FFR-Kits&highlight=electric+powered

[KrissMotors]

any Idea on the range(city/ highway or combined) of a setup like this?

Thanks

The battery pack I describe above is 100 Ah capacity and would probably have a 80-100 mile range assuming close to a 1800 lb curb weight. My Porsche Speedster EV has a 200 Ah capacity pack with range over 150 miles, but this adds weight of course. The exact battery capacity would depend on space, weight, and some other variables.

Clearly, limited range is one of the trade-offs of an EV at this point in technical development. Charging could be regular household current, or fast charging is also a evolving option, but not widely available right now. Cost BTW is around $0.015 per mile, or about $1.50 per full charge.

[Mechie3]

Why source parts separately? I bought my 06 donor for $4k, sold $2k in parts, and still have the motor and trans. Trans can sell for $1k easily, $1400 if you can wait. Motor will bring $2k at least. That means you can source all of your donor parts for free!

What's the cost of the motor/drives themselves?

[KrissMotors]

Why source parts separately? I bought my 06 donor for $4k, sold $2k in parts, and still have the motor and trans. Trans can sell for $1k easily, $1400 if you can wait. Motor will bring $2k at least. That means you can source all of your donor parts for free!

What's the cost of the motor/drives themselves?

A donor route is certainly feasible and I'm not suggesting otherwise - simply that a non-donor is also possible given that the engine and all related systems are no longer needed. You do need the Subaru transmission.

Other electric-specific components would be:

battery pack $6000 - assumes 38 cells, 100 Ah capacity, LiFePO4 chemistry, 3.4v nominal, wired in series
motor/controller $5000
charger/other components $1000

[MPTech]

Sounds like a cool idea. I'd like to see how this build goes.

Just curious (and I know this would be hypothetical), but how would this e818 compare to the Tesla roadster? (range and performance-wise) Weren't they selling for close to $100k?

[Oppenheimer]

There are so many donor parts used besides just the engine and trans that I think it would still make sense to use whatever donor path you would otherwise have used (if electric 818 were not an option), and simply not use the engine (sell it, etc).

[longislandwrx]

Cool Idea, although that range is just painful for the money spent. My 818 will remain dinosaur powered.

[KrissMotors]

Sounds like a cool idea. I'd like to see how this build goes.

Just curious (and I know this would be hypothetical), but how would this e818 compare to the Tesla roadster? (range and performance-wise) Weren't they selling for close to $100k?

The Tesla Roadster (https://en.wikipedia.org/wiki/Tesla_Roadster), now out of production, had several models with different motor torque and battery packs. The largest "sport" pack had a theoretical range of around 250 miles with vehicle cost well over $160k. The base model was around $125k and a 100-125 mile effective range (but range is very controversial ... Tesla claims a higher number).

The max torque of the Roadster Sport 2.5 was 295 ft-lbs pushing a 2800 lb frame, or 0.11 torque/lb, a good proxy for acceleration. A theoretical 818 electric with the AC-75 described above would have max torque of 238 pushing a 1800 lb frame, or 0.13 torque/lb (higher number is better). I'd say that the 818 would beat the Tesla, both on the 1/4 mile and certainly on cost! It would also beat, I'm pretty sure, any gas-powered version of the 818.

But penalty is range. Range will never be as good as a gas-powered car until new battery chemistry evolves. BTW the LiFePO4 lithium chemistry I reference above is not the same lithium chemistry that Tesla uses.

[papajon1000]

Thanks for the response about the range.


I'd say that the 818 would beat the Tesla, both on the 1/4 mile and certainly on cost! It would also beat, I'm pretty sure, any gas-powered version of the 818.



^ This however is a pretty bold statement.

[KrissMotors]

This however is a pretty bold statement.

Well, this really comes down to torque and curb weight. If you can get a maximum amount of torque to the rear wheels for a given curb weight, this will result in the fastest acceleration, all others things (like the driver) being equal. The torque curve of an AC-75 electric motor is FLAT between 0 and 2000 rpm at the maximum torque level. No internal combustion can match that. If you can shift fast enough, it seems - at least on paper - that an electric 818 would beat a gas-powered version.

[David Hodgkins]

If you guys have ever seen an electric vehicle accelerate the statement wouldn't seem so bold. Electric motors have insane amonts of torque!

This is a really interesting idea, and something to consider, definitely. I considered going electric with my roadster but couldn't gather research to support it.

An electric 818 seems more doable. I hope to see someone come up with a viable plan for this in the near future.

:)

[flytosail]

If you guys have ever seen an electric vehicle accelerate the statement wouldn't seem so bold. Electric motors have insane amonts of torque!

This is a really interesting idea, and something to consider, definitely. I considered going electric with my roadster but couldn't gather research to support it.


An electric 818 seems more doable. I hope to see someone come up with a viable plan for this in the near future.

:)

Tesla Model S from Motor Trend is 4.0 seconds for 0-60 and quarter mile time of 112.5. Bold enough?

[KrissMotors]

The world of electric motors is quite different in many respects to what we are all used to with gasoline engines. The torque profile is one profound difference. The first chart is for the AC-75 operating at 96 volts and 650 amps.

15801

Note that torque is flat up to about 2000 rpm. In practice, this means that electrics have nearly "instant" torque ... you don't rev up the motor first, you just go. Higher volts will boost torque, and the proposed system discussed here is about 125v, not 96v.

In contrast, the second chart is the torque curve (heavy line) for a 2000 Subaru Impreza (not exactly the same as a EJ255 turbo on the WRX, but the concept is the same). Note that engine torque isn't even useful until over 2000 rpm. Max torque isn't reached until over 5000 rpm, and it is available only for a very short range of rpm.

15802

This explains why electrics will always beat gas-powered vehicles if they have similar power and other handling characteristics.

[KrissMotors]

Here is an example (http://krissmotors.com/blogs/post/Sonett-Electric-front-motor-bay/) of an electric motor bay - conversion of a 1969 Saab Sonett which is a front-wheel motor/transaxle configuration. The AC-75 discussed in this thread is slightly larger than the AC-50 shown in the photo.

[longislandwrx]

Note that engine torque isn't even useful until over 2000 rpm. Max torque isn't reached until over 5000 rpm, and it is available only for a very short range of rpm.

15802

This explains why electrics will always beat gas-powered vehicles if they have similar power and other handling characteristics.

And on the 8th day God created launch control.

[Mechie3]

If it wasn't so expensive it'd be fun to build two! One gas one electric.

I do much prefer electric go karts over gas.

[MPTech]

I'd like to build one of these to offset the carbon footprint of my roadster! (and laff at my neighbor's old Prius! man I hate those things! FUGLY! but I LIKE the electric cars)

The 818 seems like a really good platform for this project. I've seen some of the youtube videos of the electric drag cars. UNREAL torque! Getting it to hookup would be the trick.

What do you figure the weight of the completed e818 vs. the gas version? (maybe I missed it in the post)

Good luck with this project. Sounds VERY cool!

[Xusia]

I'd really prefer electric, but the price just isn't there yet. I'm hoping that by the time my EJxx engine needs a rebuild, that going electric will be cost effective. My personal preference is in-wheel motors, a smallish battery pack (~50 miles), and an on-board electric generator (preferably gas or diesel so I can take trips if I want).

[KrissMotors]

What do you figure the weight of the completed e818 vs. the gas version? (maybe I missed it in the post)

The electric motor/battery pack/controller/charger/wires/etc will weigh about 500 lbs. but you delete the engine/gas tank/radiator&cooling/alternator/exhaust/fuel system/engine electrical/etc. Perhaps a Subaru expect on the forum can estimate what the weight is of the deleted components so we can get a rough idea about the net change in gross curb weight.

Related issues are vertical center-of-gravity and horizontal weight balance. Because the battery pack is comprised of 38 individual cells, each about the size of a NYC phonebook, you can distribute them through the vehicle to achieve a 50/50 or other balance. Also, it appears that a large group of cells can be placed behind the seats where the gas tank is (?? I have not seen the 818 yet, only photos and drawings) which seems like an excellent spot to add weight in front of the rear axle for traction. Batteries placed in this location will probably weight more than a full tank of gas. For racing applications, you could even place batteries on the passenger side to compensate for the weight of the driver, but I don't plan to do this for a street version (the version I'm considering).

Finally, vertical center-of-gravity has a significant impact on handling characteristics. The electric motor and battery pack is generally mounted lower than the engine mass centerline, so center-of-gravity is reduced (a good thing). In my electric Porsche 356 Speedster, the balance is 50/50 and COG is lower than the original ICE car. As it result, it handles much better in autocross, doesn't fishtail like the original, and generally improves the period-correct swing axle performance, all in a vehicle that is only about 150 lbs heavier than the OEM original. I am hopeful that clever engineering will allow for a weight improvement (balance, center-of-gravity, and perhaps overall curb weight) of the electric vs ICE 818, but much detail lies ahead.

[papajon1000]

Tesla Model S from Motor Trend is 4.0 seconds for 0-60 and quarter mile time of 112.5. Bold enough?

Just so we are clear, I am not downplaying/hating a well engineered electric vehicle. KrissMotors just stated that an electric powerd 818 would beat ANY gas powered 818.

To me it always comes back to money. For the price of getting a tesla... well you know where I am going with this.

Again thank you KrissMotors for all of your info.

[KrissMotors]

Here is a photo of a LiFePO4 (lithium iron phosphate) battery cell, 100Ah size.
15804

An electric 818 would carry 38 of these in series. Manufactured in China by CALB. Weight is about 7.5 lbs each. Current cost is $150/cell and add about 10% for local delivery.

[RM1SepEx]

so for 60 +/_ range
38 x 150 for batteries $6000
double range double the battery cost $12000 for batteries
AC-50 with controller 650 amp max $4500
Large wiring, contactor, fuse etc $1000
BMS $500??
Charger $600 (low end)
Gauges, low voltage wiring controls etc... $1000
Kit $ 10,000
Other donor parts $2500 ??? good donor paert out un-needed parts yada yada yada

for 60-70 miles maybe with 100AH @ 120 volts

6 + 4.5 + 1 + .5 + .6 + 1 + 10 + 2.5 = $26,000 +10% misc add-ons $29,000

double the range add 6K = $32,000 + 10% =$35,500

I'm very interested in the expected watts/mile using such a setup as my theory is to provide gen-set capacity for cruising load only... software turns the generator on and off based on battery capacity and expected load based on GPS data.

I've considered a second 818 with a serial, on board gen set... I'd shoot for only 40 - 50 miles of battery only range but it would differ for each user.

[KrissMotors]

... BMS $500??


Just to clarify: these LiFePO4 do not need a battery management system (BMS). In fact, a BMS is downright dangerous! You do need battery measurement - voltage, amps, battery capacity - so I'm not sure what you mean by "BMS". A very good measurement system is now under $200.



... AC-50 with controller 650 amp max $4500


The AC-50 would also work very well in the 818 given its low curb weight instead of the AC-75 I discuss above.

[RM1SepEx]

Like you I have built an electric vehicle, in my case an electric reverse trike. I bought my components from thunderstruck motors in CA. They have extensive experience with all battery technologies. They indicate that a BMS is required for these LiFePO4 batteries for best service life

most lithium cell mfg rec bms systems to avoid charging inequalities... I have seen a few companies that do not use them however.

http://www.thunderstruck-ev.com/battery-management-system.html
http://www.batteryspace.com/lfp-bms-starter-kit-for-12-8v-lifepo4-prismatic-battery-pack-4-cells-with-lcd-screen-display.aspx
http://www.cleanpowerauto.com/MiniBMS.html
http://www.all-battery.com/protectivepcbsforlifepo4.aspx
http://www.evsource.com/tls_lithium_calb.php

every source that I found for the CALB batteries also sells a BMS for them... so IMHO one is required based on the research that I've done.

BTW nice generic range battery pack calculator here: http://www.evsource.com/battery_calculator.php

[MPTech]

Ran across this on another site and thought it may be of interest. Looks like a different approach.

Factory Five Project 818 4wd EV (http://www.diyelectriccar.com/forums/showthread.php/factory-five-project-818-4wd-ev-76736.html)

[timmy318]

How would you make this car have AWD (Rear gas & front electric powered).

[RM1SepEx]

you can see info in the previous posting from the other forum. I would think it would be easy to add a set of smaller wheel based electric motors vs a motor between the wheels in the center of the chassis. Also the netgain warp 9 is HUGE significant benefit could be obtained with a smaller motor if you went this route. The chassis and front shock setup would need to be reworked. I think you could get quite a boost in performance with smaller wheel based motors, regen braking and smaller capacity batteries, perhaps a row up the center of the chassis or a couple stacks outboard in the rocker panel areas.

http://www.foxnews.com/leisure/2012/07/18/protean-electric-looks-to-revolutionize-electric-cars-with-in-wheel-motors/

http://phys.org/news/2012-07-wheel-hub-motor-concept-hybrid.html

[Xusia]

Ran across this on another site and thought it may be of interest. Looks like a different approach.

Factory Five Project 818 4wd EV (http://www.diyelectriccar.com/forums/showthread.php/factory-five-project-818-4wd-ev-76736.html)

I had this thought as well. I think it could be easily done. You could potentially even re-use the rear differential from the donor (obviously requiring some work on the axle side of things). It would just cut into the trunk space.

But as RM1SepEx said, wheel motors make the most sense. Although at that point, I think putting them in the rear wheels is better, in order to retain the front brakes (and therefore superior stopping ability).

[veloce2]

But is the 818 a drag car? lets face it the Ariel Atom has already done this and it will be faster, due to less weight, so that leaves you with a track option which sucks because the battery weight is huge.

[Xusia]

To each their own. The Atom is awesome, but unlike the 818 the Atom lacks the ability to be a daily driver in Oregon (where I live). Point is everyone has their preferences and priorities...

[Matty_STi]

This probably won't be the best idea with the 5MT "glass" transmissions.. It's not necessarily torque that kills transmissions but shock loads. Shock loads can be seen as a torque vs vehicle speed vs acceleration. electric motors have essentially a flat torque curve and thus can produce insane shock loads for not just a short duration but a duration far beyond what a standard small displacement turbo motor (lets ignore rally cars and anti lag for a moment).. EV's are cool, but to use a stock 5mt would be frankly stupid, you would have to baby it to keep from shredding gears until further in the rpm band/vehicle speed range... I wouldn't do an ev car with a 5mt without swapping to ppg or albins or modena or kaps gears, or an sti trans (probably would consider upgrading the gears in the sti too). also will have to get a better clutch that can handle far higher torque loads due to the instantaneous nature of the torque and the fact that a drop in boost or rpm won't pull down torque values... (and people wigged about the potential costs of my build..... :S )

-Matt

Just sayin...

[Xusia]

(and people wigged about the potential costs of my build..... :S )

LOL

The transmission is a potential issue for sure. One of the many reasons why I think wheel motors make more sense. One thing to note, though, is that you don't really need a clutch at all. One of the nice things about electric motors is that unlike gas engines, the power can be cut for fractions of second, and because there is very little actual rotating mass (compared to an ICE), the motor can slow down very quickly allowing the gears to mesh. You can actually do the same thing with gas engines (depending on the design), it's just a lot easier with a motor.

[veloce2]

True to each their own I was just pointing out what has been done.

Battery power is interesting but the whole issue with batteries is a huge problem, not only for the cars handling, but distance. So how good are modern batteries? In 1906 there was a car company called Baker. The Baker could go 30-45 miles about the same distance as modern EV's, so what has really changed?

[Xusia]

I don't agree handling is an issue. If anything, an electric vehicle has several advantages:

Batteries are typically in packs, so there is more freedom in placement when compared to a gas engine (i.e. you can place them lower, you can better centralize the mass, you can even place some up front - or not! - to achieve the weight distribution you want, etc.)
Motors can be controlled to a much higher degree of precision than a gas engine, increasing traction (especially true if using traction control software)
If wheel motors are used, they can be controlled independently to achieve whatever oversteer/understeer characteristics are desired
As has already been stated, motors have a near flat torque curve, allowing for maximum power at nearly any moment/RPM


That said, the trade off is in range and/or potentially weight, as well as up front cost (meaning, electric costs more up front).

[Matty_STi]

Rev matching is going to be a pain and take a considerable amount of time to work out. With syncros you can fudge it a bit and be okay. But if you are worried about shredding gears and go to a dog box well now you have to be exact with rev matching as a dog box can only shift with slip and an absence of torque otherwise you will shred the dog teeth and now you've destroyed a 10-20 thousand dollar tranny... Oh and how will you sync the management system up with the trans to know when to cut torque (as throttle lift won't work so some other sensor will need to be employed) to allow that shift? That means custom designed sensors as I doubt anyone would want to pay for off the shelf parts already made for this sort of thing (I can only assume the costs of those), then design the electronics to allow proper signal conversion. blergh. Also torque has to be cut for a specific time frame and have some way of knowing if a gear isn't fully engaged before torque is reapplied otherwise again you'll be shredding syncros or dog teeth (again can't use throttle as a foot slip equals destruction), both of which are an expensive proposition...

I agree about wheel motors. Probably the better alternative... Haven't done an EV myself but worked with a tonne of electric motors so I can only make an educated guess.


LOL

The transmission is a potential issue for sure. One of the many reasons why I think wheel motors make more sense. One thing to note, though, is that you don't really need a clutch at all. One of the nice things about electric motors is that unlike gas engines, the power can be cut for fractions of second, and because there is very little actual rotating mass (compared to an ICE), the motor can slow down very quickly allowing the gears to mesh. You can actually do the same thing with gas engines (depending on the design), it's just a lot easier with a motor.

[Matty_STi]

+1 being able to position a high density material that also was the fuel AND didn't change weight massively as said fuel was consumed or move around like liquid fuels is an absolute boon to handling.. It's insane to think that an ev car would handle worse than it's gasoline counterpart as the EV has a defined mass that won't change. Talk to a racing driver and they will tell you how challenging it is to deal with the variations in weight as their cars use fuel and what that does to the tires, brakes suspension, and aero (yes aero because the ride height now changes as the car looses weight and there will be a change in aero). I know in my experiences (and I am not a professional driver by any stretch but I do have motorsports experience in a variety of fields and you can tell the differences as the car uses fuel and when you get fuel slosh.

Also with a dense material putting that in a spot for optimal weight distribution would be optimal.

As for the range and efficiency of batteries, there was a dark ages of battery research as the focuses on energy storage were super capacitors for large high energy weapons systems or physics experiments (NIF), nuclear batteries for space probes (the heat of radioactive decay from a radioactive isotope), chemical energy systems (more efficient use of a given chemical fuel) or micro fission or fusion reactors... Comparatively speaking battery research has only recently seen the big research investments (both monetarily and intellectually) as those other more exotic and interesting storage applications (or in the case of chemical fuels pure market size)..


I don't agree handling is an issue. If anything, an electric vehicle has several advantages:

Batteries are typically in packs, so there is more freedom in placement when compared to a gas engine (i.e. you can place them lower, you can better centralize the mass, you can even place some up front - or not! - to achieve the weight distribution you want, etc.)
Motors can be controlled to a much higher degree of precision than a gas engine, increasing traction (especially true if using traction control software)
If wheel motors are used, they can be controlled independently to achieve whatever oversteer/understeer characteristics are desired
As has already been stated, motors have a near flat torque curve, allowing for maximum power at nearly any moment/RPM


That said, the trade off is in range and/or potentially weight, as well as up front cost (meaning, electric costs more up front).

[Xusia]

Rev matching is going to be a pain and take a considerable amount of time to work out. With syncros you can fudge it a bit and be okay. But if you are worried about shredding gears and go to a dog box well now you have to be exact with rev matching as a dog box can only shift with slip and an absence of torque otherwise you will shred the dog teeth and now you've destroyed a 10-20 thousand dollar tranny... Oh and how will you sync the management system up with the trans to know when to cut torque (as throttle lift won't work so some other sensor will need to be employed) to allow that shift? That means custom designed sensors as I doubt anyone would want to pay for off the shelf parts already made for this sort of thing (I can only assume the costs of those), then design the electronics to allow proper signal conversion. blergh. Also torque has to be cut for a specific time frame and have some way of knowing if a gear isn't fully engaged before torque is reapplied otherwise again you'll be shredding syncros or dog teeth (again can't use throttle as a foot slip equals destruction), both of which are an expensive proposition...

I agree about wheel motors. Probably the better alternative... Haven't done an EV myself but worked with a tonne of electric motors so I can only make an educated guess.

I was speaking specifically about the clutch, and NOT about the transmission. I stated the transmission is an issue. You can effectively eliminate the clutch using a system like I describe, but the assumption for such is that the transmission can handle the power. Sorry I wasn't specific about that.

In regards to how a clutchless system works, you are way over thinking it. Most modern liter-sized sport bikes either have such a system standard or offer it as an option. It's really rather simple, and in most cases involves nothing more than a momentary ignition cut (though in the case of a motor, I would imagine it would need to be coupled with a more controlled re-application of power). Contrary to popular belief, you can do this both shifting up and shifting down (I've done it "manually" for years in both cars and motorcycles and have yet to expereince any damage as a result).

I'm not suggesting this is THE route to go, only that if you believe the clutch is an issue, there are other viable options. :)

[Matty_STi]

You can speak about just the clutch all you want to but this is still a unified system, you are now changing that and thus other adjustments need to be made to reflect that. This isn't something that can be thought of in a vacuum lots of these pieces need to be thought about as a unified whole.

I do know how clutchless systems work but there is a big difference between a liter sport bike revving to 15K and an electric motor that puts out 240 ft-lbs at 1 rpm. Back to my point about the vacuum unless you swap to a different transmission you are stuck with the 5mt and the problems inherent in that. In which case straight cut dog gears are what you should be looking at to handle the torque AND shock loads. (note a 240 ft-lbs e-motor in an 1800lb car will produce shock loads beyond what any designer of clutchless systems for motorcycles would dream of). There really isn't a good comparison here when looking at motorcycles. Your best bet as an accurate comparison would what top tear rally cars face for shock loads (especially the prodrive rocket anti-lag setups from the subaru wrc cars). What you will find is that in order to shift with out destroying their gear boxes there needs to be a perfectly timed dance between torque release AND tire slip (to unload the transmission from the grip produced by the tires) such that you can move the shift fork and engage the dog teeth at the exact rpm needed. The engine management systems for those transmissions are incredibly complex and time consuming to setup.

I will add i've talked to a few of the big vendors of gear boxes (kaps, modena, ppg) and those that are using them in serious motorsports endeavors. And what I have been told numerous times is shock loads are the killer and a dog box though it can handle greater shock loads will still be shredded when enough is applied to them.. And here's this for a mind blowing fact, a few vendors have told me about the torque numbers their transmissions are taking from drag racers for entire seasons without incident and are totally fine (upwards of 850 ft-lbs) and well beyond their "rating", and it's the rally teams that are destroying them (confirmed talking to guys running these transmissions in drag cars and rally cars).

I know you are saying that you are referencing a clutchless system with a transmission designed to handle the forces a motor like this could create, but those kinds of transmissions really don't run dog boxes. And short of putting in a 30,000+ dollar racing sequential setup you won't be able to easily create a dogbox setup that will work. If you have never driven a dogbox you won't know what I am talking about, ask any vendor how important proper shift technique is with a dog box and they will spend as much time as they can explaining it (and ask them how long a dog system will last with crappy shifting, - not very long). Syncro-trans would be easier as you don't need that precision of rev matching plus torque offloading (on both ends of the transmission, also wonder why in the upper echelons of motor sports they DON'T run clutchless transmissions but DUAL clutch ones? to cut torque acting on both ends of the transmission for not only faster changes but also reliability). However you won't find one that could handle those torque loads and shock loads in the WRX 5mt package.
http://www.ppgearbox.com.au/page.asp?productid=82 -> great setup but they are suggesting 400 hp as the load rating (which means similar or less torque figures at way higher rpm and also lower shock loads)
http://www.ppgearbox.com.au/page.asp?productid=1 -> this is what you would be looking at and don't be surprised if you're in the 10,000+ dollar range after installation.

e-car =/= high revving lightweight low torque bike -> the comparison just isn't a valid one

I think we are arguing the same point - there is a better way to do this. Though just via different means :) I am also not saying your idea of the clutchless system can't be done, I just don't believe based on my experiences, research and talking to those running big torque subie motors in race applications that you can go about this in a way that isn't hugely expensive and generally overly complicated and time consuming to setup and be reliable.. I am just focusing on the reliability side of things. Sure you could slap this all together with a stock trans and go but it won't be reliable. reliability is key here for my points to be taken in context.

If someone is going to run a single motor through the wrx stuff - personally (and this is just me) - i would do it through upgraded gearbox and clutch.

im with Xusia on motor/wheel design.

i love me a good technical debate!! :)


I was speaking specifically about the clutch, and NOT about the transmission. I stated the transmission is an issue. You can effectively eliminate the clutch using a system like I describe, but the assumption for such is that the transmission can handle the power. Sorry I wasn't specific about that.

In regards to how a clutchless system works, you are way over thinking it. Most modern liter-sized sport bikes either have such a system standard or offer it as an option. It's really rather simple, and in most cases involves nothing more than a momentary ignition cut (though in the case of a motor, I would imagine it would need to be coupled with a more controlled re-application of power). Contrary to popular belief, you can do this both shifting up and shifting down (I've done it "manually" for years in both cars and motorcycles and have yet to expereince any damage as a result).

I'm not suggesting this is THE route to go, only that if you believe the clutch is an issue, there are other viable options. :)

[RM1SepEx]

Run high enough voltage and you can wind an AC electric high enough rpm to go with a single speed... just run a LSD rear diff
Telsa found that even a two speed transaxle would break, simplify, no shifting just couple the two together

The problem that always comes up is battery cost, you pay upfront with electric vs by the mile with IC engines
As per ACpropulsion.com
ex AC 75 at 250 volts 13000 rpm engine, 3.54 rear diff and 25 inch tire dia. = 86 mph

minimum battery for such a setup 100AH LiFePO4's at 3.2V nominal and $150 each 78 batteries $12,000 7.5 lbs each (600 lbs)

This motor's specs are found here:

http://www.acpropulsion.com/datasheet/ac75.pdf

[10 10 Flyin]

Is the AC 75 a brushless motor? I would think a dc motor with CVT transmission would be optimum for acceleration and battery life. Many not be very fun to drive . . . .

Maybe a transmission from a diesel car would be more suited for this application. They probably are designed for higher Torque and i would expect them to have wider gear ratios to take advantage of the broader Torque range and lower rpms. Maybe something from a Volkswagen turbo??

[KrissMotors]

As per ACpropulsion.com
ex AC 75 at 250 volts 13000 rpm engine, 3.54 rear diff and 25 inch tire dia. = 86 mph

This motor's specs are found here:
http://www.acpropulsion.com/datasheet/ac75.pdf

To avoid confusion on this thread, the AC75 motor linked to above is NOT THE SAME AC-75 motor that I describe in my prior posts. ACPropulsion emerged out of the shutdown of the original General Motors EV1 and continued with their high voltage (250v) design. The AC75 (the name similarity is very unfortunate) I refer to is a mid-voltage design (about 125v max) from a different company; see photo and dimensions below.

1582715828

[KrissMotors]

Is the AC 75 a brushless motor?


Yes, the AC-75 I refer to (see my prior post with photos and dimensions) is brushless. The "AC" refers to alternating current, and this type of motor does not use brushes.

[RM1SepEx]

this one?

http://www.thunderstruck-ev.com/ac-75.html

what kind of RPM will it turn at 125 volts

[wleehendrick]

The Atom is awesome, but unlike the 818 the Atom lacks the ability to be a daily driver in Oregon (where I live).

A little off-topic, but I travel to Wilsonville, OR (South of Portland) frequently for business and see an Atom in the parking lot; the only time I've ever seen one on the road in person. Daily driver? maybe for July/August!

[KrissMotors]

this one?

http://www.thunderstruck-ev.com/ac-75.html

what kind of RPM will it turn at 125 volts

Yes, this is the AC-75 I'm referring to. Don't understand your question about RPM and volts. See my post #15 for torque curve.

[Xusia]

You can speak about just the clutch all you want to but this is still a unified system, you are now changing that and thus other adjustments need to be made to reflect that. This isn't something that can be thought of in a vacuum lots of these pieces need to be thought about as a unified whole.

I do know how clutchless systems work but there is a big difference between a liter sport bike revving to 15K and an electric motor that puts out 240 ft-lbs at 1 rpm. Back to my point about the vacuum unless you swap to a different transmission you are stuck with the 5mt and the problems inherent in that. In which case straight cut dog gears are what you should be looking at to handle the torque AND shock loads. (note a 240 ft-lbs e-motor in an 1800lb car will produce shock loads beyond what any designer of clutchless systems for motorcycles would dream of). There really isn't a good comparison here when looking at motorcycles. Your best bet as an accurate comparison would what top tear rally cars face for shock loads (especially the prodrive rocket anti-lag setups from the subaru wrc cars). What you will find is that in order to shift with out destroying their gear boxes there needs to be a perfectly timed dance between torque release AND tire slip (to unload the transmission from the grip produced by the tires) such that you can move the shift fork and engage the dog teeth at the exact rpm needed. The engine management systems for those transmissions are incredibly complex and time consuming to setup.

I will add i've talked to a few of the big vendors of gear boxes (kaps, modena, ppg) and those that are using them in serious motorsports endeavors. And what I have been told numerous times is shock loads are the killer and a dog box though it can handle greater shock loads will still be shredded when enough is applied to them.. And here's this for a mind blowing fact, a few vendors have told me about the torque numbers their transmissions are taking from drag racers for entire seasons without incident and are totally fine (upwards of 850 ft-lbs) and well beyond their "rating", and it's the rally teams that are destroying them (confirmed talking to guys running these transmissions in drag cars and rally cars).

I know you are saying that you are referencing a clutchless system with a transmission designed to handle the forces a motor like this could create, but those kinds of transmissions really don't run dog boxes. And short of putting in a 30,000+ dollar racing sequential setup you won't be able to easily create a dogbox setup that will work. If you have never driven a dogbox you won't know what I am talking about, ask any vendor how important proper shift technique is with a dog box and they will spend as much time as they can explaining it (and ask them how long a dog system will last with crappy shifting, - not very long). Syncro-trans would be easier as you don't need that precision of rev matching plus torque offloading (on both ends of the transmission, also wonder why in the upper echelons of motor sports they DON'T run clutchless transmissions but DUAL clutch ones? to cut torque acting on both ends of the transmission for not only faster changes but also reliability). However you won't find one that could handle those torque loads and shock loads in the WRX 5mt package.
http://www.ppgearbox.com.au/page.asp?productid=82 -> great setup but they are suggesting 400 hp as the load rating (which means similar or less torque figures at way higher rpm and also lower shock loads)
http://www.ppgearbox.com.au/page.asp?productid=1 -> this is what you would be looking at and don't be surprised if you're in the 10,000+ dollar range after installation.

e-car =/= high revving lightweight low torque bike -> the comparison just isn't a valid one

I think we are arguing the same point - there is a better way to do this. Though just via different means :) I am also not saying your idea of the clutchless system can't be done, I just don't believe based on my experiences, research and talking to those running big torque subie motors in race applications that you can go about this in a way that isn't hugely expensive and generally overly complicated and time consuming to setup and be reliable.. I am just focusing on the reliability side of things. Sure you could slap this all together with a stock trans and go but it won't be reliable. reliability is key here for my points to be taken in context.

If someone is going to run a single motor through the wrx stuff - personally (and this is just me) - i would do it through upgraded gearbox and clutch.

im with Xusia on motor/wheel design.

i love me a good technical debate!! :)

I love a good technical debate as well (chuckle), though I think I just realized why you might not have been understanding what I was really trying to say. Clutchless shifting is the act of [a human] changing gears without a clutch. It is NOT the act of using some kind of device to perform the actual gear changes. That's called an automatic. :)

My single and only point remains: That systems exist to manage clutchless shifting.

I am not now, nor have I EVER been, in favor of mating a powerful motor with the 5mt - clutch or not! So if someone - NOT ME - were to go this route and had ALL THE OTHER DETAILS IRONED OUT such that the clutch was only weak point left, there exists an option that eliminates the need for a clutch. All these systems do is manage the power output of whatever is connected to the transmission input shaft (obviously, different control systems are required for engines vs. motors since their power output is controlled differently). A motor can be controlled more easily and with greater precision than an engine - I only bikes as an example of where such has been applied to gas engines lest anyone think such a system was for motors only.

Clutchless shifting systems don't care how much power the engine/motor makes, how many cylinders it has, the maximum RPM, the weight of the vehicle, it's current speed, or really any other details. It simply cuts the power slightly (there are several techniques to achieve this), and for just long enough, to allow a human to change the gear. Then the system releases the engine/motor to it's normal management. If someone were worried that re-application of power would occur too quickly (regardless of how much power that actually was), the system can be programmed to return to a normal engine management state more gradually. Heck, you could even hook said system to a "clutch" pedal and control it manually!! Again, power output, rpm, etc. is irrelevant to the functioning of these systems. Therefore, there are no inherent differences between systems that work on motorcycles vs. cars, as both are gas engines and managed the same way. There might be some programming differences based on the specific application, but so would there be between 2 different bikes or 2 different cars.

I hope what I was saying makes more sense now.

To clear up any other potential confusion regarding my thoughts/position on an electric 818:

I agree (for the third time now) that the 5mt transmission could have trouble with the torque output of a motor.
I believe wheel motors are probably the best option because they don't require transmissions, differentials, etc., and therefore get around a LOT of issues. Also, because they are connected directly to the wheel, they have the least amount of mechanical loss (just what's inherent in the motor).
The completed build cost for an electric 818 is UNLIKELY to come in at less than even a 2007 low mileage WRX build. I said early on, financially this was not an economical route. And more power/speed = more money, regardless of whether you are talking electric of gas.
Dual clutch is awesome. Since I'm not involved in Formula One, I can't speak to why they use one system over another. I can tell you that if the transmission with a single clutch can handle the power and the shifting, then there is no reason a clutchless system wouldn't also work. That said, we need to bear in mind those are extreme applications and therefore not representative of what is applicable for the vast majority of 818 builds.

[Gearsmith]

Other electric-specific components would be:

battery pack $6000 - assumes 38 cells, 100 Ah capacity, LiFePO4 chemistry, 3.4v nominal, wired in series
motor/controller $5000
charger/other components $1000


Thanks for posting this. An electric 818 would be incredible. Would you happen to know, or could estimate, the life of the $6,000 battery mentioned above? And also for the motor? Of course driving style (that is, how hard the car is driven) will influence this. But I'm just trying to get an idea when I'd have to pop for another $6K battery pack.:confused:

GS

[KrissMotors]

Thanks for posting this. An electric 818 would be incredible. Would you happen to know, or could estimate, the life of the $6,000 battery mentioned above? And also for the motor? Of course driving style (that is, how hard the car is driven) will influence this. But I'm just trying to get an idea when I'd have to pop for another $6K battery pack.:confused:

GS

BTW, I've started another thread (http://thefactoryfiveforum.com/showthread.php?9322-Electric-818-AC-amp-LiFePO4-configuration) to specifically discuss the LiFePO4 / AC motor configuration.

One huge advantage of the LiFePO4 chemistry, in contrast to other lithium ion batteries including those used by Tesla, is a very long cycle life. I estimate that the LiFePO4 battery packs I've installed will probably last at least 200,000 miles. In other words, they are essentially good for the useful life of the chassis itself. In terms of the AC motor, if not abused or overheated, they will last nearly forever without any maintenance. AC motors have no brushes, and only ONE moving part. There are industrial AC motors that have been in continuous operation for decades!!

But one word of caution: batteries can be damaged by either over-charging or over-discharging them; motors can be damaged if overheated. If treated properly, expect a very long life for both with no need to ever replace.

[Xusia]

Do you know of any viable wheel motors? Protean seems to be the forerunner from a technology standpoint, but they don't have a product for sale to the public yet.

[KrissMotors]

Do you know of any viable wheel motors? Protean seems to be the forerunner from a technology standpoint, but they don't have a product for sale to the public yet.

In theory, wheel motors hold tremendous conceptual promise. There have been several serious commercial attempts at car wheel motors, all - to my knowledge - ending in one sort or another of technical failure or cost infeasibility (or both). The primary problem is suspension vibration. The unsprung weight of a car wheel motor appears - given current suspension technology - too large to dampen enough to enable the rather delicate rotor to turn without damage or other side effects. Works in the lab, but fails under real world conditions.

Bikes/motorcycles offer a much more attractive weight/suspension profile, and are certainly penetrating this niche rather quickly. But IMHO car wheel motors are still at the bleeding edge stage and many years in the future (if at all).

But I should say I don't follow this closely, and I would defer to others with real working field knowledge about wheel motors which I don't have.

[Xusia]

Hmm. I thought they HAD overcome that issue, but perhaps not. One potential solution is to simply mount the motor inboard and use an axle. It still eliminates differentials, transmissions, etc. The problem is that it still requires a motor with a more pie shaped profile (i.e. wheel motor) than a cylindrical profile - I don't think you could fit 2 AC-75 motors between the two wheels. If you could, however, you would have further weight reductions.

[veloce2]

Yea thats why the Tesla was such a great track car??? They took one of the best, the lotus and they should have been able to make it better according to your desires. Sorry it just isn't true, if it was we would se electric cars racing all over the world against fossil fuels, but we don't. I have only seen EV's do well in a drag race.

If it's such a great idea ....bring it on............. were holding our breath.

[BipDBo]

A motorcycle from zero would conatian nearly all of the compenents to make an electric 818.
http://www.zeromotorcycles.com/zero-s/specs.php
The ZERO S ZF11.4 comes with a 54 hp motor and an 11.4 kw-hr battery pack. At $15,995, it's not a cheap donor, but perhaps they might be willing to sell the components without the full bike.
I think that a better application for this would be to make a plug-in hybrid 818. The rear wheels could be driven by aboxer. The front wheels could be driven by the motor. The zero controls include capability for regenerative braking.
The ZERO S ZF11.4 weighs 387 lbs. I don't know how much of that is bike (frame, wheels, etc.) I'd guess that the motor battery, controls, etc may add around 275# to an 818.
With that extra 275#, though, you would get the ability to cruise for around 40 miles without the engine on, an added 54 hp, and traction to all 4 wheels.
How to control it is a difficult question. Since the gas engine and gearbox in back would be mechanically separate from the EV drivetrain in front, I'd imagine EV controls separate from the gas an brake pedals. Perhaps an EV throttle an regenerative brake control mount to the stick shift somehow.

[Xusia]

The Zero has a TPS (Throttle Position Sensor). I would think it would be fairly easy to connect that to gas pedal. Some linkage may be needed to properly match the travel of the foot pedal to the range of the TPS.

[Dan Babb]

Just curious...If you just need standard household electric to charge up the batteries, then couldn't you figure out how to mount a portable generator in the front of the car and run that to recharge the batteries while you're driving?

Wouldn't that extend the range if needed?

Granted, you'd probably be limited in the size of the gas tank that could feed the generator.

[Xusia]

DING DING DING! To me, that's the best solution *IF* you need or want nearly unlimited range (like gas vehicles enjoy), and to spend less on batteries. I don't think it would necessarily weigh less, and you still have trade-offs. Specifically, generator size & weight vs. capacity. I would think you would need a generator at least large enough to provide enough current to drive the vehicle by itself at a lower highway speed. So how big is that? I have NO idea...

[RM1SepEx]

Yes, this is the AC-75 I'm referring to. Don't understand your question about RPM and volts. See my post #15 for torque curve.

thre is a direct relationship between rpm and voltage... apply more voltage, the motor spins faster. so if it's maximum voltage is 125 ac volts what does that result in for rpm. You need to know that to determine gear ratios, top speed etc...

to Xusia

Using "rounded" numbers

it takes 12 -13 hp to go 65 as a generic estimate (drag coeff, frontal area, rolling resistance)
1 hp is 746 watts
at 125 volts, that is 6 amps
so... 13 hp is 78 amps at 125 volts, you have a bunch of effeciencies that come into play, I'd assume 75% as a starting point so you would need 104 amps That would require an 18-20 hp generator

Dan

[KrissMotors]

thre is a direct relationship between rpm and voltage... apply more voltage, the motor spins faster. so if it's maximum voltage is 125 ac volts what does that result in for rpm. You need to know that to determine gear ratios, top speed etc...

At 125v the AC-75 (or AC-50) will rotate at very high RPM, easily over 8000, but torque falls off well before that, greatly limiting the usefulness of the higher RPM ranges. The AC-75, for example, begins to lose torque around 2,500 RPM and doesn't have much punch after 5,000 RPM or so (about 50% of peak torque). It would keep a vehicle at constant speed at 5000-6000 rpm since that doesn't take much power, but acceleration would be sluggish.

Assuming a 2.88 5th gear ratio on a stock Impreza TY574*** transmission and an average tire rotation of 10.4 turns per one mile per hour, a speed of 100mph would be about 3,000 RPM, very comfortable for either the AC-50 or AC-75.

[BipDBo]

Just curious...If you just need standard household electric to charge up the batteries, then couldn't you figure out how to mount a portable generator in the front of the car and run that to recharge the batteries while you're driving?

Wouldn't that extend the range if needed?

Granted, you'd probably be limited in the size of the gas tank that could feed the generator.

That's how the Fisker Karma works. It's called a series hybrid when the engine turns a generator which powers a motor / charges batteries. Diesel trains also work this way. For the Karma, it doesn't work so well. It's not very efficient in range extending mode, something like 20-25 mpgs. Parallel hybrids, which divert some of the energy mechanically from the engine to the road, typically are much more efficient. The Prius s a paralelel hybrid. The Volt (in range extending mode) is a series hybrid at lower speeds and parallel hybrid at highway speeds.

[Xusia]

Using "rounded" numbers

it takes 12 -13 hp to go 65 as a generic estimate (drag coeff, frontal area, rolling resistance)
1 hp is 746 watts
at 125 volts, that is 6 amps
so... 13 hp is 78 amps at 125 volts, you have a bunch of effeciencies that come into play, I'd assume 75% as a starting point so you would need 104 amps That would require an 18-20 hp generator

Dan

That should equate to about a 12-14 Kilowatt generator. Looking at traditional generators, that's a bit costly and a lot bulky. There MUST be a better solution... I mean, a 250cc motorcycle engine puts out more than 20hp and isn't as large as a 12Kw generator - not by a long shot.

Thinking about it, really what you need is torque, not HP, to turn a generator. So maybe a small ATV engine could be used instead. I dunno... Gonna think about that some more...

[Vman7]

hmmm..........there should be an old washing machine motor around here somewhere.......that should have plenty of torque, I know it sure puts my pants in a twist from time to time........lol

[Nelff]

just... yes...

[flynntuna]

This could be a look for the high mileage version.15891

[RM1SepEx]

That should equate to about a 12-14 Kilowatt generator. Looking at traditional generators, that's a bit costly and a lot bulky. There MUST be a better solution... I mean, a 250cc motorcycle engine puts out more than 20hp and isn't as large as a 12Kw generator - not by a long shot.

Thinking about it, really what you need is torque, not HP, to turn a generator. So maybe a small ATV engine could be used instead. I dunno... Gonna think about that some more...

torque x rpm = hp watts measure power too 746 watts = 1 hp nothing is 100% effecient

simple math... sorry numbers don't lie, you want to generate DC power and feed the batteries not ac power to feed the motor

many ways to get there & a std gen set too heavy, small diesel? Small turbine? Japanese bike engine? options abound... my 84 volt reverse trike can be recharged using one of these spun up to the correct RPM
http://www.thunderstruck-ev.com/motenergy-me0709.html

or go this route... backup small diesel hybris http://www.rqriley.com/ XR3

[bromikl]

One of the reasons I am interested in a hybrid is that the generator can be relatively small compared to the size of the vehicle. It only takes 25-50 Hp to keep a car moving at highway speeds. A diesel engine can be extremely efficient when tuned for a specific RPM. The car would need a small battery (I'd say enough to go 5-10 miles at 60 MPH) would be plenty for many trips we currently use our cars for. To add range, simply start up the generator!

[Xusia]

...you want to generate DC power and feed the batteries not ac power to feed the motor...

Actually, my preference is that the generator DOES feed the engine directly. That allows the system to at least "limp along" even in the event of the batteries being completely drained, or even worse (i.e. damaged). However, the batteries have to convert DC to AC (assuming an AC motor, which is not a foregone conclusion), so there shouldn't be any reason why the DC output from a generator couldn't be wired into the same DC to AC converter.


One of the reasons I am interested in a hybrid is that the generator can be relatively small compared to the size of the vehicle. It only takes 25-50 Hp to keep a car moving at highway speeds. A diesel engine can be extremely efficient when tuned for a specific RPM. The car would need a small battery (I'd say enough to go 5-10 miles at 60 MPH) would be plenty for many trips we currently use our cars for. To add range, simply start up the generator!

The idea you describe is what I believe is ideal. It's unclear to me if you are talking about actually having the engine send power to the wheels, or just provide electric power to the motor. I'm talking about the latter, because I would prefer to keep it simple (no transmissions, differentials, etc.).

[RM1SepEx]

You want to continuously "feed" the controller that means a dc generator, if the battery has no capacity left, the generator will just "feed" the controller. The question is how much do I really need. I would argue that 40 -50 miles of pure battery power would do it with a generator capable of the amps needed to go 60-65 in steady state flat topography cruising... make it barely able to keep up.
then when you plan on going farther acceleration, hills drain charge when the generator is running, braking or letting off the throttle replenishes the battery... going slower than 60-65 recharges etc...

In theory this is the Volt's concept... BUT they have a behemouth of a generator... why????

[BipDBo]

https://www.factoryfive.com/whats-new/west-philly-high-school-students-build-gtm/
The West Philly High entry to the x-prize, which built on a factory 5 GTM is a through the road hybrid as I described. An engine (in this case, a diesel) powers the rear wheels. An electric motor powers the front wheels and can also be a generator to rechange the batteries through regenerative braking, or even while cruising, deriving power from the engine, mechanically, "through the road." The result is a plug-in AWD hybrid. There are many examples of this architure, including the Audi R18 diesel electric hybrid, which won Le Mans. It just uses an electric flywheel instead of a battery. Here's a new car with this same architecture using a battery:
http://www.autoblog.com/2013/03/07/sbarro-react-e-v-geneva-2013/
The 818 invites this because due to the Subaru donor parts, it would be very easy to put axles and attach a motor to the front wheels. You could easily move the radiator to the back of the car making room for the motor, controller, etc. Locating the battery pack may be a challenge. You may be able to build it flat enough to put it under the seats, or maybe even between the seats. The batteries on the zero motorcycles, for example are pretty compact.

[ehansen007]

Yea thats why the Tesla was such a great track car??? They took one of the best, the lotus and they should have been able to make it better according to your desires. Sorry it just isn't true, if it was we would se electric cars racing all over the world against fossil fuels, but we don't. I have only seen EV's do well in a drag race.

If it's such a great idea ....bring it on............. were holding our breath.

Well, that's partially true but we have to look at the fact that most races are sponsored by fossil fuels so the push to get electric going is just not there. However, there are already attempts to bring it forward. I was seeing electric motorcycle races at MotoGP three years ago and they were fast enough to be on the grid. As well, we're seeing more battery influence in all motorsports, but again, until big oil starts to own it, you won't see it as the main event on Sunday.

[Bob_n_Cincy]

15924
I was seeing electric motorcycle races at MotoGP three years ago and they were fast enough to be on the grid..

15923 Hi Eric, in 2010 the Lightning motorcycle team won the TTXGP North American Championship. Our most recent victory was the e-power race at LeMans France. I am the propulsion engineer on the team and my 818RSe will be electric powered.

[wleehendrick]

I am the propulsion engineer on the team and my 818RSe will be electric powered.

Very cool! But then shouldn't your change your avatar to an electric motor :confused:

[Bob_n_Cincy]

Very cool! But then shouldn't your change your avatar to an electric motor :confused:
Changed :)

[bromikl]

The idea you describe is what I believe is ideal. It's unclear to me if you are talking about actually having the engine send power to the wheels, or just provide electric power to the motor. I'm talking about the latter, because I would prefer to keep it simple (no transmissions, differentials, etc.).

That's my thought, as well. On the sub, we would "float" the battery on the AC electric system using a massive AC-DC motor-generator. At automotive power levels, the same can be accomplished with electronics and fewer energy losses. While technically on the same distribution bus, I imagine the current as constantly charging the batteries. But due to changes in load, the batteries would actually be charging and discharging a small percentage of their full capacity.

[nucleus]

Well, this really comes down to torque and curb weight. If you can get a maximum amount of torque to the rear wheels for a given curb weight, this will result in the fastest acceleration, all others things (like the driver) being equal. The torque curve of an AC-75 electric motor is FLAT between 0 and 2000 rpm at the maximum torque level. No internal combustion can match that. If you can shift fast enough, it seems - at least on paper - that an electric 818 would beat a gas-powered version.

Our friend Kriss needs some remedial physics instruction, there is no way that a an AC-75 will be anywhere close to as fast as a WRX engine, no way at all.

Kriss, the piece that you are missing is the time component, torque is just a force, to do work like accelerate a car you need to know how often you can turn that shaft with that torque 360 degrees. When you know that, that is force x time which is POWER, and it is power that accelerates a car.
'
'That said, Kriss is 100% correct on not needing a BMS... These are built by people who don't really get the LiPO4 battery chemistry, and they are the cause of most if not all electric car fires.

The LiPO4 chemistry is extremely stable, they do not heat up and catch on fire like the LiCrAl chemistry used in drills, Teslas, and Boeing 787s. They don't require cooling, and if treated right will last well over 8000 cycles. They are great batteries for an electric car! Don't buy a Black Magic System (BMS).

[RM1SepEx]

The BMS or no BMS debate is not settled. Calb http://en.calb.cn/comm/?id-164.html and Winston (thundersky) http://www.electricmotorsport.com/store/ems_ev_parts_batteries_LFP_win_180ah.php both rec BMS systems for their batteries. Many experienced electric vehicle companies use BMS with LiFePO4 systems. Life cycle is dependent on avoiding over and undercharging

The key to useful electric vehicles is energy density, it is so low in a battery vs a gallon of liquid fuel that you can't afford losses, both mechanical and electrical. The system needs to be as simple as possible and you need to avoid power conversion (mech to electrical, ac to dc, gear reduction or multiplication) as much as possible. Each carries with it reductions in effective use of the power available (10% or more in many circumstances). Lower weight, better aero, etc... are all due to the inherent low power storage density of batteries.

I think that a 250 Kawasaki Ninja motor motor driving a DC generator at the desired voltage would make a very good serial hybrid setup for best range when needed. Buy expensive batteries to cover your 90% of the driving time, day to day commute. Size the generator for power needed to offset 70 mph cruising on flat ground.

That is why the production systems are high voltage, high rpm setups. Pump high currents to accelerate, use low currents at higher voltages to cruse with low power consumption.

Nucleus is correct acceleration is all about power under the HP curve, not about torque.

[nucleus]

The BMS or no BMS debate is not settled. Calb http://en.calb.cn/comm/?id-164.html and Winston (thundersky) http://www.electricmotorsport.com/store/ems_ev_parts_batteries_LFP_win_180ah.php both rec BMS systems for their batteries. Many experienced electric vehicle companies use BMS with LiFePO4 systems. Life cycle is dependent on avoiding over and undercharging

The key to useful electric vehicles is energy density, it is so low in a battery vs a gallon of liquid fuel that you can't afford losses, both mechanical and electrical. The system needs to be as simple as possible and you need to avoid power conversion (mech to electrical, ac to dc, gear reduction or multiplication) as much as possible. Each carries with it reductions in effective use of the power available (10% or more in many circumstances). Lower weight, better aero, etc... are all due to the inherent low power storage density of batteries.

I think that a 250 Kawasaki Ninja motor motor driving a DC generator at the desired voltage would make a very good serial hybrid setup for best range when needed. Buy expensive batteries to cover your 90% of the driving time, day to day commute. Size the generator for power needed to offset 70 mph cruising on flat ground.

That is why the production systems are high voltage, high rpm setups. Pump high currents to accelerate, use low currents at higher voltages to cruse with low power consumption.

Nucleus is correct acceleration is all about power under the HP curve, not about torque.

Well your post proves that you are right about the BMS debate!

I want to talk hybrid systems then I will finish up with BMS.

I think that looking at what the upcoming BMW i3 is doing with it's range extender is enlightening. They are using a 650cc engine attached to a generator that we don't know the details of yet.

RM1SepEx is absolutely right about energy density being the bugaboo with electric vehicles. With LiPO4 chemistry you are looking at over 400 pounds for the equivalent energy of 19 pounds (three gallons) of gasoline.

There is something that is not obvious to many in the EV world. the battery manufacturers themselves either don't understand or don't communicate correct information about their own batteries. It must be a chinese cultural thing. They give self-discharge rates for batteries that do no self-discharge. Their C rates are way off. You can take the factory spec sheet and just throw it into the trash for what it is worth.

So when you link to pictures of BMS systems made by the manufacturers it means nothing.

By the way, you do realize that Winston hasn't sold a battery for years, right?

The problem I see with BMS systems are threefold:

1) They all try to "top balance" which makes no sense at all, as the voltage bounces around so much at the top of the charge.

2) They use voltage to make decisions about the cells, and voltage fluctuates greatly under load. A lot of BMS start shutting things down when you get a good draw down on your pack, even when they are well charged.

3) The whole idea behind the BMS is to individually charge each cell to compensate for "cell drift", but "cell drift" DOES NOT EXIST with LiPO4 cells. Their reason for existing is made up! The kicker is that the BMS people can show you the cell drift, you know why? Because it is caused by the BMS! It is like selling fire extinguishers that cause fires! Oops, did I say fires? While discussing BMS systems? Oh the irony.

Have a good one,

Nucleus

[Xusia]

I think that looking at what the upcoming BMW i3 is doing with it's range extender is enlightening. They are using a 650cc engine attached to a generator that we don't know the details of yet.

This is what I would consider if building an EV (I haven't yet committed to any particular 818 build path yet), and hence my question in the other thread.

[RM1SepEx]

nucleus, ....As I plainly stated in my opening statement, all my post does is indicate that both the MFGs and reputable users, developers, vendors go both ways on BMS. Some like/use them, others don't. The "experts" that I have worked with had no issues with fires, BMS was focused on battery life. I have no doubt that since we are dealing with China many half cocked excuses for BMS have caused problems... fires? sure tons of energy to harness or release involved.

[Speedy G]

Hey KrissMotors,

(Going back to the first message on the thread...) I'm interested. I like your choice of batteries, but check the discharge rate vs weight to make sure you got what you need. Check out all-battery.com for LiFePo4 batteries. Also, let me know if you have a better provider.

Regarding the electric torque vs RPM thoughts, I'll just say this: When US Le Mans was about to launch, I worked on a "Patriot Project". The Specs of the car were, "as much torque as the wheel hubs can handle"!

Transmission... Why? With an electric motor I can go 0-200mph in first gear!!!! (as long as the wheel hub can handle it). I'm talking Chrysler Motor Company here, not some Jap or German wanna be crazy super car. Yeah, and that was in Boston, 1993. The Hp figure was 750hp at 16,000RPM with a top RPM at 24,000. Torque can be figured out by any with linear math skills, but essentially came down to this... 150% torque (limited by electronics) at 0RPM and FLAT, yes totally FLAT torque to 16,000 RPM, then steady descending torque to 24,000RPM. Yes that's crazy and 20 years ago...

... and it was a hybrid. To top it off, 2 turbo-alternators (think of two jet engines about 6 inches in diameter hooked up to alternators) were designed and built. Also, a flywheel spinning at 80,000RPM weighing 80 lbs was also built to make sure acceleration off the turns was crazy fast (formula 1 KERS anyone?). AND a control unit weighing 110 lbs. Guys that's 3.5MW of power, the same as the city block you live in, in a package weighing 110lbs and about a yard by 1 ft in size... ... in 1993...

Yeah, MIT's in Boston... What I'd like to see is an 818 extremed out the electric way... My issue is that I can't make up my mind whether I want a '33 with a blown coyote or an 818 with a turbod VR6 or an 818 with a seriously crazy electric engine in there... I wish I had the time to have all 3...

Btw the company that built the motor in the Patriot Project was Satcon. These days they don't own their motor division anymore (Ugh!). But, there's cool motors out ther btw (http://www.yasamotors.com/technology). There's different electric motors too though. DC motors are usually what are used in conversions, they're high on torque but suck at high RPM. AC induction motors have a weird start-up (unless you do some crazy math and have tons of sensors at startup), but go very high RPM (limited by supply voltage, not mechanically). AC permanent magnet synchronous motors are awesome since they can do high RPM, but can also have very high torque/HP in very small packages.

Electric motors aren't the problem. What we need is BATTERIES!!! It's actually really amazing that Tesla can build a car that can theoretically compete with BMW's M5, where the batteries cost half as much as the entire car!!! Yeah, that's where we're at... the energizer bunny will determine how much torque we'll have...

In any case, kudos to Dave, FFR and the community! I'm thinking the 818 is the top tinkerer's kit out there. The best torque source is still to be determined...

Speedy G