Help needed selecting battery mk5

[Genedmk5]

Manual states using group 96r battery (latest manual)
My frame is one of the earlier ones that since have been changed for mounting the battery. (Modifying it would involve cutting and welding) There is no way you can get a group 96r in and out without updating the frame. Anyone know of a smaller battery that would work with a coyote. The opening thru the bottom would need a battery about 6x9 to make it up in.

[edwardb]

I have a Odyssey Battery ODS-AGM28L Extreme Series AGM Battery in my Mk5. Same as in my Gen3 Coupe and 35 Truck. Frequently see this same battery in Factory Five's builds. It measures approximately 6.5 wide, 5 high, 7 long. Per a search, a 96R is 9.5 to 9.6 inches long, 6.8 to 6.9 inches wide, and 6.9 to 7.5 inches high. Bigger than the Odyssey. My Mk5 frame is the older design as well. I would not expect either of these batteries would fit out the bottom of the older design frame. I've had to switch out the battery in my Coupe and the Odyssey battery lifted out the top with the cold air intake removed. Not a big deal and I'm expecting the Mk5 to be similar. Don't know if that would be the case with the 96R.

[J R Jones]

Dimensions aside, the enegy spec for the ODS-AGM28L is 330 CCA. I don't know how that manages a V8.

My Fiat Abarth 1400cc has a small 96R battery with 600 CCA.
My AC 5.0 has a small 26R with 675 CCA.
My Acura 3.5 has a mid-size 25F with 700 CCA
The recent WI weather has been a battery challenge. Maybe the Odyssey has some other compensating majic.
jim

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[edwardb]

Dimensions aside, the enegy spec for the ODS-AGM28L is 330 CCA. I don't know how that manages a V8.

My Fiat Abarth 1400cc has a small 96R battery with 600 CCA.
My AC 5.0 has a small 26R with 675 CCA.
My Acura 3.5 has a mid-size 25F with 700 CCA
The recent WI weather has been a battery challenge. Maybe the Odyssey has some other compensating majic.
jim

How about experience. I've been using that battery for multiple builds including high end SBF, LS3, and Coyotes. Never an issue with starting or anything else. As I mentioned, Factory Five also uses them. I don't know that I'd leave it outside overnight in the Michigan cold. Minus 7 this morning. But then these cars don't typically experience that. My recommendation stands.

[rich grsc]

I have used an Odyssey PC-680 for 6 years, it is rated at 170A. It has never had an issue starting my 10.5 to 1 compression 331. It has an inrush amp rate of 520A, continuous rate of 170A, the AGM-28L has an inrush amp rate of 675A, continuous rate of 275A
More than enough for a V-8

[J R Jones]

"Inrush amp rate", that is a new aspect to batteries for me. Note:

AI Overview
Battery inrush current is an instantaneous, high-amplitude current burst drawn when equipment is activated, often exceeding 20 times the normal operating current for a fraction of a second. For 12V automotive applications, inrush typically ranges from 255 to over 1,000 Amps during engine starting.

Key Aspects of Battery Inrush Current.
Automotive/Starting: A standard 12V car battery delivers 400–800 Cold Cranking Amps (CCA), while diesel engines often require 300+ Amps of inrush.
Motor/Load Start-up: Motors initially draw 4 to 8 times their rated current for several seconds, with the very first half-cycle often exceeding 20 times the nominal, or full-load, current.

I might assume quick starting is less of a challenge. Prolonged cranking may benefit from bigger CCA numbers.

In the case of my 1400cc Abarth it is a high performance turbo (160hp / 21lb boost) with multi-air valve actuation.

MultiAir System: This system controls intake valves electro-hydraulically rather than with a direct camshaft connection. A high-pressure oil chamber between the cam and the intake valve, managed by an ECU-controlled solenoid, allows for variable lift and timing to optimize power, torque, and emissions.

After prolonged storage the valves do not open untill after significant cranking to develope oil pressure and chamber "pump-up".
jim
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[Jeff Kleiner]

Well you know JR, starting a modern EFI engine doesn’t involve cranking and cranking and cranking some more while pumping the pedal and pushing and pulling on the choke like an old Fiat. They generally fire after about 2 revolutions…so there’s that ;)

Jeff

[J R Jones]

Jeff,
Once upon a time I built a 1300cc RX7 rotary with a hand choke, but no pistons and no valves. It did very well with 200hp.

More recently my latest has no pistons, no valves, no EFI, no exhaust and it makes 1000hp. One does have to hang-on.
jim

[Genedmk5]

Thanks for the response.
Just made up a dummy cardboard battery with those dimensions and looks like it’s a winner. It will work from the bottom after making the tray removable. Plenty of room to put the battery in first then bolt the tray down.
It would go in from the top if not for power steering unit we added.
I agree this may not work well where I live now. 16 degrees out now, you need a pretty big battery around here now.

[rickster991]

I saw this in some of the FFR pictures. It fits fine and does the job. I do not recommend the mount.

https://www.summitracing.com/parts/xsp-s925


https://youtube.com/shorts/aWu9vFMqhpc?si=Yu4FchDg8gEzRGI1

[Mike.Bray]

Well you know JR, starting a modern EFI engine doesn’t involve cranking and cranking and cranking some more while pumping the pedal and pushing and pulling on the choke like an old Fiat. They generally fire after about 2 revolutions…so there’s that ;)

Jeff

Exactly That's why I can't wait to get rid of the carbed engine in my 68 Camaro and get the new EFI 427 installed. Starting it is always an event.


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224885

[rponfick]

Just for info purposes, I have a Group size 35 in my MK5, early model, with PB 347" with their front pulley dress up kit. I had to take the dress-up cover off the front of the fan pulley to get it in. So, close, maybe 1/4" of fitting.
Ralph

[Aleinsteingenius]

I have the older style Mk V frame as well. I am installing the 7.3 L Godzilla motor, so whatever I do will need to be strong enough to crank over that beast. I have the power brake booster, which looks like it will prevent battery removal from above with a standard battery. I am contemplating cutting the frame tubes out so I can install the newer battery box that will let you remove it from below OR maybe using two larger motorcycle batteries wired in parallel that are thin enough to remove from above.

[rich grsc]

Well Mike that has a serious problem. :( Someone put the distributor on the wrong end of the block, and when you spin the engine around, it's going to drive backwards.

[Mike.Bray]

Well Mike that has a serious problem. :( Someone put the distributor on the wrong end of the block, and when you spin the engine around, it's going to drive backwards.

You're right! I also noticed the oil pump is on the wrong end and the distributor rotates backwards.

It reminds me of the time I connected my battery backwards. The radio listened and the horn sucked.

[J R Jones]

Gene, Rick,
Looking at the packaging of the MK5 batteres in this thread, another aspect should be considered, high temperture.
When I worked in Harley Davidson development, lead acid batteries lasted a season, rarely two seasons. In the southwest battery life could be less than a season. Complicating the ambient temperature was nesting the batteries next to the dry sump oil tank. At 100F we determined the metal plates in the battery warped. Vibration caused the warped plates to rub through the insulation and short to the adjacent plate, dropping output.

AI Overview
Temperatures exceeding 80°F to 90°F 27 to 32 C are generally considered too high for lead-acid batteries, as excessive heat accelerates degradation, causes rapid self-discharge, and leads to permanent damage. For every 15F rise above 77F, battery life is roughly halved. Key Temperature Thresholds: Ideal Temperature: 70F to 80F is optimal for performance and life. Damage Threshold: Temperatures above 80F begin to accelerate degradation. Critical Danger: Temperatures exceeding 125F are considered dangerously high, leading to rapid, irreversible damage.

Consider the temperature influence of the radiator, hoses, engine and oil coolers to battery life. having the battery in back is not just for weight distribution.

The Odyssey is more tolerant of heat:
AI Overview
The Odyssey Battery ODS-AGM28L Extreme Series (PC925L) is an Absorbed Glass Mat (AGM) battery engineered with Thin Plate Pure Lead (TPPL) technology, designed specifically to withstand high temperatures better than conventional flooded or standard AGM batteries. Despite this, prolonged exposure to extreme heat remains a primary cause of capacity loss and reduced service life.
Influence of High Heat on ODS-AGM28L Performance:
Operating Temperature Range: The battery operates effectively between -40°F (-40°C) and 140°F (60°C).
Maximum Heat Tolerance: Models equipped with a metal jacket can withstand extreme, short-term temperatures up to 176°F (80°C).
Reduced Lifespan: While designed for a 3–10 year service life, constant exposure to high temperatures will reduce this lifespan. A general rule of thumb is that battery life is cut in half for every 15°F–18°F rise in temperature above 77°F.

jim

[bobl]

A good (Antigravity, etc)lithium ion battery would solve all the problems, cool but very expensive.

Bob

[Aleinsteingenius]

I have been looking at the various lithium motorcycle batteries to solve the problem.

[Nigel Allen]

It's not often I have some real world experience to offer this forum, but I have done cranking measurements for my Coyote using calibrated instruments. I did this a number of years ago for a fellow on the forum to answer some questions regarding cable size from a rear mounted battery to the starter motor. My roadster has gen1 coyote and 1.1kw reduction starter. Battery is basic lead acid, mounted in recessed battery box in floor of trunk. I used 70mm2 battery cables, which gave negligible volt drop while cranking.

Average cranking current was 100amps at 11.5VDC (measured at starter). Captured peak current was ~220amps on initial crank. The reduction starter is impressive. It spins the engine easily. I am sure the cranking current would be higher for different engines. However the OP has stipulated Coyote.

I have never had issues with starting even in cold conditions. However, our cold conditions do not match what is experienced in the US. Mind you, I don't think I'd be bothering to try and start my car in colder conditions than what I have experienced. I would rather stay inside and watch TV.

Hope this is helpful information. Jim brought up some really good points as well regarding how temperature can degrade batteries. I have 25 years experience working with industrial UPS and their associated battery systems, as well as a motorcycle pastime. Can attest to Jim's post.

The only disadvantage I have experienced with a small capacity battery in my roadster is related to the standby draw from the ECM, immobiliser and clock. Max I can go between starts is 6 weeks. Generally if I am parked up beyond that, I will open the battery isolator.

Have never used a battery tender, because this electrician was too slack to install an easy connection point.

Cheers,

Nige

[Pete&Scott]

You might look at powersports batteries. ATV, UTV, etc The are a little larger than motorcycle batteries and could be hooked in together. You could then take one out at a time if you need to swap them out. I run a lithium battery in my Honda Africa Twin. It works so much better than a lead acid. I also have Lithium batteries in my 5th wheel toyhauler. Lithium batteries are not as expensive as they used to be.


I have been looking at the various lithium motorcycle batteries to solve the problem.

[Nigel Allen]

As Pete&Scott, and Jim point out, lead acid motorcycle batteries aren't a great choice. Another reason that their life is short is due to the space saving construction. In a motorcycle battery, the plates extend to the bottom of the battery casing, whereas a car battery plates have a 10-15mm gap between the plates and the bottom of the plastic casing. As the battery ages, flakes form and drop off the plates accumulating in the bottom of the casing. This causes a problem for the motorcycle battery, as the flakes having nowhere to go, short out the plates, leading to shortened battery life.
Lithium, (despite its own set of issues), with its reduced weight / greater capacity, longer life seems to be the answer.

If you wish to stick with conventional lead acid, trunk mounted is likely a good solution. After all, an FFR trunk isn't good for much else. I have seen bigger lunch boxes.

[rich grsc]

The PC-680 is considered a motorcycle batter...6 years starting my car, never use tender and it has sat for 3 months and started the car. As for heat in the Mk5 location, not an issue as there is a TON of air moving all around the front of the car. Th heart from the radiator is immediately defused with the cool air moving around the front. I have an intake charge temperature sensor mounted on the top of the engine between the stacks, even on 90* days it will rarely get above 100* while moving , and there is less airflow in that area than behind the radiator

[J R Jones]

As long as we have become technical on this subject, heat is not a static influence. Heat tranfers from the engine and cooling devices by radiation and cooling system circulation (transfer).
My running temperatures are stable under way but they increase at idle and after the engine is shut off. The airflow and coolant circulation stops. The result is called heat soak. All the heat is released through radiation. Other than the radiator fan, there is no airflow.
The heads are the hottest part of the engine because of the combustion chambers. The intake is the coolest part of the engine because of intake airflow and the evaporation effect of fuel atomization.
There are carburetor nay-sayers here that probably have never seen carburetor icing above 32F ambient, but it happens. Remember heat stoves as a part of air cleaners?

When Harley came out with the FLT (Road Glide) touring bike, the one piece fuel tank was large and airfow masked by the frame mount faring. When the bike was stopped hot, the radiant engine heat caused the fuel to boil. Gasoline starts boiling at 122F to 155F. That did not happen while riding, but it gets your attention at a fuel stop.
jim

[Myron Nelson]

I have an early MK5 with the power brake booster. I went to Autozone and got a 151R-DLG. From underneath you can pass it up and then forward onto the tray. Plenty of starting oomph for the Coyote.

[rich grsc]

Well this isn't a Harley, and there is a bunch of room around the battery for airflow. So who cares about Harley design problems and QC issues