E46 M3 OEM vs E46 M3 CSL/Mini vs F80 M3 Li-ion Battery

[0-60motorsports]

I’ll be sticking to my CSL battery with those crazy LIION prices lol

[Tbonem3]

Yep, CSL !

[Speed Monkey]

The enthusiast car website published a guide on lightweight batteries for the E46 M3.
Here is the address:

https://thebuildjournal.com/tech-guides/ultimate-lightweight-battery-guide

Below is a excerpt from their lengthy list.

[911Fiddler]

I've been running a 6 lb Braile GU1R lithium battery in my M3 for 3.5 years now without any issues.

That said, it no longer sees winter use (though it's had a couple <30 degree starts) and I put it on a (lithium specific) trickle charger if I'm parking it for longer than ~2 weeks (... which I did with the stock battery, too).

Because, at 6 lbs, it's not doing anything meaningful for weight distribution, and the battery cable going to the trunk is 6 lbs, I also mounted it under the hood, like the 4 cylinder e46s do. Enabled me to save the weight of the cable and gave me more trunk space!

Superb innovation!
After a battery relocation test I ran, where I put the std battery in the middle of the rear boot (trunk) space, I had been considering running two small lead-acid batteries (stop-start series) in parallel either side in the boot. I could definately feel an improvement to handling with the mass centralised at the rear. Ive not acted yet on my plan, time now to do some more investigations at this end (UK).

[pawa_k2001]

Found my next battery, i48CX Braille. Stock size, no worries about keeping it on a charger. Jump in an go while saving 35lbs over stock battery.

[GreyM340i]

Found my next battery, i48CX Braille. Stock size, no worries about keeping it on a charger. Jump in an go while saving 35lbs over stock battery.

Is your car a gutted race car? Why pay $1500 for a lighter battery? Not sure I understand what 35lbs will do for 90% of the people driving these cars?

[pawa_k2001]

Is your car a gutted race car? Why pay $1500 for a lighter battery? Not sure I understand what 35lbs will do for 90% of the people driving these cars?

I am aiming to have a 2999lbs street E46 M3 with 5/8th tank of fuel. I am currently at 3053lbs and looking at every option since I can not remove the comfort features like A/C, cruise control, leather seats, insulation and carpet.

[repoman89]

Found my next battery, i48CX Braille. Stock size, no worries about keeping it on a charger. Jump in an go while saving 35lbs over stock battery.

Why pay that much vs the Antigravity equivalent? Just got the 30Ah H6 size for $450 used, it’s a couple hundred more new. It’s 10 lb, LiFePo chemistry and also doesn’t need to be kept on a charger.

Deleting the battery cable and putting it in the engine bay as some have done is tempting too but I’m a lot more comfortable with lithium in the trunk.

[pawa_k2001]

My new battery came in, 11.15lbs!

[Obioban]

I've been running a 6 lb Braile GU1R lithium battery in my M3 for 3.5 years now without any issues.

That said, it no longer sees winter use (though it's had a couple <30 degree starts) and I put it on a (lithium specific) trickle charger if I'm parking it for longer than ~2 weeks (... which I did with the stock battery, too).

Because, at 6 lbs, it's not doing anything meaningful for weight distribution, and the battery cable going to the trunk is 6 lbs, I also mounted it under the hood, like the 4 cylinder e46s do. Enabled me to save the weight of the cable and gave me more trunk space!

new battery location (and my super leggera washer tank):







Extra trunk space:



Bonus: I also got extra trunk space on the passenger side

Now at ~6 years, no issues.

[Obioban]

Is your car a gutted race car? Why pay $1500 for a lighter battery? Not sure I understand what 35lbs will do for 90% of the people driving these cars?

Nothing improves how well a car drives, including on the street, more than weight.

[eljay]

Now at ~6 years, no issues.

Is this setup suitable for a daily driver? What if I had to run errands around the city with multiple short trips and starts in a day? Any concerns about having enough juice to start every time?
You did keep the pyro fuse on the cable, correct? I think I see it there, so just making sure. Any concerns about that thing firing in an accident scenario so close to the engine bay even if it's in a separate compartment? I guess the wall separating it from fuel lines is about the same as the sheet metal separating it in the rear from the fuel tank, right?

Thanks!

[jet_dogg]

Is your car a gutted race car? Why pay $1500 for a lighter battery? Not sure I understand what 35lbs will do for 90% of the people driving these cars?

Even I wouldn't pay that, and that's saying something.

[Obioban]

Is this setup suitable for a daily driver? What if I had to run errands around the city with multiple short trips and starts in a day? Any concerns about having enough juice to start every time?
You did keep the pyro fuse on the cable, correct? I think I see it there, so just making sure. Any concerns about that thing firing in an accident scenario so close to the engine bay even if it's in a separate compartment? I guess the wall separating it from fuel lines is about the same as the sheet metal separating it in the rear from the fuel tank, right?

Thanks!

My car sometimes functions as a fair weather DD, depending on my mood. I've never had any battery issues. I do plug the car in if it's going to be sitting for longer than a ~week.

I did keep the pyro fuse. BMW put the battery in the location I'm using in 4 cylinder e46s, including the pyro fuse, so I'm reasonably confident it should not be creating any safety issues.

[eljay]

My car sometimes functions as a fair weather DD, depending on my mood. I've never had any battery issues. I do plug the car in if it's going to be sitting for longer than a ~week.

I did keep the pyro fuse. BMW put the battery in the location I'm using in 4 cylinder e46s, including the pyro fuse, so I'm reasonably confident it should not be creating any safety issues.

Thank you! And yes, good point about the 4-cyl setup already being OEM approved.