Lithium car batteries; 1 3rd the weight

[redpoint5]

Originally Posted by serialk11r

Ah, I never bothered checking the prices of individual cells haha. 7Ah for 3.50 is a good deal, 4S6P would be 84 bucks so much less than 200 for the assembled pack.

I also realize people use batteries in far more demanding settings with no individual cell balancing, but... it's "correct" to use a BMS and not fair to compare directly to BMS equipped batteries.

In a car, I think having the original fitment plastic case, SAE post terminals, and a BMS, all assembled, is well worth an added 120 bucks.

BMS from Aliexpress is a few bucks more.

I bought some balancers and intend to use them going forward. Don’t care for full BMS though as it’s just another parasitic load.

[serialk11r]

I like having low voltage cutoff feature because I've damaged batteries by leaving the car sitting too long before. I went for "200A" on my LTO battery which cost 100 dollars for the BMS since it has enough MOSFETs to cover my whole palm to pass all that current XD

Realistically for a car that's either frequently used, kept charged, or has low parasitic drain, I would be okay with just passive balancing using diodes.

IF you look at EV battery packs, some of them are only balanced across 10S sub packs, and I don't think laptop batteries or RC car batteries are balanced, and I don't think people who bought earlier lithium ion batteries with balancing ports really use the balancing ports, so no balancing is probably okay but it's cheap enough that it doesn't really hurt.