So yeah, I ran for a few years (maybe 6 - 8k miles) on Volt modules, 24kWh pack in 4 parallel strings, each 36S (3 x 2kWh(12S) modules in series per string). The entire time with no BMS or balancer whatsoever. And eventually I lost 1 cell, and only noticed during a routine voltage check of the individual 12S modules, which did in fact wander only slightly from each other in voltage - and one of them being particularly low alerted me to the dead / dying cell which was by then starting to drain my entire pack slowly, while also over-charging the other cells in the string. I believe it would not have happened if I had used a balancer. That said, the rest of the entire pack is fine. 43Ah x 4 parallel = 172Ah pack. I often pushed ~250 amps (~1.5C) on acceleration but usually pulled 100 - 150 amps (<1C) for normal driving.
I use the same Volt modules in my Solar Energy system. The cells wander very little - on the order of a few 100's from each other - throughout the entie pack (like for example 4.01, 4.02, 4.01, 4.02, 4.04, 4.01 etc). Those that wander more noticeably, get a balancer for a few days evey few months. And they behave wonderfully.
I wasn't ready for the mess of wires or hasstle that would be 4 parallel 36S balances wired up in my car, each set interconnecting the 3 modules in series. But now that I lost 1 cell and thus 1 usable string, I wish I had done it. But those batteies will go to other fun projects. I have a new set of 40 x 200Ah LiFePO4's so now I get to have one big string, and I damn sure will wire in that balancer - a pair of 25S 5Amp active balancers, overlapped to cover the entire pack. I think I'm going to make a voltage view screen with a hand full of Cell Meter 8's. Have my own little BMS for a fraction of the cost (under 200 all told)...
Cheers!
I use the same Volt modules in my Solar Energy system. The cells wander very little - on the order of a few 100's from each other - throughout the entie pack (like for example 4.01, 4.02, 4.01, 4.02, 4.04, 4.01 etc). Those that wander more noticeably, get a balancer for a few days evey few months. And they behave wonderfully.
I wasn't ready for the mess of wires or hasstle that would be 4 parallel 36S balances wired up in my car, each set interconnecting the 3 modules in series. But now that I lost 1 cell and thus 1 usable string, I wish I had done it. But those batteies will go to other fun projects. I have a new set of 40 x 200Ah LiFePO4's so now I get to have one big string, and I damn sure will wire in that balancer - a pair of 25S 5Amp active balancers, overlapped to cover the entire pack. I think I'm going to make a voltage view screen with a hand full of Cell Meter 8's. Have my own little BMS for a fraction of the cost (under 200 all told)...
Cheers!
