I mean I’m checking the series connections of the p groups. So 12 checks of the groups of 4 cells. 12s4p
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What do you do if you discover that a parallel group has become unbalanced? Do you have a 1s charger?
I raise or lower the group voltage with another cell being put in parallel. There a bunch of ways to do it but this seems easiest. A cell connected temporarily with two wires. I’ve thrown extreme variances of voltage in parallel and surprised how slow it is to balance using the 30q. It’s not instant and could take minutes…and maybe that’s a good thing. Doesn’t get beyond a hair warm
I’m hoping to find a giant resistor instead to do the same with. That’s be even easier. Do some ohms law and figure what resistance would be acceptable
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I broke and repaired 2 packs recently. It’s pretty annoying, takes forever to get series group voltages in the same place. I wire my packs so I can use my expensive hobby charger to balance, but the voltmeters in the hobby charger don’t quite agree with bms, so everything takes forever, hoqrs and hours.
What u mean “broke”?
I can take the voltages in maybe two min max. Taking the enclosure off is the pain. Next board I just made with (2) 6s balance leads to attach a lipo balance discharger
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I’ve got a quad 1.5a cell charger, is it good enough to bring them to the highest cell voltage individually? Also as long as a single cell in each p-pack is connected wont they balance out when reconnected?
I don’t know ur charger really. Is it a “wall wart” for a phone or something? They will work but I’d be careful. I’ve done that. They aren’t a regulated power supply I think. I think. So they don’t make as smooth and ideal a charge. And more worrisome some will go to a too high voltage as they’re designed to be controlled by your phones bms or whatever they call it. Some of them are stated at 5v. I think it’s fine as long as youre aware and watching voltages rise. Maybe just balance everything to 4v at least. No need to balance at 4.2 like a bms does
Drained one dry, killed 2p groups and badly weakened another 2. Couldn’t bring them back. The dead cells were interesting. Charged them up carefully and slowly. The cells got somewhat warm. Took them off charge and it kept getting warmer slowly. Got to 180f at some point. The pack spent the night outside. And in the morning the hot cells were like 1v. Haha this is the hummie deck and motors!
The other one, bms killed a p group, drained it to zero. At least it gave me a clue by not letting the pack charge. Surprisingly the board still ran, but very weak. Reuair was easy but rebalancing was a pain using a lab psu. The re-tested the bms to confirm, which meant another balancing session.
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Yes charging to 4.2 takes forever because of the CV curve. It’s faster to get them in the ballpark and drain them down for balancing.
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