this is so insane.
ive been building my own batteries for about two years now and i thought i had seen almost everything peculiar about 18650 based packs.
twice now the following has happened:
i have a board that won’t charge all the way. the BMS is cutting off the charger prematurely, say around 70% or thereabouts on the fuel guage. otherwise it runs fine, just doesn’t charge all the way or ever act fully charged. so i figure it’s orobably broken welds or maybe a bad solder on a balance lead or maybe a balance lead found a way to short, who knows. so i cut the pack open and find all good welds and solder joints. Then it’s time for the volt meter. all the cells are reading 4 volts ish and seem properly balanced.
except one p group. That one is reading 0.00v on all four cells.
how the actual fuck does this happen? why didn’t it vent or do whatever they do on over discharge? lipos would have puffed. these just sit there and play dead and affect nothing but performance.
anyway thoughts and opinions are welcome because i’m very confused right now. Also greatful because if a cell group is going to fail, this is how i would prefer it to do so.