openinverter forum

My front BMS was giving some odd readings so i thought for safety i'd pull the pack and check things out with a meter. Good job i did as clearly the suspect module on the BMS that was previously not working at all, has now woken up and decided fiction is the way forward. Gave me a fright as it erroneously reported one cell at 4.4v and another at 2.8

So I have 330e battery, 96s across 6 modules, so i took a meter to each cell in each module and also measured the overall module voltage.
What i see is that within each 16s module the voltages are pretty even , but across the modules there is a 2.6v difference.
What is the best course of action here:-

1) not worry about it, it's a small difference
2) try and balance the modules to better match ?

why do the packs get like this, especially given as all the time they're join in parallel to another 96s pack so one would think they would even out ?

If balancing is the way to go, i can either discharge the high ones to meet the low (not sure how), or charge all to the same level. I have a 60v charger that came with an electric scooter than had lead acid batteries in it, i could apply that to each module in turn and they ought to end up even ?

thanks

Charge them all up, all the modules are under the "nominal voltage" so the differences will be quite large in voltage for a minimal difference in charge.

Aging of the modules is why they could get like this, each has different stress. Key is that the modules are matched and do not have deltas in themselves. Or for some reason a BMS slave is drawing more current off one module compared to the others.

thanks

do you think my 60v charger is ok even though it was made for lead acid ?

I also have a Surron 67.2v 10amp charger which is designed for lipo. Takes each cell to 4.2v which seems like real top end.