So i finally put together my pack and was able to take it for a ride… i have a 12s8p pack and i experienced either voltage sag or a low battery…doesnt matter. Took apart my pack and the cells are off… 1st series group 3.793, 2nd 3.736, 3rd 3.733, 4th 3.751, 5th 3.452, 6th 3.606, 7th 3.754, 8th 3.754, 9th 3.75, 10th 3.746, 11th 3.756, 12th 3.755… i have a bms for charge and discharge but ime worried about that 5th series group… should i be or is that okay?
The bms will not balance them under 4.10v
Could you eleborate or explain that a lil further… i thought that was the whole point of the bms. To manage each series… each series being below 4.1 V
0.3v drift is a lot.
some bms won’t balance if the difference between series is too high.
try charging up your pack all the way 4.2v (50.4v) so bms goes into float charge and leave it plugged in for HOURS and see if the drift goes away.
your bms will get hot though since it’ll have to drain essentially 11 P groups down from 4.25 to 4.2 repeatedly until your 5th cell comes up to 4.2v.
my guess is you have a dead cell in the 5th group. not sure if possible but try measuring each cell’s voltage in that group and see if anything obvious is happening there.
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I have nese modules so yes, i can check each cell in a parallel group. All 8 read 3.448, no dead cell. I will try plugging it in for a few hours to see if it bring that group up
That makes it easy then, just bring the 5th group up to the same voltage, good to go.
After the charger turns green, leave it plugged-in for a LONG time, maybe even days. This is when the balancing happens. Also check that it is being corrected… it might not be since it’s so far off as @thisguyhere said
You catching this now likely saved your battery from the junk pile
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Sweet, i think i did save it… been charging it since last post and the voltage drift is only .08 now… ill let it charge longer though…but its looking hopeful…also my charger only does 48.1v… will this be an issue later or not… i couldnt find a 50.4v charger??
What charger are you using? It must be a lithium-ion charger and the correct voltage
i was lead to this by someone on this forum. They said they used this for there liion pack with no problems
I don’t think that will balance the battery if it never approaches 50.4V. Some LED power supplies can work for lithium chargers, but only certain ones. I would not use that to charge a 12S lithium-ion battery
Okay, i just unplugged it and the lowest voltage was 3.91 and highest being 4.04. I think thats good enough for now to ease my worries or a bricked batt pack. I just ordered a 50.4 v charger from some foreign place, so itll take like a month to get so at least i wont worry about my pack being ruined.
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U have to get 50.4v for float charge to kick in.
Whoever led u to that led driver did u a disservice
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Damn, well i just looked up 50.4v chargers and saw your post about the charger you use… so i got that one lol thx for everyones help.
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The one i use is slow af, for your 12s8p it’ll take forever fyi
How are your p-groups connected? Are you using only nickel strips?
Im using 3/8in pure copper tabs/bars with nese modules
Well shucks, oh well. I dont ride that much. Mostly for fun, so itll have time to charge…that and i hope i never run down this battery lol
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I’ll take the meanwell off your hands if you don’t know how to use it 
That’s one of the best chargers you can get…
HLG series 240w PSU, 48"A"djustable. I have the same unit on my desk, set to 52.5v.
This unit is actually perfect for the task at hand, being a psu and not a charger (no termination), and both voltage and max current being adjustable. And not dodgy cheap no name stuff.
2nd dibs if selling 