Hey guys, in need of help. Don’t know why, but my battery setup is not working right now. The battery is a Samsung 30q 10s4p
I noticed some time ago that my battery would only charge to 94%. I got it from my friend who had a bad bms installed. Got a new one and battery seemed to charge well, still to only ~94%. Maximum voltage was around 41.3V. Today, I wanted to check what was going on in each individual group. This is what I found when the battery was at a 44% charge, around 33.3V:
As you can see, 2 groups are at 3.5 and one group reads NO VOLTAGE while the others read 3.7. I bought an 18650 charger thinking I can spot charge any groups that needed a bit of juice but that last group at the end seems like an outlier. What’s going on there? Is the entire group dead? Don’t see how that would be possible when it read a voltage of 41.3V
On a separate note, I just went to charge my battery pack, and it won’t charge at all. Charger led doesn’t turn red. Thought it may be the bms so switched it out for a new one. Nope. Not sure if it’s the charging port, it looks to be fine. Is it because that entire group is dead? I’ve never really had problems before so I don’t know why that would happen now.
I’m sorry this is a long post, but I’m really really lost. I would really appreciate any help I can get. Thanks guys.
Generally speaking if a specific parallel pack if way below voltage you should toss that parallel pack, and if the whole pack has a fair few cycles you toss the whole thing. As someone who has chosen to ignore this advice due to being unable to buy lots of new cells, I’d say just replace the one at zero volts. Chances are the BMS is actually fine but has shut down because the balance leads are reading a disconnected parallel pack
Edit: also possible its falling apart and you just lost connection to that one parallel pack
You’ll want to shuffle the cells around so new parallel packs are made from a combination of cells in a way that they have the same internal resistance. It’s a lot of work but its the best you can do with those cells
Don’t know if I’ll be able to make it 10s3p as the groups are in 4’s and taking out 10 cells would require a good amount of work. A 9s4p would work I guess
Tell you what, measure the voltage of the dead parallel pack directly, it might have lost a balance wire and be fine
The cells are old and at sub optimal capacity so they will never charge to 100 again but they might be okay still and its just the wire that failed
If the ‘dead’ parallel pack is reading a really low voltage you will need to remove those cells, and they cannot be replaced anymore since you’re at 100 or so cycles
