BMS anomaly

[zzrider]

Hi guys,
Using 48V Lifepo4 40Ah 16s3p pack with general BMS type YS90808 but the problem is: 8-th cell will be charged way over, comparing to others. The allowed charging voltage for this type of cell is 3,65V but the BMS shoots 3,9V to the cell 8, others are OK, between 3,6...3,65V. I´ve seen this pattern on other packs too with the same BMS.
Any idea what is causing this behavior and how to fix this?

 

[amberwolf]

If it's always the same cell number that has this problem, regardless of what connector/wires/cells are connected to the BMS, then you'd need to check that channel on the BMS, while cells you know are actually at equal voltages are connected to it and another channel, to see which points on the channel are different from the other channel(s).

Most likely if it is that specific channel on that specific BMS unit, then the HVC circuit is not tripping or is tripping above the level it should. IT could be a connection problem (bad solder joint, etc), or an actual wrong component installed, or a defective one.

So comparing channels is your best bet to find the issue.