EG4 12v life power 4 v2 cell 4 overvolt issue

[jwe42]

Hi I have an issue with 3 of my 4 batteries. All works well until I need to charge them. 3 of the batteries go into protect mode and shut off for a cell 4 overvolt after reaching 100%. One did this right out of the box the second and third failed after about 90 days the last is still operating as normal. If I shut off the charger and let them sit for a while I can discharge them normally but upon recharging, they fail again. 1) Has anyone else had this issue? 2) any advice or solutions? The vendor/distributor has been less than any help.
Thanks in advance for your help.

 

[BentleyJ]

Sounds like they need to be top balanced. What is your charging voltage?

 

[jwe42]

14.2V as indicated on the battery.

 

[GXMnow]

Set it down to 13.8 volts, and let it sit in absorb for a while, the internal BMS should "SLOWLY" balance the cells. 13.8 is still over 95% charge, so if it does not shut down at that level, you can just use them a little lower. 14.2 would be 3.55 volts per cell which is good, but it only takes a tiny imbalance for one cell to hit 3.65 and shut down while the rest of the cells are not over 3.5 volts yet. Can you monitor the cell voltages easily? Can you get to the cell terminals? You may be able to speed things up if you can connect a load on just the high cell so the others can charge without that high cell going to protect. A car headlight at 3.55 volts pulls about 2 amps. Se the charger at 2 amps or less at 13.8 volts until the other cells catch the voltage of the high one with the lightbulb on it. As you get close, you may find a different cell may take off. At that point, you may need to find another light bulb, or just lower the charge current to give the BMS more time to balance at it's low current.