Battery won't charge :( Half of cells low voltage


I was just wondering if anyone has any clue how to revive this battery? It’s from an iWonder SK-A2 / Slick Revolution Min-Eboard, which says ‘21.6VDC 8.8ah’ on the battery label. It’s not been used for a while so I was worried it had not been cycled enough.

The charger stays on green and won’t go to red. I’ve stripped down the battery and have tested the individual cells. Half of them appear to be up to voltage and the other half aren’t (the ones with back dots on, including the ones in the row behind those). Does this mean dead cells or a faulty BMS? Any help would be much appreciated.

Many thanks.

The BMS will generally prevent a battery from charging if cells are not in the correct voltage range, so in your case you probably need to try a different method to charge each cell to get them back in the safe range.