I have no expertise in this: but it could be one of the cells in the battery is performing worse than the rest. The way charging works in a pack is that it meas

I have no expertise in this: but it could be one of the cells in the battery is performing worse than the rest. The way charging works in a pack is that it measures all 4 cells for instance, and if one is higher than the others it discharges that one only, then continues on charging them all at once, then periodically checks again