Cell Balancing

It prevents weak cells limiting capacity. It often happens at high charge. Passive and active methods exist. Passive balancing burns off a small amount of energy from the fullest cells as heat, while active balancing moves energy to weaker cells. Balancing usually happens when the battery is near full and the car is plugged in. Severe imbalance can reduce range and trigger warnings.

The BMS bleeds or transfers charge.

Occasional full charges may help balancing. Follow manufacturer advice.