The active balance can transfer energy from the high voltage/capacity cells to low voltage/
capacity cells, the aim is to extend the life span of the full pack. The active balance can be
happened both in charging or discharging. See sketch map as below:
Active balance charging
Active balance discharging
The active balance circuits are typically based on capacitors, inductors, transformers, power electronics interface and so on... Which cost high and have big sizes, that’s why it is not recommended in small packs that be made within one hundred cells.