To provide a battery management system of a discharging system and the method thereof.

A monitor unit monitors a plurality of battery cells. When potential, current, or temperature of any of the battery cells is changed, a control unit controls a plurality of energy storage units of an isolation type, charges a battery pack, discharges at least one of the battery cells of a relatively high potential, achieves equalization of the potential of the whole battery pack, thereby improving energy conversion efficiency in an apparatus.