A method and apparatus are disclosed for a Battery Management System (BMS) for the controlling of the charging and discharging of a plurality of battery cell (12). Each battery cell has an associated plurality of control circuits (32, 36) which monitor and control the charging of individual battery cells. These units are controlled by a central microcontroller (14) which shunts current around the battery cell if fully charged and stops discharge if a battery cell is fully discharged in order to prevent damage to the other cells.