BATTERY PACK

PROBLEM TO BE SOLVED: To provide a battery pack capable of executing highly accurate charging/discharging control even when five or more secondary battery cells are connected in series, and reducing power consumption of a circuit. SOLUTION: The battery pack has a combined battery group 1 in which combined batteries 1-1, 1-2 consisting of battery cells BAT1-BAT4 and BAT5-BAT8 are connected in series; and a power supply terminal unit and a signal terminal unit 2 to be detachably attached on a charger or a load body. The battery pack is provided with a power supply activating circuit 8 and power supplying circuits 9-1, 9-2 to be activated based on an activation signal to be supplied from the charger or the load body when the charger or the load body is attached, and the power activation circuit 8 and the power supply circuits 9-1, 9-2 are activated, thereby battery voltage is supplied from each of the combined batteries 1-1, 1-2 to each of charging control signal conversion circuits 4-1, 4-2, a charging control signal logical OR circuit 6, discharging control signal conversion circuits 5-1, 5-2 and a discharging control signal logical OR circuit 7. COPYRIGHT: (C)2008,JPO&INPIT