Patent ID: 8299758

Claim:
A charging controller connected to one or more secondary cells and detachably connected to a charger or a cell driver, each of the charger and the cell driver having a control power supply circuit supplying a control power to the charging controller, the charging controller comprising: a charging amount control circuit detecting a cell voltage of each secondary cell; comparing the detected cell voltage with a predetermined target voltage; and outputting a charging control signal for instructing the charger to reduce a charging current when the detected cell voltage exceeds the target voltage; and a protection circuit detecting a cell voltage of each secondary cell; comparing the detected cell voltage with a predetermined upper limit voltage higher than the target voltage; and cutting off a current path from the charger to the secondary cell when the detected cell voltage exceeds the upper limit voltage, wherein both of the protection circuit and the charging amount control circuit operate by using the control power as a power source while the control power is supplied to the charging controller.