A battery charging system is disclosed. The battery charging system includes a battery cell, a voltage measurement circuit and an overvoltage protection circuit. The voltage measurement circuit measures a cell voltage of the battery cell. The overvoltage protection circuit is configured to stop charging the battery cell when a reading voltage measured by the voltage measurement circuit reaches an overvoltage setting value. The battery charging system also includes a battery charger for charging the battery cell, and a control unit for supplying a control voltage to the battery charger to perform feedback control of an output voltage of the battery charger. The battery charger includes a voltage feedback input for receiving a feedback voltage and a setting value input for receiving a setting voltage. The control voltage is generated based on the reading voltage and the setting voltage.