A charging system has a battery pack and a charging device. The battery pack has a battery cell and a plurality of identifiers that identify a configuration of the battery cell. The charging device has a charging unit, a signal transmission unit, a reading unit, and a control unit. The charging unit charges the battery pack. The signal transmission unit transmits a first signal and a second signal to the battery pack separately to read the plurality of identifiers when the battery pack is attached to the charging unit. The reading unit reads the plurality of identifiers according to the first and second signals to determine the configuration of the battery cell. The control unit controls the charging unit according to the configuration of the battery cell.