Patent ID: 8643334

Claim:
A battery balancing circuit for balancing the voltages of a detachable battery apparatus and a reference battery module, wherein the detachable battery apparatus and the reference battery module are connected in parallel, and the detachable battery apparatus, which can be added to and detached from the battery balancing circuit in a non-destructive way, is a detachable apparatus including a battery module or a detachable battery module, the battery balancing circuit comprising: a load channel connected to the reference battery module and connected to the detachable battery apparatus through a first switch; a charging-discharging channel disconnected from the reference battery module but connected to the detachable battery apparatus through a second switch; a micro control unit, connected to the reference and detachable battery module, for accessing information of the reference battery module and the detachable battery apparatus and obtaining a threshold value according to the voltage of the reference battery module; and an charging-discharging control circuit connected to the reference battery module thorough the load channel, wherein when the voltage of the detachable battery apparatus is higher or lower than the threshold value, the micro control unit controls the first and second switches to ensure that the detachable battery apparatus is disconnected from the load channel but connected to the charging-discharging control circuit through the charging-discharging channel, and the micro control unit further makes the reference battery module charge the detachable battery apparatus or makes the detachable battery discharge to the reference battery module.