Abstract: The present disclosure discloses a smart battery, an electric energy allocation bus system, a battery charging and discharging method and an electric energy allocation method. The smart battery internally comprises a battery body portion and a control unit. The smart battery can collect various data of the battery, can be communicated with other smart batteries in a battery pack of a same group and a battery pack control system, and can realize electric quantity transfer among smart batteries of the same group through the electric quantity allocation bus, and realize electric quantity transfer among some batteries of a battery pack accessed to the electric energy allocation bus. Besides, controllable processes of charging and discharging, that is, active balanced charging and discharging, can be realized.