A battery pack comprising: a battery module comprising a plurality of battery units (111, 112, 113), each battery unit (111, 112, 113) being provided with respective electrode terminals (B1+,B1-, B2+,B2- B2+,B2); a control unit for providing a first configuration in which the plurality of battery units (111, 112, 113) are connected in series for discharging the battery module, and a second configuration in which the plurality of battery units (111, 112, 113) are connected in parallel for charging the battery module; a battery management device comprising: a plurality of terminal units (121d, 122d, 123d), each terminal unit (121d, 122d, 123d) comprising at least one charge terminal (CP1+,CP1-, CP2+,CP2- CP3+,CP3) connected to an electrode terminal (B1+,B1-, B2+,B2- B3+,B3) of a respective battery unit (111, 112, 113) for charging the battery module; and at least one discharge terminal (DP1+,DP1-, DP2+,DP2- DP3+,DP3) connected to an electrode terminal B1+,B1-, B2+,B2- B2+,B2)of the respective battery unit (111, 112, 113) for discharging the battery module. characterized in that the control unit comprises a plurality of discharge control terminals, each connected to a discharge terminal of a respective terminal unit of the battery management device; a charge recognition unit (TB1, TB2) for detecting a level of an electrical charging parameter, and a discharge control switch arrangement connected between discharge control terminals for switching, according to the level of the electrical charging parameter, between the first configuration and the second configuration by turning all control switches (SW1, SW2) in the discharge control switch arrangement respectively either on or off, wherein the battery units (111, 112, 113) are connected in parallel one to another through the charge terminals (CP1+, CP1-, CP2+, CP2-, CP3+, CP3-) when the battery units (111, 112, 113) are charged, or are connected in series one to another through the discharge terminals (DP1+, DP1-, DP2+, DP2-, DP3+, DP3-) when the battery units (111, 112, 113) are discharged, wherein the control unit controls the discharge control switch arrangement to switch to the first configuration when the level of the electrical charging parameter is low, and wherein when the output terminals of a charger are connected to the charge terminals (CP1+, CP1-, CP2+, CP2-, CP3+, CP3-), while the charger 200 is not being connected to an external power supply, the control unit is configured to maintain the battery units (111, 112, 113) to be connected to each other in series. a battery module comprising a plurality of battery units (111, 112, 113), each battery unit (111, 112, 113) being provided with respective electrode terminals (B1+,B1-, B2+,B2- B2+,B2); a control unit for providing a first configuration in which the plurality of battery units (111, 112, 113) are connected in series for discharging the battery module, and a second configuration in which the plurality of battery units (111, 112, 113) are connected in parallel for charging the battery module; a battery management device comprising: a plurality of terminal units (121d, 122d, 123d), each terminal unit (121d, 122d, 123d) comprising at least one charge terminal (CP1+,CP1-, CP2+,CP2- CP3+,CP3) connected to an electrode terminal (B1+,B1-, B2+,B2- B3+,B3) of a respective battery unit (111, 112, 113) for charging the battery module; and at least one discharge terminal (DP1+,DP1-, DP2+,DP2- DP3+,DP3) connected to an electrode terminal B1+,B1-, B2+,B2- B2+,B2)of the respective battery unit (111, 112, 113) for discharging the battery module. a plurality of discharge control terminals, each connected to a discharge terminal of a respective terminal unit of the battery management device; a charge recognition unit (TB1, TB2) for detecting a level of an electrical charging parameter, and a discharge control switch arrangement connected between discharge control terminals for switching, according to the level of the electrical charging parameter, between the first configuration and the second configuration by turning all control switches (SW1, SW2) in the discharge control switch arrangement respectively either on or off, wherein the battery units (111, 112, 113) are connected in parallel one to another through the charge terminals (CP1+, CP1-, CP2+, CP2-, CP3+, CP3-) when the battery units (111, 112, 113) are charged, or are connected in series one to another through the discharge terminals (DP1+, DP1-, DP2+, DP2-, DP3+, DP3-) when the battery units (111, 112, 113) are discharged, wherein the control unit controls the discharge control switch arrangement to switch to the first configuration when the level of the electrical charging parameter is low, and wherein when the output terminals of a charger are connected to the charge terminals (CP1+, CP1-, CP2+, CP2-, CP3+, CP3-), while the charger 200 is not being connected to an external power supply, the control unit is configured to maintain the battery units (111, 112, 113) to be connected to each other in series.