A battery management system for a vehicle, comprising: a first battery module having a first plurality of battery cells (1 - 24); a second battery module having a second plurality of battery cells (25 - 48); and a bi-directional balancing circuit (500, 502, 504, 506, 512, 514, 516, 518) electrically connected to at least one battery cell of the first plurality of battery cells (1 - 24) and at least one battery cell of the second plurality of battery cells (25 - 48), wherein the bi-directional balancing circuit (500, 502, 504, 506, 512, 514, 516, 518) is configured to transfer charge between the at least one battery cell of the first plurality of battery cells (1 - 24) and the at least one battery cell of the second plurality of battery cells (25 - 48), wherein the first plurality of battery cells (1 - 24), includes a first battery cell and a second battery cell; the second plurality of battery cells, including a third battery cell and a fourth battery cell; and the bi-directional balancing circuit (500, 502, 504, 506, 512, 514, 516, 518) is electrically connected to both the first battery cell and the third battery cell, wherein the bi-directional balancing circuit (500, 502, 504, 506, 512, 514, 516, 518) is further configured to transfer charge between at least the first battery cell and the third battery cell, wherein the bi-directional balancing circuit (500, 502, 504, 506, 512, 514, 516, 518) comprises one balancing circuit being an integrated circuit and being configured to transfer charge between the at least one battery cell of the first plurality of battery cells (1 - 24), and a further balancing circuit being an integrated circuit and being configured to transfer charge between the at least one battery cell of the second plurality of battery cells (25 - 48), wherein the one balancing circuit comprises a first converter and the further balancing circuit comprises a second converter, wherein the first and second converters are respective buck -boost converters which are connected with each other through a bus bar and are adapted to increase or decrease the voltage between the first battery cell and the bus bar, and configured to transfer charge between at least the first battery cell and the third battery cell, wherein the first converter increases the voltage output to the bus bar and wherein the second converter decreases the voltage from the bus bar, wherein the battery management system is further configured that the energy from the bus bar is further transmitted to other components within the vehicle that use voltage power supplies. a first battery module having a first plurality of battery cells (1 - 24); a second battery module having a second plurality of battery cells (25 - 48); and a bi-directional balancing circuit (500, 502, 504, 506, 512, 514, 516, 518) electrically connected to at least one battery cell of the first plurality of battery cells (1 - 24) and at least one battery cell of the second plurality of battery cells (25 - 48), wherein the bi-directional balancing circuit (500, 502, 504, 506, 512, 514, 516, 518) is configured to transfer charge between the at least one battery cell of the first plurality of battery cells (1 - 24) and the at least one battery cell of the second plurality of battery cells (25 - 48), wherein the first plurality of battery cells (1 - 24), includes a first battery cell and a second battery cell; the second plurality of battery cells, including a third battery cell and a fourth battery cell; and the bi-directional balancing circuit (500, 502, 504, 506, 512, 514, 516, 518) is electrically connected to both the first battery cell and the third battery cell, wherein the bi-directional balancing circuit (500, 502, 504, 506, 512, 514, 516, 518) is further configured to transfer charge between at least the first battery cell and the third battery cell, wherein the bi-directional balancing circuit (500, 502, 504, 506, 512, 514, 516, 518) comprises one balancing circuit being an integrated circuit and being configured to transfer charge between the at least one battery cell of the first plurality of battery cells (1 - 24), and a further balancing circuit being an integrated circuit and being configured to transfer charge between the at least one battery cell of the second plurality of battery cells (25 - 48), wherein the one balancing circuit comprises a first converter and the further balancing circuit comprises a second converter, wherein the first and second converters are respective buck -boost converters which are connected with each other through a bus bar and are adapted to increase or decrease the voltage between the first battery cell and the bus bar, and configured to transfer charge between at least the first battery cell and the third battery cell, wherein the first converter increases the voltage output to the bus bar and wherein the second converter decreases the voltage from the bus bar, wherein the battery management system is further configured that the energy from the bus bar is further transmitted to other components within the vehicle that use voltage power supplies.