A method and an apparatus, according to an exemplary aspect of the present disclosure includes, among other things, a high voltage battery pack comprised of a least a first module comprised of a plurality of first battery cells, a second module comprised of a plurality of second battery cells, and a third module comprised of a plurality of third battery cells. A first passive battery management system monitors and balances the plurality of first battery cells, a second passive battery management system monitors and balances the plurality of second battery cells, and a third passive battery management system monitors and balances the plurality of third battery cells. A pack manager measures a voltage of each of the first, second, and third modules, compares measured voltages of the first, second, and third modules, and actively balances a lower charged module from the first, second, and third modules with energy from a higher charged module of the first, second, and third modules.