Abstract: A system and method for balancing the voltages between a plurality of battery packs while charging the battery packs. A processing circuit detects the respective voltages across the battery packs and the amount of energy used by a DC load. The processing circuit configures DC-DC converters to draw energy from the battery packs to provide energy to a DC load. The processing circuit configures DC-DC converters to draw more energy from the battery pack having the higher voltage than from the other battery packs to provide the energy to the DC load. Drawing a higher amount of energy from the battery pack having the higher voltage causes the voltage difference between the battery packs to decrease until the voltages across the battery packs are about equal.