An electric supply system for a vehicle system includes two or more electric energy storage devices. Two or more buses each conductively couple an energy storage device with a corresponding load of plural loads. A controller controls conduction of current from one or more of the energy storage devices to one or more other buses to transfer energy to other energy storage devices or other loads. A method includes directing a first energy storage device of a first power supply assembly to supply electric current to a first bus conductively coupling the first energy storage device to one or more first loads onboard the vehicle system. The method further includes conducting the electric current from the first energy storage device to one or more second buses of one or more second power supply assemblies to recharge one or more second energy storage devices or power one or more second loads.