A method of balancing current in a vehicle electric system having a system bus, a first battery, a first bi-directional battery voltage converter selectively transferring a first current between the first battery and the system bus, a second battery, a second bi-directional battery voltage converter selectively transferring a second current between the second battery and the system bus, and a controller controlling the first bi-directional battery voltage converter and the second bi-directional battery voltage converter. The method includes sensing the first current and sensing the second current. The first bi-directional battery voltage converter and the second bi-directional battery voltage converter are controlled so that the first current and the second current are equal portions of a load current supplied to an electrical load connected to the system bus.