An electric powertrain includes an electric machine, an inverter connected to the electric machine, and an energy storage system for providing an electric current. The energy storage system includes a first energy storage device operable at a first device voltage, and a second energy storage device operable at a second device voltage. A plurality of low-loss switching devices interconnect the first energy storage device and the second energy storage device. The switching devices are selectively controllable between a first operating mode for providing the electric current at a first system voltage, and a second operating mode for providing the electric current at a second system voltage. The first system voltage is different from the second system voltage.