Systems and methods of controlling an uninterruptible power supply are provided. In one aspect, an uninterruptible power supply includes a first input configured to receive input power from a first power source, a second input configured to receive input power from a second power source, an output configured to provide output power to a load derived from power from at least one of the first power source and the second power source, a power conversion circuit coupled with the first input, the second input and the output, and a controller coupled with the power conversion circuit. The controller is configured to control the power conversion circuit to provide an output voltage of the output power at a first voltage level, and to control the power conversion circuit to provide an output voltage of the output power at substantially a second voltage level.