A variable speed air compressing system includes a compressor, a motor configured to actuate the compressor, and a rectifier configured to receive alternating current from a first power source and to provide rectified direct current having a first voltage. The system also includes an inverter configured to receive the rectified direct current and to receive direct current from a second power source having a second voltage. The inverter is configured to provide alternating current to the motor. The alternating current provided to the motor is based on the rectified direct current if the first voltage is greater than the second voltage and the alternating current is based on the direct current from the second power source if the second voltage is greater than the first voltage.