A power controller includes at least a first and a second power supply each having a positive and a negative output terminal. A voltage measuring circuit is coupled to the positive and negative output terminals of at least one of the power supplies. A main switching element is coupled between the negative output terminal of the first power supply and the positive output terminal of the second power supply. The positive output terminal of the first power supply and the negative output terminal of the second power supply are connected to an electrical load. A pair of diodes is serially connected across the electrical load. The voltage measuring circuit is configured to close the main switching element when a measured voltage exceeds a selected threshold such that the first power supply and the second power supply are connected to the electrical load in parallel when the main switching element is closed.