A method for controlling at least one load connected to a primary and a backup power supply having sensor for sensing a voltage on the primary power supply with a first voltage sensor; sensor for sensing a voltage on the backup power supply with a second voltage sensor and implementing a control algorithm in a controller to augment power from said primary power supply with power from the backup power supply in response to an input from the first and second voltage sensors and an input from at least one external sensor wherein the algorithm controls a switch between the at least one load and the primary and backup power supplies.