An intelligent auxiliary power supply system for supplying power to a load such as a furnace or air handler using a rechargeable power source. An intelligent controller determines appropriate periods for switching to auxiliary power, thus allowing the user to realize increased energy related cost savings. A plurality of sensors including a current transducer, an indoor and outdoor temperature sensor, and a clock transmit information to the intelligent controller. Implementing user configured algorithms, the intelligent controller continuously compares information transmitted from said sensors and said load, to information inputted by the user via an electronic device to determine the appropriate power configuration. A remote electronic device may also be connected to the system, allowing the user to control the system while not in close proximity to said system and also allowing the user's energy provider to send requests to switch to auxiliary power.