Patent ID: 7145788

Claim:
An electrical power system for use in a vehicle that includes an engine equipped with a starter motor and an alternator for supplying electrical current while the vehicle engine is in operation, said electrical power system being operable for supplying power to equipment that is contained in the vehicle and that requires power during periods of time during which the vehicle engine is shut down, said electrical power system comprising: an insulated enclosure; a set of one or more batteries contained within said insulated enclosure; an electrical heating element contained within said insulated enclosure for maintaining the temperature of said set of batteries at or near a predetermined temperature while the vehicle engine is in operation; and circuitry for sensing the temperature of said set of batteries and for selectively supplying electrical power from the alternator of the vehicle to said electrical heating element when the vehicle engine is in operation, said circuitry supplying said electrical power from the vehicle alternator when the temperature of said set of batteries is below said predetermined temperature and interrupting the supply of electrical power from the vehicle alternator when the temperature of said set of batteries reaches said predetermined temperature.