This document has been declared "Stabilized" and will no longer be subjected to periodic reviews for currency. Users are responsible for verifying references and continued suitability or technical requirements. New technology may exist.The scope of this SAE Information Report is to acquaint and inform those concerned with cold weather operation of diesel powered machines and vehicles with the selection and application of electrically powered starting aids currently available. It deals specifically with the design, function, and application of line voltage electrically powered engine preheaters and battery warmers.