a method and apparatus provides supplemental power to an engine . the method and apparatus includes a pair of conductive leads for connecting the supplemental power to an engine electrical system , one or more batteries connected in parallel with one or more capacitors , a relay connected to the conductive leads , a shunt cable connecting the batteries and capacitors to the relay and a processor for controlling the relay to selectively apply electrical power to the engine electrical system . the method and apparatus includes safety features to reduce the risk of injury to the operator and damage to the apparatus and / or engine electrical system .