LOL on the extention cord. Best bet would be a yellow top optima battery and a capacitor to run between your amp and battery. A capacitor basically holds a charge like a second battery. It basically works to keep your huge amp from having such a drain on your battery so your battery can run the rest of your car. By no means am I a car audio expert(big stereos just add weight), but that's the way it was explained to me in layman's terms.