BH, That's what you need, some old puffed out Rex batteries works well. These were some 16c's that I didn't have much use for. The charge does hold up well so it's one less thing you have to charge everytime you go to the field. It's cranked over a 40cc gasser with no problems before. I came to this just because none of the 12v hobby batteries put out enough amps to start anything. That Mavrikk starter that they claim will start a .90, they left out the part of it will only start it once and toast the batteries doing it.