Hi Roger, The jack is like the one used with transmitter charging jacks only three sizes larger. Radio Shack I believe still has them in those parts drawers. Make all wires thick and short. A very small voltage drop is a big deal with 1.5 volts! My starter battery is 8 700 ma nicads all wired in parallel. At Toledo I bought 3 3700 ma nicads to wire in parallel when my octet fades. When you bench run your engine do great experimentation with tuning and quick throttle changes and study how well the engine runs at all throttle settings to insure you have a well tuned engine. This does require a good ear for engine operation....On my older Seidel evo engines; they where quitting at half throttle because the midrange would go lean at that throttle setting if the idle mixture was set to run idle correctly so I had to have a bit rich idle for the midrange to be ok. The newer carbs might have solved this issue.-Tom