My friend and I are trying to build a very basic to get a spark plug to fire. Right now we have a plug, and Ignition coil that outputs 20 kV. The Ignition coil says on it 12 V and was bought at an auto parts store so im assuming its an ignition coil for a car. What kind of battery should we test it with? Do we need as much power as a car battery or can we live with a much smaller size? Also i heard about using a capacitor to absorb the back emf in the primary coil that will run across the switch normally. i was thinking maybe a high voltage capacitor of like 10-100 microfarads?