A single nicad does not put out more than 1.2 volts. There are "hot" plugs and "cold" plugs, and some light up at 2 amps where others light up at 4 amps, and without on board glow, some fail due to overheat and/or vibration. I understand that some 2 cycle engines really run hot.

AWG 20 wire gauge is adequate to conduct up to 5 amps; thinner wire has more resistance and could cause the plug to NOT light up.

My post above is from my experience. I have tried on board glow with throttle operated switch and servo operated switch, but those are different stories.

I would be interested in your problem for my information, and would be glad to offer help if I can. I would like to know what brand engine and size, what brand/type glow plug, and % nitro in fuel.

feihu