adding a charging fault light

Yep everything i have seen and read about so far shows the light circuit to be an indicator only, and not part of the exciter. Its gonna be awhile before i get to test this. Now if thats not true, i can always put a lightbulb or a small resistor in parallel in the circuit to get it to do what its supposed to do. Anybody hazard a guess what ohm resistance resistor i would need?

Matt