Doubts with ammeter.

[JUANRAF]

Hi,

My ammeter shows discharge (negative zone) when I turn on the car light while driving.
is this correct?
Thanks

[Steve Simmons]

Yes and no. If the voltage / current being used by the lights exceeds the output of the generator then it will show a discharge. So it kind of depends on how powerful your bulbs are. Also, the condition of the generator, control box and wiring will play a part in how much electricity the charging system can offer the battery. If the control box is not clean and properly calibrated, then that will also make a notable difference. I have halogen bulbs, which are a little more efficient than the stock incandescent bulbs, and my ammeter stays right around zero when the lights are on unless the RPMs are very low, such as siting at a traffic light.

Long story short, it sounds like the ammeter is working properly.