Hey guys I have a problem with my charging system I think. When I'm at a light my amp needle goes way down past the middle mark. This only happens when I have my lights on and at idle. The battery is new te 105 amp alternator is fairly new. Is this a faulty ground somewhere or what?

'89 IROC L98

 

It's normal. As long as it is out of the red zone, you are OK. That's why there is such a large swing with the guage. At idle with accessories on there are times when the alt actually turns itself off. Thats because the electrical demands of the car cannot be met with the alt without overheating it. Remember also, at idle rpm in drive if it's an automatic a 105 amp alt only has maybe 15-20 amps output if that. I have an 89 also with a 140 amp unit, it does the same thing. The CS-130 alt suffered from overheating problems so the regulator is designed to throttle it way back at very low rpm with high load on the system. The newer "D" version has a different charging curve and is not so likely to overheat like the straight 130. There is a myth that the alt meets all the demands of the cars electrical load, it is simply not true. The battery supplies the bulk of the current and the alt will only maintain the battery to approx 75% or so of rated capacity.

 

Hey great info on the Alt and stuff. I took my battery out and put it on a slow tricle charge for a few hours. Automatic shuts off and then I found out my battery ground was loose at the motor and the terminal also needed a couple turns. I put the battery back in fired her up and went for test drive. Headlights heater and defroster all worked great. No dimming at a stop and no gauge problem. Maybe later once the battery gets a little more drained.

Thanks for that info I totally agree with you.

Have a Happy New year!