Now I have this problem where my gauge shows about 12.4-12.8, and an AUTOXRAY shows about the same. I think that is a little low. But when I use my multimeter on my battery it reads 13.8-13.9, alternator is 14. That seems right. What are some other areas to check? I have a new alternator and battery, no corrosion on the cables, anything like that. The car drives fine (lights aren't dim or anything) no problems at all there, but seeing this on the gauge is really starting to bother me, any ideas? Or is it just crappy GM gauges.

 

Yo I got almost the same problem as you. But I have a 1600 watt system in my car, and A LOT of accessories that take power. So when im driving my batt gauge is like halfway, when im at idle its at the top the bottom red line like at 8 little higher than it, till i give it gas it rises. And I have an OPTIMA Red Top battery. So my lights dim when its idle then they get brigter when i rev it, its kinda funnny. Not much you can do.

 

I just checked the ripple voltage on the alternator, and it is coming in around .043-.044. I'm not sure if that has anything to do with what I'm having a problem with. Also, how does GM get the reading for the gauge, is it the connector on the alternator or some other sensor?