Alright I have a 92 firebird 3.1 liter, and I am having charging problems. My car runs 14.4 volts with no load, but when I use my headlights, and heater it drops to 13.0 volts. Heres the thing that confuses me, my car is fine when I am on the gas and it is moving, but if I stop at a redlight it drops. Another thing is that if I put my car in nuetral and coast at any speed and hit the brake my rpms drop about 500 for a second then go right back to normal( this only happens when I run my headlights.) Now I have had my battery and alternater tested and my battery is good, but a low charge( I figure as much, my car only gets drove 1 mile everyday to work and back and its cold where I live). My alternater was good also. Could a low charge on my battery be doing this. Is my alternater going bad but not showing up on a test yet. I'm lost I have never seen a voltage gauge do this, if anyone could help you could save me alot of money..thanks

 

I don't know about the rpm drop during braking...check for vacuum leaks and make sure the IAC valve is clean and working. As far as the alternator operation, that sounds completely normal. The more accessories it's got to power, the less you get on the gauge. Might just be not driving it enough to charge the battery fully so it's always running on the low end of it. Battery could also have a bad cell thats not holding a charge.

 

I wouldnt be really concerned right now about it. The weather can affect the battery greatly, and chances are its just that. Esp if you just noticed it doing that as it gets colder. Once the battery starts dropping to where you can barely start it if at all then I'd have to tell you its time to upgrade to one with more CCAs

Then again it could also be the gauge itself, Ive seen these third gen gauges do some weird things.