I have a 96 Camaro and started having a problem a couple of weeks ago with the Battery gauge. When I start it up everything is normal. But after driving it a while the battery gauge is down in the red. Now most times after a few minutes it pops back up to normal. I've already replaced the battery which didn't help. Hate to think it's the alternator as I replaced it about 5 years ago. Certainly they will last longer than that. And I would think if it was the alternator the battery would drain and not recover. And I've also noticed that if I stop like at the grocery store and it is in the red when I come back out and start it up everything is normal again....

Anyone out there have any suggestions. Hate to spend the money on a new alternator and still have the problem...

Thanks

Gary

 

Well, it may be any of those things, or even a combination. Even the gauge may be faulty. Either way, begin with the easiest tests first. Get your hands on a simple digital voltmeter. Set it on DC 20V. Take the leads and check the charge of the battery after the car has been off for perhaps 30 minutes. It should register at right around 12volts. Now, leave the leads and secure them to the battery posts (you can also place the negative lead on a good ground source and the positive lead on the auxilary positive post, located by the engine bay fuse block). Start the car with the leads secure and monitor the voltage. The alternator should be charging the battery to roughly 13.5 to 14.6V. Any less and the alternator is undercharging. If it shows a value of less than 13.5, try turning on as many accessories as you can, i.e headlights, rear defrost, interior lights, radio, wipers, etc., and then monitor the current flow. If you notice it steadily dropping, I'd be willing to be the alternator needs replacing. If you do, however, perform these tests and get positive results, you may have a faulty gauge/wiring to the gauge. That would require some wire tracing. I'd even go as far as installing a standalone voltage indicator gauge and not rely on the faulty one if that's the case.

Good luck, and let me know what you find out.

 

Thanks for the quick response. Actually my brother-in-law did hook up a voltage meter. The battery showed 12.2 with the car off. Then it went to 14.4 with the car running. He then unplugged the ground plug from the alternator and it went back to 12.2 then back to normal when it was plugged back in. Then all of a sudden it dropped without us doing anything. But right before that we had something click. Never could figure that out. He checked the alternator and it was not putting anything out. Then another click and it was working again...

And I can also tell you that the gauge is fine. When I drive home from work at night as soon as the gauge goes down the headlights and the dash lights both dim!!!!!

Gary

 

Also be sure you have a good serpentine belt -- which drives the alternator...