So the wife was driving yesterday and the battery light came on. Then all sorts of electronics stopped working or acted funny. She barely made it home. Then the car died overnight. I got up this morning to look at it and there was no juice. I jumped it and it started up fine. It idles fine (about 14v). But when I rev'ed it even just a little, the battery meter spikes above 16v and the check engine light came on. Any thoughts?

 

correct me if im wrong anyone but its sounds like an alternator.
also what year/engine?

 

oh yeah, sorry. its an '01 a4 2.8l.

I just went out to check it again and the battery is down to 8v and won't start. So I'm wondering if it's the battery.

 

ya anything like that to me, sounds like an alternator.

 

I'd take it to Advance for a free charging system test - that'll tell you what part is bad.

 

Yeah, I would take it to Advance but I'm nervous to drive it anywhere. I don't want to mess anything else up with the electrical system being wacky. There's a garage right up the street that I think I'll take it to tomorrow.

Thanks for your input. I'll let you know what happens

 

classic alternator symptoms .... a little home test to do is start the car up (jump it) and disconnect the battery. If it stays running while disconnect, 9 times outta 10 its a good alternator and you'll then look at battery or a shorted wire. If it doesnt, time to replace the alternator. When you get it out, you can have it double/triple check by taking it to the autoparts store and having the alternator bench tested. If it fails, well you have the old one with you and dont have to pay a core charge

 

If it's the voltage regulator in your alternator, you could have overcharged the battery. Just a heads-up, even after you replace the alternator, you may have to get a new battery too. If you do take it in for a charging system test, they should be able to tell.