QuikPup

Ok so I just got this car after it sat for a year or more in a field.... The first time I started it, it was charging just fine. Shut it off went to the gas station filled up a gas can came back put it in and started it again. This time it was not charging (battery dead & probably junk from sitting) it dies as soon as I tried to move the car. I then again jump started it and it was fine and then I drove it about 100mi to my house with no problems. When I pulled in my yard it stopped charging again but the battery had taken enough charge by now that I could shut the car off and restart it. Once restated it would charge for no more than 1 minute and stop again. Now even if I start the car with a good battery installed it will stay running but only because the battery is good, the alternator is not charging at all. Should I just assume its a bad alternator and buy one or could it be something else? Thanks again guys I'm still new at this Audi stuff

4Driver4

Most like worn brushes in the alternator. You can try replacing the brushes, but it's probably a better idea to replace the alternator. Buy a good alternator or have yours rebuilt. Do not use an Autozone alternator.

SloopJohnB@mac.com

How many miles on the car? If less than about 200K miles the alternator should be ok unless a diode failed or much less likely a brush broke. Sitting for a year shouldn't affect the alternator.

There are diagnostic tools that can evaluate the alternator, even a waveform analysis should let you know if you're getting partial rectification (bad diode). One thing you must use is a multimeter and it should read about 13.2-13.8v.

It could also be dirty connections at the battery or ground(s).

4Driver4

Alternator failure can happen at any time. Of the three 30v Audi's I support, one died at 175k, one died at 85k, and one is fine at 177K.

QuikPup

The car has 94k miles on it. According to the voltage gauge on the dash it is below 12v when not working and about 14 when it was working on the drive home.