I just bought a 2004 A6 (2.7T) about a month ago. When the car is on but the engine isn't running the battery drains very quickly, in under 10 minutes.
I don't have subwoofers or any aftermarket things done to it that would be draining it. Also when it's left outside on cold nights it wont start in the morning. When I jump the battery it starts up immediately with no problems.

The battery is less than 2 months old, it was replaced just before I bought the car.

Has anyone else had this problem, or have any ideas on how to troubleshoot the problem? If it's possible for me to fix this myself I would rather do that than bring into a shop and spend money to fix it that could otherwise be going to an intake/exhaust/tune and all that good stuff...

 

Take the car to AutoZone or equivelent and have them test the battery. Just because it is new doesn't mean it is any good.

 

After testing the battery to be sure it's good at a parts place or use your load tester if you have one, the way to test for drain is to pull the positive cable off the battery and put a DC ammeter between the battery and the cable. With the car off, it should measure about 50 mA. If it's more you have excessive drain. To find it, just start pulling fuses until you see the meter drop, that will the be the draining circuit. Just trace it from there. The most common drain is a trunk or glovebox lamp staying on.

 

Good advice on how to trace a battery drain, but he says it drains in 10 minutes. He would have to have one hell of a light in that trunk! Is he growing, ummm, medicinal herbs there? Is he running a tanning booth there?

The only electrical system that will kill a battery in 10 minutes is the starter.

Hence, my guess (and it IS just a guess!) of a bad battery.

But, still, I liked your advice!

 

Alright, I guess I'll be taking it in this weekend then. Thanks for the help guys