I did do some searching previous to posting here and just didn't have much luck finding a similar post, so here goes...

I have an 01 A6 2.7T Q with around 130k. Just last week with a 2 month old battery after leaving the car undriven for a long weekend, I came home to find the battery completely dead. No accessories or lights were left on. I jumped the battery and it started easily. Oddly, it immediately gave me a battery warning light (first time I've ever seen that warning and I've ran previous batteries dead MANY times... No dinger to reminder me to turn off lights). Then I noticed that oddly, the volts was pegging HIGH at 16+. This happened for a minute or two and then the car "settled down" and the volts leveled off at 12 and all was good. I also noticed that curing the time the volts were pegging, numerous accessories were not available (sunroof didn't work, dash lights and dash info screen went out, radio was off, etc.). In speaking with an Audi Mechanic friend briefly, he said to check the battery, which I did at the local O'Reilly and then said the battery is perfect. He also said to put a multimeter on the batter (vehicle off) and then start pulling fuses one by one to see if I could see a jump in voltage at any fuse point - apparently this would tell me if a particular component was draining excessively. Not dice... pulled all the fuses one by one and the multimeter never budged.

So. Thoughts? This appears to have been am abrupt onslaught. The O'Reilly guy actually said that his "tool" said the alternator was in perfect working order too. Not sure how much to trust that, but I do trust those guys as much as any parts store guys. I spend a lot of time/money wit them and I believe they are shooting me straight.

Any ideas on what could be happening or at least what I should check next? I JUST checked the car after 2 hours after running and it started right up, however I suspect it will be dead by morning.

Thanks in advance, JR

 

I had a drain I could not find by pulling fuses, it turned out to be the Lojack alarm system, I unplugged it and no more troubles.

 

Well I don't have Lojack, so it's not that.

But to update, the car was surprising not completely dead this morning. Actually started, but there was a noticeable tug to get it to turnover. And once it did, same thing... the volts shot up to 16+ (though I didn't get the battery warning light)... then abruptly settled back down to around 9-9.5ish (lower than usual) and the sunroof was disabled until the volts came back up to around 10-11.

Oh and before bed last night I took a voltage reading on the battery with the car off and it registered 12.34V... this morning 11.15V. Not a HUGE dip, but a dip nonetheless.

No idea what is going on, but something is draining the battery. Any further ideas on how to track this down? I love wild-needle-in-a-haystack-goose-chases!

 

does your car have the factory alarm? I know Volvos have a big problem with the batteries in the alarms failing and causing a large drain. Going from 12.34 to 11.15 overnight is a pretty big drop. If you disconnect the battery overnight does it stay at full voltage?
(have you owned this car since new? I ask because if my sister had not told me this car had a locator type tracker in it when I bought it from her I would have never known there was one in the car, it is the sort of device that was always on and if your car got stolen you had to call in and then they would track it)
can you leave your car unlocked overnight and see you have the same voltage drop?

 

Interesting thought on the testing the voltage overnight without being connected. I'll try that tonight. According to O-Reilly (I know, I know...) it was fine and in fact performing better than new spec. But I'll try that.

And for the alarm idea... I honestly don't know. I haven't owned the car since new, but since I HAVE owned it, something has always been wrong to the point that the alarm does not work (nor the horn honk when locking doors). Was always told it was something to do with a bad door sensor or something, but as my secondary wintery/rainy day driver, I never dove into fixing it. But it's been that way for the first 3 years of ownership and as far as I can tell, nothing has changed with that that might being lending to this issue. My gut is that there is a significant drain somewhere, but I just have no idea of determining where it is.