Electrical battery drain fault
#1
10-08-2014, 11:36 AM
Electrical battery drain fault
Hi folks
A problem I’ve had with my C6 since I bought it two years ago is an intermittent battery drain which I’ve tried all sorts to trace. It’s getting steadily worse and none of the ‘standard’ techniques have traced it yet.
The dealership I bought it from replaced the battery after reading battery issues on the log but that was a ‘get it out the door’ fix. Subsequent log reads mention battery but nothing else. Often the car will sit for a week staying at 100% then hours later it’s at 10% before the auto shutdown arrests the drain by selectively shutting stuff down (I think) allowing it to always start.
Today was different though. It was 100% this morning then 50% by lunchtime, went to start it and …. nothing. All the indications looked normal but the starter didn’t turn. Tried a couple of more times before leaving the ignition on for a think. In front of my eyes the 50% charge reduced to 10% in 60 seconds – some drain for a battery of that size I’d hazard a guess! After a couple more tries it started and the battery charged slowly as normal. I had to be somewhere so didn’t get chance to apply gloved hands to cables to check for excess heating but that’s gotta be starter circuit or something big surely – any thoughts?
2007 Avant S-Line Quattro
A problem I’ve had with my C6 since I bought it two years ago is an intermittent battery drain which I’ve tried all sorts to trace. It’s getting steadily worse and none of the ‘standard’ techniques have traced it yet.
The dealership I bought it from replaced the battery after reading battery issues on the log but that was a ‘get it out the door’ fix. Subsequent log reads mention battery but nothing else. Often the car will sit for a week staying at 100% then hours later it’s at 10% before the auto shutdown arrests the drain by selectively shutting stuff down (I think) allowing it to always start.
Today was different though. It was 100% this morning then 50% by lunchtime, went to start it and …. nothing. All the indications looked normal but the starter didn’t turn. Tried a couple of more times before leaving the ignition on for a think. In front of my eyes the 50% charge reduced to 10% in 60 seconds – some drain for a battery of that size I’d hazard a guess! After a couple more tries it started and the battery charged slowly as normal. I had to be somewhere so didn’t get chance to apply gloved hands to cables to check for excess heating but that’s gotta be starter circuit or something big surely – any thoughts?
2007 Avant S-Line Quattro
#2
10-08-2014, 02:27 PM
A few more details:
Car is stock, nothing changed at all. Battery was changed by PO for same snag I think but not checked recently so needs looked at I guess as a possible culprit. For the amount of grief it's had I can't believe it's still going!!
Check of current draw across the fuses is a tough one - the fault is so intermittent I could be there forever but it's next on list.
The Avant water ingress recall was done but I stripped it all out myself & dry as a bone with no water marks.
Car is stock, nothing changed at all. Battery was changed by PO for same snag I think but not checked recently so needs looked at I guess as a possible culprit. For the amount of grief it's had I can't believe it's still going!!
Check of current draw across the fuses is a tough one - the fault is so intermittent I could be there forever but it's next on list.
The Avant water ingress recall was done but I stripped it all out myself & dry as a bone with no water marks.
#3
03-06-2015, 05:15 AM
Latest update folks - Audi had the car for three days and tried to charge me £500 (another story) to find nothing. I'm now suspecting the meter that measures the battery voltage but no idea where such a device is on the car - any clues?
#4
03-09-2015, 04:20 PM
It looks like you're in the UK. If you were in US, I would suggest hitting an auto parts store like Autozone that performs free battery and alternator testing. Maybe there is a outfit like that near you. Secondly, if your car does not have a voltimeter, they make relatively inexpensive ones that plug into the cigar lighter. I just ordered some (they are Chinese-made) for about US$8 each. Intermittent is a bitch, but it has to be something pretty sizeable to deplete a battery that quickly. That's assuming that the meter is reading correctly. I suspect a short in a wire that has rubbed bare and occasionally makes contact with metal, but no good idea for locating it. If it was a constant drain, then pulling and replacing fuses one by one might isolate it. Good luck, mate.
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