Hey everyone. I have a 2002 A6 4.2, and when i let is sit for 24 hours, it cranks a little slower than usual. After 48 hours, it cranks very slowly, and 72 hours later it may not even start (solenoid clicks). Here's what I have done tried:

Took the car to advance auto and they tested the battery. 588 Amps and and I don't remember what they said for voltage, but they said that the battery was good.

To double check, i disconnected the battery cables for 72 hours, and reconnected them. the car started perfectly normal after that 72 hour period.

I figured it must be a parasitic draw, so I tested for that using an ammeter. Hooked it up it up between the negative terminal and the negative cable. After 15 seconds or so, the reading drops to 66mA. I disconnected my aftermarket rca adapter for the stereo, and it drops to 48mA. Neither of these readings seem like a serious parasitic draw though.

if I drive the car daily, there is no problem. Alternator shows just above 14V on the dash gauges. So I would say the alternator is not the problem since it does fine if driven daily.

Any ideas?

 

Sounds like something is loose...check the alternator connections.

 

Them damn parasite will get you every time.

Look for a light left on - trunk, motor, glove box etc.

If that dosen't work try removing one fuse at a time overnight

 

Thanks for the replies. I'll try out both answers. All fuses one at a time could take over a month, but I think I can do half of them, then half of the 'offending' group repeatedly till I get down to the offending fuse. It just concerns me that my draw was so low.

Not sure if this helps, but you mentioned the trunk and it made me think. My trunk doesn't lock any more, makes a noise, but no lock (I can still open it with the outside handle, but the alarm will go off). Maybe related? Both issues may have started around the same time, but I'm not completely sure. I don't often try to enter my trunk with the car locked, so they may be very different occurrences chronologically.

Thanks again, I will post back my solution when I find it.

 

Do like you were doing measuring the drain while someone else pulls out each fuse one by one. When you get a drastic drop in the amount of current then you have your problem. Then you can look to what that fuse is powering.

 

maybe remove one fuse at a time and place an ammeter across the fuse contacts to see which one is drawing current.

 

ok, i did some more testing, pulled half the fuses and the drain was there. I pulled the other half, and it was still draining, but it seemed worse. So, i think maybe more than one circuit is a problem. I pulled all fuses, and the battery did not seem to drain at all.

Any ideas for finding this issue with this new info?

I would do the ammeter test while pulling fuses, but 48mA isn't suppose to cause this kind of drain right? I mean, even if I pulled fuses and got the 48 down to 20, that wouldn't be enough to cause an overnight drain like i'm seeing right?

 

what you have is called a phantom drain......basically you need to do like both me and NH USA recommended and pull one fuse at a time.....once you do this you can see which one is pulling the most current....leave it out and see if it fixes the problem then you can go from there. This might require two people, one to pull the fuses and one to hold the meter....this is the easiest way to figure out pestering problems like this.

 

Ok, I will try that tomorrow... I am not meaning to be difficult, but I am still very confused. My current measurement of 48mA is NORMAL according to many resources I have found (see below). What reading should I look for when I pull the fuses?

http://www.wikihow.com/Find-a-Parasitic-Battery-Drain
http://www.turbododge.com/forums/f4/...tic-drain.html
http://www.askmehelpdesk.com/cars-tr...ry-169730.html
http://batterychargerstore.com/what-...tic-drain.html

I will still pull the fuses individually to see if any of them really cut down on the power consumption. Thanks!

 

maybe a positive lead from your batter is chaffed a little causing it to short a little cause a drain?