Hi,

My A4 (1996 2.8 nonQuattro) has had two peculiar incidents where the battery has run dead without any usual cause. Both came after I had not driven my car for several days, which is a normal driving habit for me. The first time 2 months ago I was walking out to my car and noticed I could hear the radio inside. At some point it had switched on by itself during the 5 days that I hadn't driven it. The radio button was in the "on" position that typically turns off when you remove the keys and it had been off when I previously left the car. As soon as I tried to start the car it did not have enough power to run the radio or interior lights anymore, and the trunk latch could be heard clicking. I chalked it up to extreme cold weather at the time.

The second time was this morning. Again I hadn't driven it in about 3 days. I went to start it and the battery was almost completely down. No driving or interior lights had been left on, the radio button was in the "off" position as I have been leaving it since the first incident. There is no obvious reason as to the drain of the battery. When I turned the key a few funny things happened like the seatback moving down on its own and the trunk lock clicking repeatedly which I assume probably happened from the low battery condition. Weather was normal this time around: 40-60F.

Does anyone have any ideas what the cause of this might be? An electrical short somewhere turning things on or draining it? In between these two incidents everything has been running relatively well and the battery voltage has seemed to be normal. Also, for about a year my cruise control has ceased functioning and the climate-control display comes and goes if anyone thinks that may be related or has any information about correcting them.

Thanks,
Brian

 

Its possible the cruise and ac are related but unlikely. Hook up a meter and check for you current draw with the car locked. It should be around .050 amps. If its higher than that start pulling fuses untill the draw goes away. Then you have the circuit the draw is on. All you have to do is find the componant that is causing the draw on that circuit. You can unplug things to isolate it.

 

Dude i told you last time check your alternator out. An easy way to check it by yourself is to jump the car up when u got it running, then remove the positive terminal (red). If the car stalls out then its def your alternator. If the interior $hit goes out then its not your alternator. I'm almost certain that its your alternator because random stuff is going to stop working.

 

hmmm.... never heard that type of test...

but if you think its the alternator that would test it.

 

hello,
My car did weird stuff and replaced the alternator and all is fine with the car running now.. try the alternator...

 

Running the car with the battery disconnected is a bad idea. The battery is a shock absorber for the electrical system. It absorbs spikes and running your car without it could damage one of the many modules on the vehicle. When most alternators fail they have no voltage output whatsoever. So the volt gauge on your dash would read close to 12 instead of about 14. A cheap volt-ohm meter for any store would show the same readings without the risk of damge to the electrical system.