So, after waiting two years, I finally bought a Sony bluetooth enabled stereo (I lost my job in January, so now do a lot of driving trying to set up my own business and wanted to be handsfree on the phone when I drive). I also bought the full Metra install kit (double din to single plus the wiring harness). And just to let you know, I had this exact same stereo and installed it myself in my VW Passat in the UK, and it worked perfectly (never had an ounce of trouble from it).

Well, I disengaged the OEM unit (Bose system), and installed the new Sony. Ok, so stupidly, I removed the ground clipped into the back of the Bose unit, and did not connect to the Sony unit ... Oops. But I did double check the rest of the wiring on the unit, and everything seemed fine; and the stereo worked beautifully.

Then, when I went to take my daughter to a friend's house about two hours after the install, I noticed my dash volt meter had dropped from 14 (where it has been since the day I bought this great Audi 2-years ago) to around 12, and the 'battery' warning light came on.

By the time I got back to my house (a 6-mile round trip), the meter was dipping below 10 and the car was struggling. I immediately pulled the Sony stereo out and reinstalled the Bose unit (that's when I noted the missing ground as I reattached it to the Bose head unit). My thought was this should have stemmed the bleeding, but it didn't ... and the battery was dead. I jump started the car (I'm on a hill and have a five-speed manual), and it started again. Drove about 1/2 mile and it completely died again, and I had to leave the car on the side of the road.

Next step was test the battery - 40% charge at 12v, but it wouldn't take charge, so I bought a new one. I installed the new one and the meter was still showing barely 12 volts ... and when I switched on the lights it dipped below 12. It was getting dark, so I drove the car home (1/2 mile) parked in my driveway and disconnected the battery to prevent more drain.

Is there anyone out there who has experienced anything similar? Until I pulled that Bose unit out (now I feel both stupid and angry with myself) I did not have trouble with the A4 at all ... Please tell me I haven't killed my car! Are there are any 'electric' experts out there who can offer any advice/help to get this resolved? Any practical advice (and I am not an expert nor do I have any money ... so this will be a DIY job)? I would really appreciate any help. Thanks!