Hi first time post.


I have a 2007 A3 3.2 with 70k miles on the clock. I've owned it from 55k. When I first bought the car within 1 week the battery was dead. The quick fix was to replace the battery, I soon found out that it was not the battery but indeed the alternator. Ok, got the alternator installed (fall 2014) car ran fine all winter long, and I live in Minnesota where it gets -20. Had no issues. So spring 2015 rolls around, and all of the sudden I'm having starting issues again, the battery is dead. This car is a daily driver I commute 20 minutes to work one way. Plenty of time to get a charge from the alternator, imo.


So, I've been doing a lot of research on this forum in past threads, but coming up with no real good answer. So I decided to start trouble shooting the electrical system on the car. Here is where I'm at so far:


13.3-13.5 Volts off the alternator with the car at Idle and no radio or nav or head lights on.


12.8-13 volts off the alternator with all the electronics on and high beam headlights


Voltage is the same at the trunk mounted battery terminals.


I'm thinking that this is still above the 12.6v of the battery, so it should be charging. Also take a look at the pictures, I'm a little troubled by the paperclip fuse that some jackhole installed. What is that wire for and what size of fuse is it supposed to have. Also, in picture number two, connected to the remote battery terminal in the engine bay is a capacitor looking device. What is that thing for? Sorry, I'm not a total car noob, just not used to working on German vehicles.


Thanks for any help!

 

The battery sometimes drains at idle. When it falls to about 12.0, the idle RPM will increase until the battery hits 14.4.

That paperclip has to go. It's probably causing the computer to see 14.4 volts immediately after boosting idle. Maybe there's another one in the trunk.