Hi all,
This is my first time here, I have Audi A4 2009 Premium Plus
I have a battery problem for at least 6 months now.
I'll try to keep my story short
One day my battery was completely drained, AAA jumped me and suggested I should look into getting new battery. The battery was over 2 yrs old so I went to Interstate and got a new one. A week later the same thing happened, I went to my local shop to check the alternator which was fine. Recharged the battery and 1-2 weeks later battery dies again, my local mechanic said that I needed original Audi battery. Well I returned Interstate one and got Audi, they coded the battery to the car. 1 month later same thing, car completely dead although the batter lasted twice as long vs Interstate battery...
I drive the car on the daily basis and the battery gets drained overnight.
Went back to my mechanic and they said it's the radio, they took it out - sent it somewhere to fix putted back in and 2 weeks later dead again! They ordered new radio - 2 weeks later with the new radio and the car is completely dead ( they coded the radio to the car as well )
I was so frustrated, but my mechanic insisted he will still figure it out
We agreed he will keep it 1 week longer, I'm afraid I will have to take the car somewhere else and start all over again
I have no clue what's going on, the car was perfectly fine all the time ( only 60K miles on it ) and all the sudden this battery issue !
I will probably go to the Audi dealer or maybe another Audi certified mechanic ( there is one more in my area )

Please any advice, I'm desperate at this moment

Thank you all for any help

 

You can check for a current draw by shutting off the car and all other devices, disconnecting the positive cable from the battery, then using a volt/amp meter, place one lead on the cable clamp, the other lead on the postive battery post. With all the bullshit they have in these things, you will see a draw, but it should not exceed.5 (1/2) amp. If you see something like 1 amp or higher start pulling fuses until you find the culprit. If that doesn't work, you have a short. Of course, the dealer should be able to track this down real quick using the equipment he has on hand.

 

Thanks Dan, yes if my mechanic doesn't fix the problem I will go straight to Audi dealer

 

You could also see if anybody has a heat-sensitive Infrared camera often used to check insulation on houses in the cold, hot fuses in industrial equipment etc (we have one at work) - taking images of the car when it has been sitting for a while could show potential hot-spots. A friend had a similar problem to yours (not Audi); with the camera he found that the lamp was on in the glove box due to a broken switch.

 

Your B8 has a battery manager. Traditional methods of finding draws will not work. First step is to get an Audi genuine battery and have it installed by a dealer. The Battery Manager will have to be reflashed to input the new battery info. Then, the tech can look for events in the battery manager history and begin to narrow down draws using the tester. Unfortunately, B8 platform is really dealer-only when it comes to electronics.

 

I have the same issue with my car and my alternator and battery were both replaced in May 2017. The voltage went down from V12.75 to V12.40 overnight. I am going to check for voltage draw this weekend and I will update the progress.

Note: The alternator is providing V13.8 to low V14 when the car running. My car does not have Audi battery instead the previous owner installed Duralast.

Also read Codes: 00446: Function Limitation Due to Insufficient Voltage and 0053: Supply voltage. Not sure if because of having none Audi battery and the shop installed them cannot code the new battery to the car.

 

Just providing an update to this issue, the aftermarket alternator wire is drawing current at 0.4 amps when car is not running.