Audi A3 8P 2006 battery drain

[juanchoA3]

Hello guys. I recently bought an audi a3 2.0 fsi sportback 2006 and the first thing i noticed was the battery going flat in less than 24hs so bought a new one. After 3 days the new battery went flat again so i started testing. I noticed the red triangle shaped hazard light is always illuminated (stuck solid with the dimmed leds). The consumption im getting with the multimeter is around 1.2 1.3amp with the car locked. When i remove the fuse F12 that manage the "data bus diagnostic interface" the consumption drops around 0.32amp to 0.4amp and when i remove the F10 that manage "Motronic control unit
Motronic current supply relay
Terminal 30 voltage supply relay" it drops near to 0.08amp.

With the 2 fuses off the red triangle shuts down.

I know there are a lot of threads on internrt but honestly i couldnt find a certain solution. Please help is cracking my head thank you!!! 

Edited September 10, 2023 by juanchoA3

[cliffcoggin]

Juan.

You really need to get the electronics tested. There is clearly a short circuit or some other fault that is draining the battery, but the information obtained simply by removing fuses is not going to provide a definitive answer.

[juanchoA3]

Hello Cliff, thank you for reply. From where should i start testing electronics? yesterday i removed the comfort module which is a black box rear right in the trunk ( 

) and seems the carpet a little wet but not the module. Even when i removed the switches i still got drain battery

[cliffcoggin]

Juan.

If you don't have an OBD code reader you will need to take the car to somebody who has, or an Audi dealer, or an auto electrician. That reader will give a list of error codes which will need careful interpretation because many will be a consequence of the primary fault.

[juanchoA3]

1 hour ago, cliffcoggin said:

Juan.

If you don't have an OBD code reader you will need to take the car to somebody who has, or an Audi dealer, or an auto electrician. That reader will give a list of error codes which will need careful interpretation because many will be a consequence of the primary fault.

Hi Cliff. I am working in the car right now. After pulling and putting back all the fuses i got a consumption of 0.7amp when i unplug the f9 fuse which manages "Navigation system with cd drive control unit, navigation system tuner for TV, satellite radio, telephone transmitter and receiver unit, aerial amplifier for mobile telephone".

The consumption drops to 0.12amp and the hazard light goes off which means every module is sleeping like its normal. Tomorrow i will buy the vagcom cable and try it 

[Magnet]

Hello Juan,

So are you thinking .12 amp (120mA) is OK? I would have thought the ‘fully shut down’ current draw should be more like 50 to 60mA.

Kind regards,

Gareth. 

[juanchoA3]

7 minutes ago, Magnet said:

Hello Juan,

So are you thinking .12 amp (120mA) is OK? I would have thought the ‘fully shut down’ current draw should be more like 50 to 60mA.

Kind regards,

Gareth. 

It was 1.15amp before. I've disconnected the dashboard and the current consumption is 0.11 0.12amp with the F9 fuse installed

[Magnet]

Ok, I understand 120mA is far better than 1.15A., but still too high if everything has ‘gone to sleep’. 

[juanchoA3]

29 minutes ago, Magnet said:

Ok, I understand 120mA is far better than 1.15A., but still to high if everything has ‘gone to sleep’. 

Ok, i will try tomorrow with the car locked and the multimeter bypassing, maybe after 30m or 1 hour the consumption drops even more. Thank you!!

 

edit: when i was trying fuses (left side interior) one by one the number 16 droped some Ma which manages:

Edited September 10, 2023 by juanchoA3

[JohnHa]

I hope this may be of some help to others seraching on battery drain.

My 2005 A3 battery went flat so, after recharging it, I decided to measure the current when (I thought) everything was OFF.  I got a reading of about 1 Amp.  Strangely the reading was about 3 Amps when the battery was flat.

First, I had forgotten to ensure all the doors were closed to ensure the courtesy light was OFF.

Second, it took about 30 seconds for the initially high reading to fall to a few tens of milliamps. 

I reasoned it must be something to do with the alarm ...

[Magnet]

Hello John,

Taking 30 seconds to fully shut down and give ‘tens of milliamps’ discharge seems fine to me. Anything around 50mA  after the car has fully shut down should be OK. 
Kind regards,

Gareth. 

[cliffcoggin]

12 hours ago, JohnHa said:

I reasoned it must be something to do with the alarm ...

Indeed it is.