Battery Drain Question

[apole]

Hi.

Had my A6 since mid Dec. It had been mostly off the road prior to this since September.

One thing I noticed was the battery display in the MMI kept going low, I put it down to having stood combined with me spending time learning and setting all the things up without the engine running. When it was serviced I asked for this to be checked, a new battery was diagnosed which seemed plausible as it was 5 years old and had stood.

Well initially all was well, however this week I noticed the advanced key etc were not working, checking the display there was only one block showing. Car starts fine, and I put it on charge all day which has brought it all back.

However this isn't right and there is something that will be draining the battery. I know on other cars I've had that leaving things like the headlights and wipers in auto can drain the battery so I've turned those off as a test.

I will have to get out and spend some time checking first what the drain is, and then what circuit is responsible. The car also has a tracker system fitted so that would be a factor.

Are there any known culprits such as the MMI or radio that anyone is aware of?

Thanks in advance.

Andy

[Issac Hunt]

Could one of many things. You need to measure the drain on the battery for starters.

[singhl]

It will be the radio / sat-nav unit, not shutting down properly, it keeps the rest of the car awake, and drains the battery. The battery manager will then turn items off to save battery (e.g the advance key.....) a scan will reveal a number of stages in the battery manager, turning things off. Batteries do not drain themselves. I had the same issue my car is a 2005 3.0tdi quattro. I had the battery manager software updated, as there is a bug in it , to confirm it is the radio, try switching it off before switching car off, do this with a long press off the power button by gearstick.

I ended up putting the fuse for all the audio and sat nav in the boot on a switched relay - so when car is off, all that crap is off, switch car on and it comes on.

My car still has its original 110Ah battery from new - starts every time.

[apole]

Thanks, that is very useful information. I need to do that update to 5570 on the MMI and modules, not sure yet if that battery manager is part of that. That is what I ended up doing on another car I had issues with, so if the update doesn't fix it and it proves to be the radio I have a plan.

Thanks again.

[singhl]

Battery manager is not part of the MMI update - it can only be done at Audi dealer, the software in battery manager is updated, but the main culprit is the audio/sat-nav staying on after car is turned off, been 2 years since i fixed my one, and it has a 7year old battery in it, so all this "oh my battery is dead - you need a new one", just masks the root cause, which is dodgy software in audio /sat nav.

[eestimaa]

I have same problem with my car, it won't go to sleep mode. If I remove passenger side number 10 fuse (5A), then everything is ok. MMI have latest version 5570, so I need to update battery manager also?

[apole]

Hi,

I suspect the issue is not just with the battery manager software, but just how the MMI and radio switch off. Looks like they take too long before turning off after you have left the car and subsequently drain the battery. If you use your car most days you are unlikely to notice, especially since the battery monitor display in the MMI is lost with the newer MMI software.

If this is the case, and I will need to test this on my car beforehand, the best approach is to use a relay to cut the power to the MMI etc (namely the supply via the fuse you mention) when the engine is turned off.

Thanks again for the information, very useful and saves alot of time searching around.

[singhl]

The fuse for sat/nav/audio/radio etc is in boot just above where the battery is (above the jack and tools) on my 2005 3.0tdi Quattro. Can't remember the number but just ask and I will look in the car and let you know.

[apole]

Quick update.
I have turned the wipers and headlamps to off rather than auto, and ensured the MMI is off before switching the car off. Been standing whilst working away for many days, come back, before starting checked and battery showing as full. Thanks for the tip, makes a big difference.

[singhl]

One thing i forgot is to turn off the traffic management (TPMS) off, so they do not startup the radio, somewhere there is a setting to start recording updates at a certain time, turn if off, or the radio will wake up.