707chris

Just purchased my first audi, and on the way home discovered some things. Battery did not budge from 9% on the MMI, and it was a total of ~4 hours drive. So I can only assume the alternator is working due to the car making the lengthy drive, but possibly some other module that is failing and not allowing the battery to be utilized.

I have searched and have come up with my best educated guesses from my research of several different threads. But both of these problems were in the previous D2 A8. Not many threads referenced D3 A8 battery issues.
-Junction box in right front wheel well
-Alternator Regulator
-Battery Regulator

Unfortunately I have not been able to hook it up to VCDS/Vag Com due to it sitting with a blown shock and it being unable to recharge battery. So I'm just really looking for anyone with a familiar sounding problem that found a fix. Thanks so much and can't wait to make contributions to the forum!

jakematic

Welcome and congratulations on the A8 - it will ruin you for every other vehicle

What is the date code on the battery ?
It's in the right rear compartment in the trunk/boot.

If it's over 3 years old you more than likely need a new one, especially since it didn't make it above 9%.

MP4.2+6.0

+1 That's the low hanging fruit obvious first one, rather than other stuff

707chris

Haha I know what you are saying, previous owner of bmw, mercedes, honda, nissan and so decided to give Audi a shot. Plus the price I got it for, it was a no brainer.

Already have ordered:
-Front Right Air Shock (Left in the future.. Thanks Holidays)
-Timing Belt Kit with water pump/thermostat/serpentine belt
-Aluminum Pipe for Oil Cooler (car had service records noting it was leaking from there)
-MMI Gear Replacement Kit

I know there is torn upper links, and I assume control arm bushings are next but I'm going to wait until I get the bulk of the current parts list taken care of.

As too the date of the Battery I cannot find a sticker on the top, but it does say 'Volkswagen Original Batterie.' Though supposedly it had been replaced in 2013.

jakematic

Bravo !
You're off to the races and have obviously done your research... we likely

You said you have genuine VCDS, but do you have a service manual ?

I'm wondering if the relay for the air compressor didn't fuse and eventually kill the battery by running incessantly...

May want to put your year/model in your signature and update your location too - makes it easier for us to figure out what we're dealing with. THanks-Jake

707chris

I actually don't have VCDS or a manual. I'm going to order the software from Ross-Tech soon, and postpone a manual unless I really need it. The hardest job I see in the future is the timing belt/oil cooler and it seems there is plenty of information on it. And I'm not sure if the compressor is dead or not, the car had air in the other 3 wheels other than front right. And I tried to switch the suspension settings around to see if I could get the front right to inflate but no effect. The driveway to the previous owners house was like a slightly rounded curb. A good 3-4" increase in height to the driveway from the road.

Kkirkg

Did you get a battery warning indicator? I had the warning shortly after delivery and it required a new battery. And the salesman said "Oh yeah, I noticed that too." What an idiot and needless to say he is no longer there . . . back to flogging GM stuff I think.

Mister Bally

If the car starts and runs, you may have a battery manager module that just needs re oding to get the MMI display to show "better" percentages. Mine needed it for awhile and I was able to drive it for months without any incidents at all yet the MMI indicator said 10-20% tops.
If it hesitates to start or cranks slow, best to replace the battery assuming no charging system indicator on the dash display or idiot light illuminated.

Basically, I hardly ever look at the battery condition on the MMI.

MP4.2+6.0

If you can't get battery charged, disconnect it and charge it with a charger stand alone. If you don't have a charger, another pretty early purchase...more so w/ a D3 perhaps.

And yes, as Mister Bally says, try recoding battery. Either grab the number from your current one if it is an Audi/dealer battery (and not already entered correctly), or just augment the final digit of the currently stored serial number by 1.

707chris

Been doing more research and it seems I'm just going to run Vag-Com after the car is in sleep mode to discover which module(s) are still active and draining the battery. I'm leaning towards the MMI console area as the previous owner said liquid was spilt on/in and a couple buttons are slightly sticky. Good can of electronic cleaner is my first attempt before replacement.
And to address Mister Bally, the car won't hold a charge overnight or even a few hours. The car won't recharge the battery enough to restart it. But it will drive for multiple hours (i.e. 4-5hours of continuous driving) so thats why my opinion is the Alternator is still good.
I have purchased a new battery and will install it once I get my hands on the software. I don't see an advantage to putting a battery in and letting the car sit drain/damage it before I can diagnose whats causing the drain & install the parts being shipped as we speak.
Surprising for a Lawyers car that it was pretty neglected. 134k and no timing belt done, Blown shock, MMI Gears, Coolant leak @ Cooler. But again, for the price I couldn't resist, and all the parts so far is still under $1000… barely.