A6 Avant 4WD battery dicharges overnight

[tally1]

I have a January 2006 2.7Tdi 4 WD Avant(with MMI)that when locked discharges its battery overnight.It happened a couple of times 3 months ago but is now happening all the time.Nothing is obviously left on eg lights etc.The battery has been changed even though it tested ok.....the rear deck door microswitch has been replaced as it was showing a fault in the log.Over the last few weeks we've been getting intermittent false tyre pressure warnings(it's got the Audi sensing device) and the fuel gauge not working-although they do appear to now have gone away....but the battery discharges to the 10% level overnight and,of course,the car then y needs jumpstarting.The car is absolutely Audi standard with no after market gismos......anyone got any thoughts?

[daycartes]

Hi tally1,
I recently had this problem but a battery change cured it. Is your new battery the correct model as mine had to be bought specially and it cost £120 !!!

Just a thought. I removed both cigarette lighters as I had a feeling that if the element had shorted this could drain the battery as it is a constant on. I've not retried them as I didn't want to tempt fate.

The only other thing that I can think of is the recall 19F8 done to correct a continous radiator fan problem see elsewhere in this forum.

Please let us know the cause when you find out.

daycartes

[singhl]

If your car has sat nav and mmi, then there is a fault with early software where when the car is switched off, the radio stays on (even though screen is blank) and this keeps othe systems in the car awake, and batter drains.

The long and short of this is the MMI software needs updatin to latest (this updates the radio to cure fault), also the battery manager in the car can be updated by audi to later firmware (stoke audi did this formme on my C6 3.0tid quattro), and fixed my battery problem, never dies since, and the battery is from 2005.

See http://www.fileden.com/files/2007/3/...b.91-07-13.pdf

[tally1]

Thanks...what year/reg is yours? Tally1

[singhl]

2005 3.0tdi quattro