Battery Draining

[noshock65]

Hi all

My A6 3.0 tdi battery keeps dumping its charge when left paked for a few hours to my flustration. The battery is new and my non audi dealer garage have teasted the battery and altinator and say all is ok. I've checked all the obvious thing suchs as interior lights left on etc. When I start up the indicator says 10% charge left but quickly goes up to full after 10 mins of driving. I have recently had a new boot lock fitted as it was not closing each time and the dashboard indicator was saying it was open and the alarm would not set either so this led me to believe it could be something to do with this but it's all repaired and the problem still exists.

Any thoughts?

Cheers

Steve

[Peter D]

Did the garage measure the quiescent current and if so whay was it. Regards Peter

[joshA6]

Also, did the garage code the battery to the car?

The A6 needs to be told what battery it is carrying. This is because there is a battery regulator between the battery and the rest fo the car.

This regulator manages consumption in the car, shuts down non essential funcitons if the battery is weak etc.

If they did not code it, this could be the reason for your troubles.

[Tay]

Hi all

My A6 3.0 tdi battery keeps dumping its charge when left paked for a few hours to my flustration. The battery is new and my non audi dealer garage have teasted the battery and altinator and say all is ok. I've checked all the obvious thing suchs as interior lights left on etc. When I start up the indicator says 10% charge left but quickly goes up to full after 10 mins of driving. I have recently had a new boot lock fitted as it was not closing each time and the dashboard indicator was saying it was open and the alarm would not set either so this led me to believe it could be something to do with this but it's all repaired and the problem still exists.

Any thoughts?

Cheers

Steve

Certainly sounds like something is still drawing power after you turn off. In my case it was the Bose amp doing it, it often died over night.

You need to get somebody to hook it up to see if there are any errors there I guess.

Checking the drain on my battery immediately (or anything up to 1hour later) showed normal drain, approx 0.07A. After this time, anything up to several hours after the car had been shut down the BOSE amp would spring to life and draw approx 0.7A.

Clearly different things can cause battery drains but getting the car on VCDS is a first step.

It seems very co-incidental that you've just had something repaired/updated, it could well be that or the convenience control unit or something wrong with the way it has been fitted to blame.

Hope that helps a bit

[BongoShaftsbury]

I've just had my MMI go faulty due to a leak in the rear washer pipe, and since then the battery has been drained too easily (flat twice in two weeks). I tried to help the the MMI dry out by pulling some fuses in the rear and noticed that some sparked when removed (i.e. an appreciable current was being drawn by something). Since I removed them the battery has been OK. This might correlate Tay's post about the Bose amp drawing current.

[noshock65]

Hi All

Thanks for the posts. There is no clear pattern to the power loss i.e the car can be parked 12 to 15 hours, as it was overnight last night, and no problem. Yesterday at 1pm 100% then at 8pm 10% paked outside the house and all I did was move it 5 yards earlier in the day. It's a strange one I have to admit. Will get an auto sparks to look at it this week.

cheers

noshock

[joshA6]

Like I said in an earlier post, are you sure that the battery has been coded to the car?

You can't possibly hope to get to root cause without knowing and eliminating this from your toubleshooting.

BTW - I understand that the battery meter in the car is not even close to being useful. I am sure an Audi Tech will post and say as much.

[JimC64]

Man, this sounds ohhh soo similar to me!

My A6 now nearly 4 yrs old has had sooo many cold start / non start issues with the RAC called out several times, 2 or 3 new batteries ( I've honestly lost count ) with numerous checks done by the dealer..........

I had a fail to start around 3 days ago when the weather was bad and an almost "fail to start" the day after......jump leads required etc etc.

I don't even hesitate any more, call the dealer, cars failed to start AGAIN....I'm going to get it started bring it in, please have a courtesey car ready and you can have mine for 3-4 days to play around with and see if you can find the issue AGAIN!!!!

Currently driving an A5 1.8T that drinks petrol like its going out of fashion!!


Has to be a battery drain somewhere.....but where???

[a8 tech]

everything must be checked via battery manager

battery manager history records the time and date plus possible circuit active

alternator must be checked at the manager not the alternator

the battery manger must store the new battery type via coding which is only possible by inputting the number on the new battery sticker.

The battery meter reading incorrectly requires a software update

if no obvious drain can be read from battery history then you need to test closed circuit drain

open all the doors, bonnet and boot

click over all the locks so they are in the locked position

turn the ultra sonics off

lock the vehicle

leave for at least 2 hours and connect an ammeter to the negative battery earth cable

the readings may fluctuate due to the close proximity of the battery manager on the earth lead

you are looking for a reading below 70 milliamps after 2 hours

Common drains

phone control unit

dsp amplifier

radio control unit

door control units

water ingress across boot lock

[manclad]

you are looking for a reading below 0.070 milli amps after 2 hours

Clarification please.

Should that be 70 milliamps?