1.6 Petrol Draining Battery

[marci4]

Hi all,

So my A3 which I only just got has a battery drain issue. If I leave it at around 4pm and then the whole night, then in the morning the next day it feels like it's having a hard time starting. Measuring the battery voltage in the morning before starting reads 11.6V which is way too low as it should be especially as a day before it has done a 160mile trip.
I've read about the hazard lights switch light staying on and thought I was onto something, but left the car for about 15-20mins, came back and the light was off.
Unfortunately misplaced my size 10 spanner (doh!) to disconnect the battery and measure the quiescent current with meter and start pulling the fuses out so while awaiting a new one to come I thought I'd ask here for maybe some tips or someone had this problem before?

Oh, and the only errors I get on VCDS are:

01135 - Interior Monitoring Sensors
004 - No Signal/Communication
00323 - Vehicle Inclination Sensor (G384)
004 - No Signal/Communication
01134 - Alarm Horn (H12)
004 - No Signal/Communication
17947 - Clutch Pedal Switch (F36)
P1539 - 008 - Implausible Signal - Intermittent

I know the first three are alarm-related and I'll replace the siren with integrated battery once I find some working on but don't think that is causing the battery drain.

What do you think?

 

[desertstorm]

What kind of voltage is the alternator putting out when the engine is running ?? . How old is the battery ?. do you have any non standard kit such as cameras or radio / amps.

 

[marci4]

The charging voltage is 14.2V which is as it should be. I don't have any exact info on how old the battery is as the previous owner has fitted it but they claim it's around 2 years old now which could actually be true as it's pretty clean compared to everything else under the bonnet. I think the battery is in a good condition as I can sit in the car with music playing for 1-2 hours and after that the engine would start straight away.
It's a Varta 52Ah 470A and it's one of those that don't need topping up.

There is no mods or kits installed in the car. The radio is Audi Concert II which I have taken out yesterday for the whole day as I had to clean the volume knob and even with the radio removed, the battery was still being drained.

 

[RAF_S7]

There are a few "Kwik-Fit" type garages who will do a free battery test for you. I would suggest that as a reasonable step to take to eliminate the battery as the cause, before you spend a lot of time chasing other things.

 

[SootySport]

NO! not Kwik Fit, anywhere else. As it's a newish battery, it should be ok. If you have a reasonably heavy duty meter, then connect it in series with the battery lead disconnected and meter on the 1 amp scale, this will show how much current is being drawn when ignition off. Radio, alarm and ecu will always draw some current but a matter of milli amps.
Have a look in the engine bay and the fuse boxes for non OE wiring and accessories as they are often the cause of battery drain. You could also pull one fuse at a time to see if the current drawn drops dramatically but be prepared to reset some of the electrical systems when you are done.

 

[Keyz]

I'm having the same problem at the moment. I've fitted a new battery to mine and yet it still has a drain problem. I've disconnected my dash cam as it was hard wired into fuse box but last Saturday I parked up until Monday morning and it was flat. Left it at garage yesterday only to go back today and they hadn't even looked at it so I took it back and will do a test myself. Will keep an eye here in case yours is the same as mine.


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[marci4]

If you have a reasonably heavy duty meter, then connect it in series with the battery lead disconnected and meter on the 1 amp scale, this will show how much current is being drawn when ignition off.

Yeah, I will do that and this is what I meant by measuring the quiescent current in my first post I would do that in the first place but the only issue was I misplaced my spanner for taking the battery cable off and wasn't able to do that. Now that I borrowed one from a friend it's been raining all the time since I got back from work...

Have a look in the engine bay and the fuse boxes for non OE wiring and accessories as they are often the cause of battery drain. You could also pull one fuse at a time to see if the current drawn drops dramatically but be prepared to reset some of the electrical systems when you are done.

I already looked around in the engine bay and fuse boxes and there is no signs of non-standard wiring or any repairs to the cables.

Unfortunately working on Saturday so the A3 will have to wait until Sunday when I have some spare time and will hook up the meter, close all doors, lock the car up and start pulling fuses out to see which circuit is causing this battery drain.
By the way, does anyone know how much time it takes for all the computers to go to sleep so I can get some meaningful results?

Also are there any modules in A3s located in places that get moisture easily and often get water damaged?

 

[Marek196c]

instead of leaving the multi-meter attached to battery when you pull fuses put 2 terminals of your multi-meter to each end of fuse connections so you will get same effect without pain in going back and forward to side dash fuse box.

 

[marci4]

So...the culprit as it turns out is the battery.
Found some time today and hooked up the meter in series with battery and after all computers go to sleep (the hazard light switch light goes off which by the way takes around 20-30mins) the current consumption is around 50mA. That seems to be ok and there isn't any excessive current draw.
Now, I hooked up the battery to a charger that has a set of lights as an indication of charging progress. When I first turned it on, the light was red, then after about 2mins it went to orange and finally after another 5mins it turned to green which indicates that the charging is completed. This just proves the battery has completely lost its capacity and I'll need to buy a new one.

@Keyz - I'd suggest to put an ammeter in series with the battery and measure how much current is being drawn from the battery when the car is closed - should be around 250mA immediately after closing it and then after around 20-30mins it should drop to around 50mA (when the hazard light switch illumination turns off).

 

[Keyz]

Thanks mate, will get this looked at this week and hopefully get it sorted.


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[SootySport]

Just goes to show---don't believe the previous owner. Battery was probably the original, as I thought.

 

[marci4]

Battery replaced, all issues related to battery being drained went away immediately. No more check engine light after starting the engine due to massive voltage drop Thanks a lot for the help