Battery / current drain question

[AndyP]

I've had problems with the battery on my S2 going flat if unused for a week. I've checked the current drain today and I'm getting a 0.39A drain with the ignition off and key out. On checking all the fuses, to see where it was going, I found that if I pull the 2 motor fuses, nothing happens, but when I put them back in, the current drain drops to 0.07A, which I think is the clock.

So what does this mean?

[johne]

0.07A is 70mA which is way more than the clock which I wouldn't expect to be more than 5mA.

Depending on alarm, stereo fitted, you want to be looking at 20 to 25 mA max drain.

John

[twoqu]

Andy,
Try pulling the Motor fuses one at a time then replacing them. Might help us narrow it down to the circuit on one fuse!

[twoqu]

I was wondering about that Holding relay in the Ecu being stuck. Guess pulling the ecu might help in eliminating it!

[AndyP]

Andy,
Try pulling the Motor fuses one at a time then replacing them. Might help us narrow it down to the circuit on one fuse!

I'll give that a try.

The stereo has been removed and there is no alarm/immobiliser fitted, that I'm aware of.

[twoqu]

As far as I can tell both of those fuses are the 12V permanant from the Battery S27 & S28. The only thing I can think of that works after the ign off is the burn off signal to the Maf. Possibily also the evap solenoid. Might be worth seing if you still have voltage on pin 4 of the maf after the 20 second burnoff period. Although I would have thought the Maf would have given up by now if powered up for a week.

[AndyP]

Sorry, but the pulling of the fuses seems to have been a red herring! The 0.39A drops out on it's own after about 30secs.

I'm using a multimeter in series with the battery to show a 70mA draw, and if I use one of these

http://www.ebay.co.uk/itm/Car-Fuse-C...item3a7a69ed31

on fuse 4, it shows 60mA, but if I pull fuse 4 the 70ma on the multimeter stays

Also battery voltage is dropping rapidly, these are the readings I took

Tickover at Alternator : 13.95v
Tickover at battery : 13.75v
Battery , engine off : 12.8v but drops rapidly
Battery after 10mins : 12.5v
Battery after 3hrs : 12.39v

According to this

http://en.wikipedia.org/wiki/Automotive_battery

I've already lost 25% of the charge. Is a 70mA current draw enough to do this or is the battery knackered?

[twoqu]

What does fuse 4 feed?
Looks like a lot of the interior stuff, clock, interior lights, cig lighter, computer, radio, autocheck and make up mirror!
That last one is interesting as it only need to flap open a bit.
I would just connect the MM up from the battery to the negative lead (i.e disconnected from the battery). Leave the MM in a position to see it from outside the car. Close the car up and wait for all the things that use current to stop like the interior lights etc then once the reading has stablised start yanking fuses.

[AndyP]

http://www.s2-audi.co.uk/tech_articl...e_fuse_box.htm

Reading lights : Both switched to off
Clock : Working
Trunk light : Removed
Cig Lighter : Removed
Dome light??
Trip computer : Working
Make up mirrors : Both switch off when lid closed.
Anti theft : Not fitted
Check system : Seems to work
Air condition : Not fitted
Radio : Removed
Illuminated AG4 Selector switch??

[A80Avant]

Andy, i dont remember correctly, but a few months ago, i had similar tests done to see what could be draining my battery. I have had footwell lights fitted with Jas11N and we had in total 6 bulbs turning on when a door opens(i have 2 on the dome light) + 2 more for the trunk.

I remember my electrician saying that with everything OFF and with a mere LED lighting up (immobiliser) i shouldnt be seeing more than 0.03-4mA of consumption.

With all the bulbs on it went to 2.56mA and now that everything is replaced with LED, it goes to 0.6mA.

Please forgive me with the numbers, i cannot remember what i had set the multimeter at to do these checks, but from memory the numbers are correct and i hope the classification of A/mAmp... etc.

this is just to show that 7 LED bulbs are drawing the amount of current you are losing. So definitely something is wrong there. Is there any bulb, cigarette lighter or pump constantly on or something?

[shaun5]

I had trouble with my interior lights coming on when they shouldnt years ago, the cause was a faulty central locking pump.
There is a circuit board in it so maybe there is a fault with that? Not saying it is this at fault but worth checking.
Dont know what age your car is? My car is a 95 coupe, not sure if earlier cars are the same.

[Acidburn]

I had trouble with my interior lights coming on when they shouldnt years ago, the cause was a faulty central locking pump.
There is a circuit board in it so maybe there is a fault with that? Not saying it is this at fault but worth checking.
Dont know what age your car is? My car is a 95 coupe, not sure if earlier cars are the same.

its also worth checking that the c/l pump isn't kicking in at random intervals. My mums car was doing that and the pump is the same as whats in a coupe/s2. Every couple of mins it would try lock the door. In the end I just swapped the pump for a spare and its been fine since.

[kulster]

See if the aux water pump isn't constantly spinning

[Mikes2]

I'd use that current draw tool in every fuse location to check current draw of all circuits. Any more than 0.05-0.07A is too high.

When the bonnet is open, do you have a switch for an alarm that can still pull current. You may need to close such a switch to get the true figure.

As a guide, I had a problem with the boot light draining the battery in a Coupe. It was pulling 0.3A which was enough to flatten the battery quickly. With a new switch, the current draw dropped to 0.04A.

[AndyP]

Well I've pulled all the fuses in the main fuse ox and all the ones I could find under the steering wheel and none of them got rid of the 70mA drain
I don't understand why pulling fuse 4 does not get rid of the drain as this seems to be responsible for 60mA of it??