Hey all.

Yesterday morning my car wouldnt start after sitting unmoved for a couple of days and i had to get the recovery guys out.

Ive a 6 year old B7 S4 and the battery failed there test and only had 10 volts. There was a small drain of (from memory) 0.7 volts (or amps i forget which) and the guy said that he would normally expect to see 0.1 and over time thats whats killing a weak battery.

Would your advice be to try and find where the drain is coming from? If so how would a newby like me go about that please - or - just get a new battery.

After an hour run home at 80/90 mph the battery seems charged up again.

I hope that makes sense.

Thanks for you time.

Warren

 

Diconnect the battery, either the ground or positive cable at the battery end. Do not disconnect both cables. Turn off all electrical stuff in car. Connect an ammeter between the battery post and the end of the cable, set ammeter on highest AMP range and then adjust meter as needed to get a reading. If it is over 0.2 AMP there something drawing current when it shouldn't. With the meter connected, remove one fuse at the time and replace till you find the one that is causing the current draw. Now you will know which circuit to look at, but you will need the electrical drawings to follow it.
Before doing all of this you may want to see if lights ore going off, including the one in the glove box.

 

Awesome. Cheers Pete, ill try just that.

W

 

Wobblewoo - did you discover what was draining your battery?

 

Hello.

i did not. It went into Audi and they tested the battery and said that it was fine. The alternator was putting out over 100 Amps (from memory) which they said was huge.

I did get a list of fuses and was going to go through removing and working out where the drain was coming from but had trouble finding a clamp meter that will measure down to 0.1 amps.

Not had a problem since so may have just left a light on when the battery went flat.

You having a problem then?

W