Author Topic: Audi A3 battery problem  (Read 8851 times)

Offline HJBpercy

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Audi A3 battery problem
« on: February 14, 2008, 11:32:15 AM »
Can anyone help with this difficult problem? I have an Audi A3, about 6 years old. No previous problems with it.

Just before Xmas, I went to start the car in the garage and the battery was totally dead. My immediate diagnosis: battery 6 years old, buy a new battery. So, I trickle-charged the battery and then started the car, no problem, and drove off to buy a brand new Vater battery. Problem solved, or so I thought.

A few days later, I again went to garage to start car and battery was again totally flat. Ah, I thought, wrong diagnosis, it must be a charging fault, probably a faulty alternator. So, I took the car to the local Audi dealer. They have a £54 diagnosis service. They had car for 24 hours and could find no fault, but suggested that perhaps the new replacement battery was not fully charged when purchased,
and general running about had taken more charge out than had been put in, so battery again flat. I swallowed that and drove car home. Car stood in garage for about 4 days unused, went to start car and, once again, battery totally flat.

So I started car with jump leads from re-charged "old" battery. Took car back to Audi dealer, they had it for a further 5 days, supposedly on continuous test, and, once again, could find no fault.

Yesterday morning, went down to garage to start car, it had been stood unused for about a week, and the battery was again totally flat and reading 7.5volts. Again, I have re-started car
with spare "old" battery... no problem.

However, I am now myself monitoring the battery and current drawn, with everything switched off,  but car not locked. After 24 hours since switching engine off, there is 13,05 volts across the battery
(this is measured to the nearest 10mV and is very slowly dropping at a few mV per day, as I would expect).  There is also a small current drain of either 30 or 50 mA ... is this the clock? The drain seems to switch from 30 to 50mA  occasionally. However, a current drain of say 50mA is about 1Ahr per day, so it would take about 2 months to
flatten battery this way.

Some one told me that there are some NiCd batteries in the car for the anti-theft alarm, which could be faulty or some sort of controller in the dashboard. It could be a faulty light-switch in glove-compartment or boot or somewhere, I am about to check that.

Has anyone any suggestions the haynes manual is no help????