Won't start - 2nd time this week

[Oli18]

Great results there. Don't suppose you have any pics of what it looked like before or after cleaning? ... always useful for a sticky and the rest of us if we ever face it.

Oli

[The_Laird]

No pics I'm afraid - still not got used to having a camera on my phone!

But it was VERY crusty with that blue coloured muck that electrical terminals seem to foster. Had to get a file to the flat on the chassis and to the washer, as just sand paper wasn't going to shift it.

Next time you have the front o/s wheel off, it's probably worth having a look. It's just where 'the librarian' says, you can unclip whatever the purlple wire goes into then, for easy access, I removed the battery/starter motor cable junction box with just a couple of Allen keys and voila - there's the earth.

[The_Laird]

Forgot to say - in the picture from 'the librarian', the wheel arch liners are removed. You don't have to do this as there's a small 'panel' about 6-8" square (but it's not square - it's shaped) that you can easily remove - just one plastic nut and a circular clip to get access. You can identify the panel easily as it has some Audi numbering on it moulded into the plastic.

[The_Laird]

Didn't start this afternoon again FFS! Battery down well below 12 volts before I tried, so suspect that it's useless now. Off to halfrauds for a new battery tomorrow.

[B@fink]

you said it was at 12.25v......thats low anyway................from what i read on wikipedia batteries are 12.6ish at rest (check out automotive batteries on wikipedia) at 12.25 you got 50%ish power in it. Not good for a V8 in winter

You probably had a dying battery and the crud was making it harder for it to do its job too.........

[graynada]

Tis the time of year for roiuting out the weak batteries. For future reference, when a low battery starts causing starting issues I have found the following checks useful;

Note values are from memory so could be +/- 0.5 volt.

1. As mentioned before check the voltage at the battery with the engine running, should be about 14 volts. Anything test 2 result to 13.5 volts suspect wiring/earths (see tests 3 and 4).

2. With the engine off check the battery voltage under load. This means switch on head lights, main beam, heated screens, heated seats. The voltage will drop but should hold around 11-12 voltsish. If the voltage continues drop and goes south of 9.5 volts, chances are your battery is dead. Take it to a motor factors and they should be able to test it properly for you with a proper load probe. Before doing this check be prepared to not be able to start the car after, so be somewhere you can jump start.

3. Measure the voltage between the -ve battery terminal and chassis and -ve battery terminal and engine block. Should be less than 0.1 volts. Anything more start looking at battery terminal connections and earth points as described above.

4. Measure voltage between +ve battery terminal and alternator +ve, and +ve battery terminal and +ve in main fusebox. Should be less than 0.1 volts again, wiring and connections likely causes of any high readings.

As I say all from memory so happy to take a hit on the exact values. When I get chance I'll do the readings and update, unless anyone with a good battery beats me to it.

Another import thing to remember with starting issues is just because you have a new or recent battery do not rule out it could still be duff. Have seen this many times.

[The_Laird]

Much appreciated guys. Off for a test and, probably a new battery, at lunchtime