Wipers - Strange noise......

Hello,
I have been trying to resolve some issues with my S3 around the alternator and found some strange things...

The strangest seems to be the intermitten wipers. With the engine off, the wipers work well, with no noise. However with the engine running I can hear a clicking sound from within the cabin. I have identified the noise as the relay box under the dashboard. I have taken the relay cover off and there does not seem to be anything wrong. This is confirmed because of the silent running when the engine is off.

I noticed that if I switch the wipers on and then rev the engine, the clicking sound speeds up. It seems to be therefore linked to the speed of the engine, but I do not know why. Does anybody else know, or have come across this before?

I have also found out this afternoon that the volt meter in my car is out but as much as 1 volt. Doesn't seem much but it does mean that the red battery light comes on alot when i use the elec windows, or the wipers. Does anybody know if there is an adjustment method?

Thanks

Firstly the volt meter on cars of this age is not very accurate and is only an indicator of circuit voltage not of load ( for which you need an ammeter), so I would not be overly concerned with the reading being out by one volt. I suspect your problem with the red light is due to a battery or a charging issue. You need to check the output of your alternator and to see if it is charging the battery. You can do this by putting a multi-meter across the battery terminals with the engine running at around 2000 rpm. You should get a reading of between 13.5 to 14 plus volts. If it is below this check the output at the alternator to confirm the figure. If it is low the problem is the alternator. If the reading is ok at both ends you need to have the battery checked under load to make sure it is in good condition and holding a charge.
Without seeing your car anything else is guessing, but the fact that the clicking speeds up and your red light comes on when you use the electric windows is pointing to the battery being down on power possibly due to it being on the way out. Don't going buying a new battery though until you have checked out the charging circuit.
If you have not got a multi-meter or not sure about using one a Battery Charging Tester is a good cheap investment VWP - multimeters & circuit testers. As far as the clicking is concerned I would suspect it is just the relay doing its switching for intermittent wipe which picks up as you increase the power ( again possibly due to a poor state of charge). Hope this helps.

Thank you for the response. I have bought a new battery as I am not sure how old the last one was and after it had let me down so often it was time to replace.

I have used a multlimeter and get 12.6v with engine not running, and 13.8v at 2000revs. As I switch things on I do notice a drop in voltage as you would expect but never below 12.2v. So not too worried about the reb battery light.

My concern is the wiper relay clicking rapidly when used and how this increases as I rev the engine. Can i prevent this?

As I said before its difficult to diagnose a problem without seeing whats going on. The clicking in the relay could be down to the relay getting old and the contacts shorting so you may try changing it out as it is not an expensive part. Your meter readings suggest a fully charged battery and the 2k rpm reading is fine. So it may well be a tired relay. You can open up these relays and give them a spray with proper electrical contact cleaner (not WD40) which can prolong their life... but I would change it over. If the relay is clicking rapidly on intermittent wipe I would think it is the relay breaking down. Back on the red light... this could be down to the voltage regulator or the alternator as it should not come on even with everything on. Does it come on as you put load on at 2000 rpm? If it does it is pointing to one of the two.