Measure at the battery terminals with the engine running, if the alternator is ok you should get 14V or thereabouts(for most cars at any rate), if its only reading 12V may well be time to whip the alternator out and get it checked/fixed.
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You do not have a battery or alternator problem, this is normal behaviour for our cars if you use the Audi fitted battery meter as the reference for your battery voltage.
To see if you really do have a problem you need to use a digital voltmeter actually on the battery terminals themselves and on the output stud on the alternator to measure the true voltage.
Where the Audi fitted battery meter measures voltage is affected by voltage drops in the wiring loom caused by loads in the loom such as switching on the lights but it doesn't mean that there isn't the correct voltage at the battery or alternator which is why you need to use a quality voltmeter directly at the battery and alternator.
JohnLeave a comment:
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I'm not sure its a regulator problem, I'm no expert but these things work like a motor in reverse so they have brushes etc in there. Good chance after 18 years they could be worn out.Leave a comment:
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Does the regulator 'regulate' the low end voltage as well? I read somewhere the it stopped the voltage getting too highLeave a comment:
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completely, I had a regulator failure but the cause was that the whole this was full of gunk. It actually seized solid after a while. You'll get good peace of mind with a rebuild which usually includes new bearing etc etc. You'll get a new alternator belt for £5, an easy change while you're there.
Tip: loosen the connectors for the wires while it's still solid on the car. this will save you trying to wrestle with it whilst the weight of it is pulling against the wires.
ShaneLeave a comment:
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Most common problem is the voltage regulator. You can get the alternator reconditioned for around £100, new bearings, regulator, and clean up the internals. Or just buy a regulator and fit it yourself, simple job as its held in with two screws. Unless the car has done big mileage you can get away with just replacing the regulator.
Test the car with another battery before you spend any money, and make sure you disconnect the battery before working on the alternator.Leave a comment:
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Yeah nice and easy, spray the adjuster and the mounting/pivot bolts with penetrating fluid before hand as they can be seized up. Its just bolt on bolt off, big wire and a little one on the back IIRC.
Grease up the adjuster when you have the alternator off, means less hassle next time you need it to move.Leave a comment:
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Cheers. New member here, hence all the posts! IS the alternator easy enough to change?Leave a comment:
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Put a wanted post up on here, should be able to get one without spending a small fortune. Could also get one from a 20v 90/coupe in a yard, can be hit and miss though.Leave a comment:
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Cheers mate. Have been having a look about and new ones seem a bit pricey, any ideas where a couple source a cheap one?Leave a comment:
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surely the alternator, if you can find an "auto-electric" workshop they can easily test itLeave a comment:
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Alternator problem?
Have just recently bough a 1992 3b S2. Couple of wee niggles with it which I'm trying to sort out. When I got the car, the battery was fine - showing nearly 14 volts. Now, when i start the car, the battery meter shows just below 12V, and will go down if i use any lights, wipers etc. If i swith the lights off then it goes back to just below 12v again. Am I wrong in thinking that this might be a problem with the alternator? Have checked the battery and it seems to be ok.
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