alternator

[hoover]

Hi to all, my voltage gauge is reading 12volts, it usually reads higher, I suspect the alternator is not charging the battery but first wondered if a faulty battery could upset the charging rate or something else, any thoughts please.

[mytrplseven]

12 volts (blue wire) to the alternator will excite the alternator. If it isn't available, after about 2000 rpm, the alternator will self-excite. Are you getting a warning light that tells you that you're battery is at or below 12v? In any case, with a voltmeter on the battery and the engine running (which is what I assume you're doing) you should read about 13.8 volts when the alternator is running properly. Make sure the alternator is spinning and the belt's tight. Then check any appropriate fuses and verify the ground wire to the top of the bellhousing is clean and secure. Next item is the voltage regulator that plugs into the back of the alternator. Go on ebay to see what they look like. They aren't expensive and although you need to either remove the alternator or pull the intake system out of the way so you can get to the alternator from the top to replace the VR. You could just pull the alternator out and take it to one of the auto parts stores that will check it for you, but if you do, it's a good time to change the VR while it's out.

[hoover]

Thanks for all that info, very helpful. I have no warning light, just noticed the car voltage indicator reading 12v normally 13v approx. Will make the checks you suggest.

[968 GUY]

The voltage regulator is on the back of the alternator and can be removed with a short phillips screwdriver (2). Regulator on one of my 968's just went. Stopped by the local auto electric repair guru and he sold me one for $25. Now the meter is showing 14+ volts.

[hoover]

Just to update the guys who replied, I bought a decent voltmeter to check the output more accurately, the battery with engine off reads 12.5volts, when the engine is ticking over the voltage across the battery goes to 13.5. more than I thought but perhaps still a little low.

[mytrplseven]

I had my gauge cluster apart to replace the odo gear and fix the crappy lights. At some point I must have moved the voltaqe needle a bit because when I put it all back together, I was indicating only 12 v when the alternator was putting out 13.8 volts. When the engine was off, the gauge showed the needle well below the orange bottom of the scale. So I looked at a couple of gauges on ebay and the picture in the owners manual and all I needed to do was move the needle with my finger until it was on the orange square according to my findings and viola! The needle now shows almost 14 volts. Perhaps that's your issue in a nut shell. It's easy to push the needle to where it should indicate.

[hoover]

Yes that's a thought, although I've not fiddled with anything in that area, as I'm getting some charge I'm inclined to run it for while and see if things vary. Thanks for the input.