Posted by David Sherman on Monday, June 11, 2007 at 20:09:36 :
In Reply to: Re: More Electrical Woes posted by M Fanoni on Monday, June 11, 2007 at 17:20:37 :
The worst that will happen if you adjust it too much is it will overcharge. I've noticed that most of the newer vehicles, with all their fancy electronics, tend to charge on the high side compared to old vehicles. What I would do is hang a voltmeter on it, right at the battery, and slowly rev up the motor. You should notice the voltage climb to a certain point and then as you go faster than that, the voltage will stay roughly constant and the arm of the voltage coil in the regulator will appear to vibrate slightly. You might or might not see a tiny spark at the contacts. Then, bend the tab to make the spring tighter, which will raise the voltage. Bend it only a tiny bit at a time. It won't take much to go up half a volt or so. Note that if you're below the RPMs where the contacts start vibrating, adjusting the spring won't do anything. The voltage coil is the one wound with fine wire. The current coil is wound with heavy wire. The cutout relay also has fine wire but has its contacts connected between the generator/alternator armature (output) and the battery, whereas the voltage and current coils have their contacts connected in the field circuit, possibly with some resistors mounted on the bottom side of the regulator.
You generally won't mess with the current coil. Its purpose is to keep the generator from working too hard and burning up if the battery is totally dead or there's a short in the system.
I picked 14.5 V rather arbitrarily, because that's usually a safe but enthusiastic charging level. 13.9 at maximum RPM is way too low.
One caveat is that cheap digital voltmeters ($10 Harbor Freight units, etc) are very unhappy with the choppy voltage produced by a mechanical regulator. Often if you check right at the battery posts, you can get a decent reading, but if the reading is way out of line or jumps all over, find an analog voltmeter or a good quality (Fluke) digital one. The better ones have filtering on the input to smooth out the spikes that the vibrating contacts cause.