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Posted by D Sherman [72.47.153.24] on Sunday, May 20, 2012 at 17:21:27 :
In Reply to: voltage reg./gen. problems 6-volt posted by JET [75.53.129.55] on Sunday, May 20, 2012 at 16:05:26 :
I assume you're talking about regulator points rather than ignition points here. You can learn a lot by watching the regulator with the cover off, with a voltmeter attached to the battery, working the throttle by hand. Your regulator should have 3 coils in it, a "voltage" coil wound with fine wire, a "current" coil wound with very heavy wire, and a "cutout" coil that pulls in whenever the generator is running fact enough to potentially charge the battery. The cutout coil closes its points when it pulls down. The other two open their points when they close down.
When the battery is well charged and the engine is revved up, you should see the current points totally closed, and the voltage points chattering lightly. Pushing the armature down (opening the points) by hand (it won't shock you), should result in the battery voltage dropping to a "float" level of 6.3V or so. Pulling the armature up so the points are closed all the time should "overcharge" the battery to more than 7.2 volts. Often you can hear a difference in the engine RPM when you open or close the points.
Now on the current coil, if your problem is that it's not opening up, push the armature down to force the points open. That should have the same effect as opening the voltage points -- it should basically cut the generator out and drop the battery voltage to a float level. If it does, then you probably just need to adjust the tension on the current coil spring. If it does not, something else is wrong. Maybe the whole shebang is mis-wired or something has shorted out in the regulator or elsewhere.
Another useful place to hang a voltmeter is on the field wire to the generator. If the field voltage is close to the battery voltage, the generator is running at maximum output. If you don't think it should be doing that (because the battery is fully charged), figure out why. Normally, the field voltage will jitter around somewhere in the middle of the battery voltage range. This is where an analog meter is better because it gives you a steadier reading, as the regulator points vibrate open and closed. The resistors on the bottom side of the regulator are there to limit the field current. Depending on the design, they cut in or or depending on whether the points are open or closed. Often they get burned out (open) or mechanically broken, which wreaks havoc with the charging, sometimes in non-obvious ways.
An electromechanical regulator is really a pretty simple and comprehensible thing once you learn how it works, and by using a voltmeter or two and manually opening and closing the various sets of points, you can learn a lot about what's going on. Are you sure your voltage or current coil points aren't simply welded/stuck closed? I've seen that happen due to a temporary short in the field circuit. Sometimes you can pry them apart with no serious harm done.
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