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Posted by David Sherman [72.47.9.228] on Wednesday, January 26, 2011 at 15:18:05 :
In Reply to: Well? posted by Will (in IL) [98.215.26.138] on Wednesday, January 26, 2011 at 14:31:19 :
It's definitely trying to charge. 8 volts on the field is telling the generator to work hard, and that's what the generator is doing. Shouldn't be "much" sparking. When a commutator of a motor or generator sparks significantly, in my experience it usually means shorted windings, not bad brushes, but it's always easiest to check the brushes first. That said, the generator is not causing the over-charging problem. Most likely the regulator the source of the problem. Clip a volt-meter to the battery and try pushing the voltage coil (the one with the fine wire) armature down with your finger to open up its points. The battery voltage should drop. Same with the current coil (the one with the heavy wire). If you have a 2-coil regulator, the coil that has both a heavy and a fine winding is the one you want. The other one disconnects the generator when the engine isn't running so as to avoid running the battery down. It doesn't do any regulating.
Once you've verified that manually opening the point of the voltage coil does indeed make the generator stop trying to charge, bend the lower tang that holds its spring very slightly up to loosen the tension on the spring. This means it takes less voltage in the coil to pull the points open. The adjustment is subtle and you'll probably need to go back and forth a few times to get it right. Be careful not to short against any grounds when bending that tang, since it has battery voltage on it. If you can get the charging voltage into the 14-14.5 volt range, call it good. The mechanical regulators won't hold better than half a volt one way or the other. I would aim for no higher than 14.5 at max RPM with a fully charged battery.
If you don't want to mess with it, just buy a new regulator. On the other hand, attempting to adjust it yourself will give you a new skill and might show you if something else in the system is wrong.
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