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Posted by David Sherman on Thursday, March 19, 2009 at 03:43:41 :
In Reply to: Generator and Regulator Compatability Question posted by Dave Horvath on Wednesday, March 18, 2009 at 22:32:36 :
I can answer a couple of the questions, but not all. The smaller pulley will make it spin faster. Since generator output is directly proportional to speed (multiplied by field current) this is usually a good thing because it will make more electricity at lower RPMs. The only problem is if you spin it too fast, it will fly apart. Generators can't be spun near as fast as alternators can, because the slotted commutator can't withstand as much centrifugal force as the solid slip rings on an alternator. That's why alternators can be made smaller for the same power output, if you spin them faster. You'll have to decide of the higher speed is safe.
As for adjustments, a 3-coil electromechanical regulator can be adjusted to limit at the maximum safe output of your generator. The coil with the very heavy winding is the current coil. You adjust it by bending the spring tab just like you'd adjust the voltage coil. You'll need to run the generator at full speed into a heavy load in order to do the adjustment. If you don't have a good test set up, better to take it to an old-fashioned auto electric shop that still has an old guy who can put it on his test set and adjust it. 2-coil regulators may regulate current in combination with voltage via one coil that has a heavy winding and a light one, but the voltage and current limits aren't independently adjustable. All the schematics I've seen of solid-state regulators don't include any current-limiting feature, so the engineers must figure the modern alternators are safe to not burn up even if loaded with a dead short.