Its true, an unregulated 6 volt generator will put out 16-20 volts with no load.However, when under load, like the lights,the generator will not exceed 12 volts at normal speeds.Of course you need 14 volts to keep the battery properly charged.This trick works just OK on tractors. They have no load except for the ignition and the engine runs at a constant speed most of the time.Its also common practice on old British motorcycles to bump up a 6 volt generator with a regulator change.Again, it works just ok if you have little load and keep the engine reved up.The difference between 12 and 6 volt generators is in the number and guage of the wire windings in the armature and or field coils
