A tale from the trenches.

A buddy of mine is a top-notch, veteran mechanic for a sprawling, multiline dealership owned by a corporation. Recently an out-of-state rider on a Honda GL1200 Gold Wing pulled up to the store, saying that the last shop he'd stopped at had diagnosed a smoked alternator as the reason for the battery going dead and could they install a new one pronto. "You bet" the service manager said, "we'll do a two-day air on the parts and get you on your way." Now, fried alternators in 1200 Wings are common but a huge job to fix because the engine has to come out. All said and done with parts, labor and tax the bill can be well over a grand.

My buddy is given the job and being no fool, he wants to see with his own eyes that the alternator is really dead. Squatting down with his voltmeter, he finds that it is, in fact, very much alive and putting out 90 volts AC. So he moves on to the only other culprit in the charging system that would prevent a battery from staying charged, the regulator/rectifier. Sure enough it's toast, and ...