Here's the story: Less than a year ago I had to replace my interav alternator. Now I began getting an intermittent discharge light. My mechanic removed the two-piece voltage regulator and over voltage relay system with the integrated Plane Power regulator/over voltage system (and I'm told taking care to retire the system correctly) Now, however, instead of a discharge light I'm getting an intermittent over voltage light. At the same time, there is a high-pitched whine over the radios, the panel lights dim and brighten, and the electric engine gauges jump wildly. My mechanic consulted the folks at Plane Power, who surmised there was some sort of resistance in the system causing it to malfunction. Accordingly, my mechanic replaced the master switch. No help. If, as I suspect, the voltage at the alternator equals that at the electrical bus, my mechanic has run out ideas.

Has anyone else had a similar experience mixing and matching alternator and regulator/over voltage relays?

Disparate in Boston

Tom, this is just a guess, but it sounds like you have a ground problem. The most simple to diagnose is checking the
battery ground cable if its dirty or loose as it can give this problem. Then check the ground from the alternator to the engine block, then the engine ground strap then the ground wire to the voltage relay. if all are good you might have a bad diode in your alternator or bad capacitor, both of which can be checked on the bench... but because you are getting intermittent over voltage from the alt I really think you have a ground problem. Kinda makes since if its a ground problem, the voltage regulator will see a low voltage because of the bad ground and bumps the signal to the alt field to increase the voltage. the ground vibrates to a good connection and then the reg says whoa and lowers the voltage... causing the varying light intensities. The whine is a very good indication of a poor ground as well.

Check the ground and good luck,
Gary

Thanks, Gary

Not being a mechanic, or even mechanical, your advice is deeply appreciated.