So here is my over-voltage issue --
So, here is my over-voltage issue.
First,
I have a Plane Power internally regulated alternator. 400 hrs.
I have an Odyssey PC-680 battery.
My voltage is indicated by the Dynon EMS D-120. I know that typically it reads a little bit low compared to a direct measurement of buss voltage, I have always assumed that's because of the small-gauge power wire to the D-120 causing a small voltage drop to the meter inside the D-120.
In the past, while cruising, the voltage indication typically floats around 14.7-14.8, with no accessories on other than the avionics buss, which powers the radio, transponder, Trutrak ADI-pilot, and Garmin 396. If I turn on strobes or nav lights, the voltage indication drops to 14.4 or so.
Last flight, I got an intermittent high-voltage alarm, with the indicated voltage floating around 14.9 to 15.2 (I have a 'yellow' warning set at 14.9 and 'red' alarm at 15.2. When I turned the strobes on, the indicated voltage dropped to about 14.4 and all appeared well.
Today on a ground run-up, I duplicated the high voltage alarm symptoms, with EVERYTHING turned off except the Dynon itself, so....
1) I don't believe it is noise, since everything was off
2) I checked the ground strap from the engine to the airframe
3) I checked the plug on the back of the PP alternator. (although I didn't pinch the contacts as Dan H. described)
4) the field circuit switch has been cycled a few times, so I doubt there is any sudden change in the resistance of the field circuit.
Note that the voltage is not pegged high, it is floating around from just below to just above 15V.
Questions:
is this an early sign of impending failure?
Can it hurt anything to have 15V on the buss? If so, I'll just keep some load on the system with the strobes or something. ( I know....I'm supposed to have the strobes on all the time anyway
)
Aside from buying a B&C alternator, should I do anything about it?
Note to those that frequently suggest switching to B&C, this is a non-trivial change because of the need to install an external regulator. Pretty significant surgery at this point to mount one on the bulkhead behind the panel, there's not really any room left there. And of course, figuring out and hacking into the existing wiring.