over-voltage

[John Hoffman]

No over voltage in 10 yrs. now. Did have some intermittent low voltage over the years. It would show one alternator off and voltage would drop a little. That was fixed a year ago when an alternator drive failed in the rear engine. I take some credit for finding out how to adjust the voltage regulator and working with an A&P adjust it - problem is gone. I got to believe that the droping on and off due to poor voltage adjustment helped fail the alternator drive.

[Dale Campbell]

Hi,
This is good information. I also have had both circuit breakers pop. In the last 100 hours I had 2 overvolage problems. One was on take off after a 2 hour flite to Lake George,NY. I push the breaker in and turned the alt. switch back on and it happened again. Of course you loose all electric power. I waited 1 minute and reset breaker and this time did not turn on alternators. Electric power came back and I flew for 30 minutes just on battery. I told ATC I had a electric problem and if I lost radio or transponder I would use a portable com I had on board. After 30 minutes they said the transponder was failing. I than turned on 1 alternator and the breaker did not pop. After 5 minutes I turned on the other and all was OK.
I told my AP and he looked and found nothing. That was a year ago. I will pull the breaker panel and look for the problem you had. Thank you, Dale Campbell

[edasmus]

Hi Dale,

It sounds as if your system is somewhat different than mine. By all means I would go ahead and check behind the circuit breaker panel but for what it is worth, my problem never caused any circuit breakers to trip. The only symptom was the over-voltage sensor shutting down the alternators which is exactly what the system is designed to do. To reset the system requires turning off the alternator switches and turning off the master switch for a few seconds followed by turning the master and alternator switches back on to restore normal operation of the electrical system. Assuming no problems, the system should obviously continue to function which was not the case for me until the problem behind the circuit breaker panel was uncovered.

Good Luck.

[Dale Campbell]

I did shut every thing down and wait, as you mentioned, and followed the power back up procedure. But, as soon as I put the first alternator back on, the breaker poped again. That morning when I started my flight, I had to get a battery jump to get it started. I did not fly for 6 weeks and the battery was dead. I though when it started to charge,it over charged.
Because it was 2 hours into flight before the over voltage light came on and breaker poped.
After I drained down the battery by not turning on alternators for a half hour the battery was no longer over charged and when I turned alternators back on after that all was normal again. Problem never came back, so I forgot about it. I did purchase a battery charger with maintance feature that GMAS recommended on this site and I leave that on now when not flying. It seems to work great. Dale

[edasmus]

Well folks, just a brief note. Almost two years and over 200 hours since I last posted on this thread about my "over-voltage" tails of woe and the ugly beast has reappeared in my Skymaster. Same symptoms as last time. Random "popping" in my headset and on the last flight during the landing gear up cycle, the over-voltage sensor decided it was time to shut down the alternators. After resetting the over-voltage relay per procedure in flight, for the next 20 minutes, the beast caused no further problems. The problem has appeared on my last two short flights (about an hour total) with the over-voltage protection tripping on the last flight.

Of course, the first place I went was behind my circuit breaker panel and all was in perfect condition. Now the airplane is all opened up looking for evidence of a short circuit and arcing. Myself, a friend, and my IA have been everywhere you can be within reason without completely dismantling the electrical system and can see nothing obvious.

The plan now is to put the airplane together enough to go fly with my IA early next week and hope the beast shows it's ugly head while my IA intends to be crawling around the cabin looking for sparks while I try to isolate the issue. Currently, the "haystack" so to speak is quite large. I'll keep you posted.

Any suggestions?

Ed

[stackj]

Ed...

YOU are the same age as my Skymaster. I wish I was in that age group!

[edasmus]

Thanks Jim....Yes, it is kinda funny that me and my airplane are nearly the same age. In April of 2009 I had the opportunity to fly my Skymaster down to Springfield, MO to meet the first owner back in the early 1970's. I actually met him through this website. Anyway, his name is Paul and he is a super nice man. He gave me photo copies of his logbook that noted the hours that he flew the airplane, as well as the original invoice that showed all the options the plane had when it was new, and lastly a photo of the airplane when it was new. It was very cool and the fact that I was in the 1st grade at the time makes it even more special. I can clearly remember being in the 1st grade.

As for my electrical issues, I just returned home after flying with my IA and fortunately the electrical system misbehaved immediately upon gear retraction on take-off. He had his volt meter attached to the buss to monitor exactly what was happening. One thing that was clear before we even departed is that the alternators are set too high. They are making 30.5 to 31 volts and I guess it should be more like 28 to 28.5 volts. The fact that the voltage is so high leaves very little margin to the 32 volt limit for the over-voltage sensor during normal voltage fluctuations. He also suspects something is up with the alternator field circuit breakers but at this point I am not exactly sure what it all means. He feels the system is enough out of spec that after making some adjustments he wants me to fly some more and see how it goes. He cannot rule out arcing somewhere in the system similar to what caused the beginning of this thread but after searching the last 4 days and finding nothing he is going to make these adjustments and we will see what happens. Stay tuned.

Ed