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On a recent cross-country flight in an RV-12 ( Skyview installation), the voltmeter started spiking between 14.4 volts and 15.8 volts. I Landed as soon as possible. Lockwood Aviation tech support thought it was either the regulator/rectifier or perhaps the R, B+ or C wire. I was carrying an extra regulator/rectifier due to their notorious reputation. When I inspected the old regulator and the connectors, there were no signs of overheating. Nevertheless, I replaced it with the new one. It appeared to work on the ground. When I took off again, it worked for about 1 hour and then started spiking again.

From other things I have read, I suspect that the C wire is not seating properly and when I connected the new regulator, it seated temporarily but become loose again in flight.

I would appreciate any comments on this. We have not been able to get back out to the aircraft to check this connector.

Also, I am trying to figure out exactly what the C connector does. The other four I was able to trace on the schematic, however, the C wire appears to get connected to the Skyview, but I cannot tell what its function is.

Thanks for any comments.
  • Re: Regulator/Rectifier

    by » 7 years ago


    I had the same problem, I have then removed the original connector, replaced it with individual inox lug connectors with heat shrink and since, no problem.

  • Re: Regulator/Rectifier

    by » 7 years ago


    The regulator C pin is the control input. It senses system voltage (battery voltage, plus regulator output, minus system load) to turn the regulator on and off. If the voltage to this pin is above three volts there is enough power to turn ON the regulator, once the pin voltage exceeds 14 volts the output is turned OFF.

    On the RV12, the C pin is connected to the main BUS through the second pole of the master switch.

    The typical failure mode for a Rotax regulator is reduced output, or no output, so your regulator is likely good. A resistive connection in the C pin circuit will give you an overvoltage condition because the regulator is trying to compensate for the voltage drop seen on the sense pin.

    As a side note, the Amp Faston connector is rated for 10 mating cycles....a "knock-off" part may be of lesser quality.

  • Re: Regulator/Rectifier

    by » 7 years ago


    Thank you for your response. I have never heard of a inox lug connector.

    Do you have a source for that? I would like to see what one looks like and how it compares to the connector I am currently using.

    It turned out that the C connector was not seated properly in the connector housing and it appears to be working correctly now but I am interested in better solutions.

    Thank you

  • Re: Regulator/Rectifier

    by » 7 years ago


    Mike,
    Thank you for the excellent explanation.
    It turned out that the C pin was not seated properly in the connector housing. We re-inserted it and after almost two hours of flying, everything appears to be OK.
    I am still confused and concerned on one point-
    Did we really have a overvoltage condition or did our voltmeter just indicate an overvoltage condition?
    The reason I am trying to clarify this is that I am concerned that I might have damaged the battery or electrical system.
    When I was trying to figure this out, I contacted Odyssey battery to get their perspective. They felt that if I had a real overvoltage situation, then the battery would have failed. They said the battery has a built in venting system so it will not explode, however, we would have smelled an odor like rotten eggs. I inspected the battery. It appeared normal plus there was no odor. Furthermore, after we fixed the problem, it had no problem starting the aircraft. Maybe the battery can handle more volts than they recommend (15 volts max.)

    Do you have any thoughts on this?

    You have been a tremendous help.

    Thank you.

    Bob

  • Re: Regulator/Rectifier

    by » 7 years ago


    Bob,
    Your welcome.

    With a resistive connection on the C pin you did have an over-voltage condition. The displayed voltages and alarms were accurate. But I wouldn't worry about it, I doubt anything was damaged. Most of your expensive avionics devices are designed for 12 - 28 volt operation, so no problem here. I agree with the people at Odyssey, the battery is robust, its not going to catch fire or melt down, worst case is you may have shortened its life, but I doubt it. The only thing I can think of that may have caused the smell are the two cooling fans under the panel. These fans use stepping motors and are rated for 12 volts, they may not tolerate an over voltage, just a guess here. But easy to check, turn the master on and see if they spin. Good luck.

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