My RV12 is equipped with dual Dynon Skyview HDXs ("SVs"). Until recently, the Amps and Volts displayed on the SVs were exactly what they were supposed to be. Now though the SVs display negative Amps -- anywhere from -4 to -12 Amps, depending on how many of the plane's components I've turned on -- and declining Volts.

The plane has a Rotax 912ULS engine, and many planes with that engine have this identical battery charge issue. My mechanic has done all of the things recommended in other threads here on Rotax-Owner.com 
- He secured the connections to the Ducati Rectifier/Regulator.
- He replaced the Rectifier/Regular with a new one, because the old one had blisters on its back.
- He tested the voltage output of the stator and of the new Rectifier Regulator, both of which were what they should be.
- He improved the grounding of the Rectifier/Regulator by sanding the firewall to which it is bolted; and he added a ground wire attached to the battery's negative terminal.
- He changed the Rectifier/Regulator again, in case the first new one was defective right out of the box.
- He charged the plane's Odyssey PC680 battery. And I replaced that battery with a brand new Odyssey PC680 battery.

None of these things helped. The engine starts immediately and runs smoothly. But:

- The Skyviews still display negative Amps and declining Volts.
- Also, both SVs turn on as soon as the Master switch is turned on, but after just a few moments, the co-pilot side SV blinks off and reboots.
- Finally, the digital checklist I added to the SVs no longer stays on, the way it used to. Now, after a short time, the checklist blinks off and is replaced by the moving map (which is the default item for the right half of my displays).

The only change to my Skyview setup that I've made is that shortly before the battery charge problem began, I installed Dynon WiFi Adapters. They worked fine for a couple of flights, and then my iPad Mini began dropping the WiFi signal.

I now wonder whether my problem is with the Dynon Engine Monitoring System, rather than the plane's charging circuit. That is, I wonder whether the failure of the old Rectifier/Regulator -- or something else -- damaged the circuit that senses, reads and displays Amps and Volts, so the SVs now erroneously display negative Amps and declining Volts.

Any thoughts about what my problem might be, or what to do next, would be deeply appreciated. Right now, I'm the stressed owner of a handsome assembly of used airplane parts, without a clue about what I can do to turn those parts back into the wonderful airplane it used to be.

  • Re: No Joy with Diagnosis of Negative Amps & Declining Volts

    by » 2 weeks ago


    If it were me I would attach a separate voltmeter to the bus to see if there is a problem with your Skyview's voltage monitoring or a problem with the charging system.


  • Re: No Joy with Diagnosis of Negative Amps & Declining Volts

    by » 2 weeks ago


    Ken Ryan wrote:

    If it were me I would attach a separate voltmeter to the bus to see if there is a problem with your Skyview's voltage monitoring or a problem with the charging system.

    I've done what you suggested. With the engine off, the electric fuel pump off (i.e., the circuit breaker removed), and the avionics off, I got these readings on the multimeter:

    With both Skyviews on and the Skyview showing 11.9 battery volts:
    C 1.18 volts
    R 11.9 volts
    B+ 11.9 volts
    Battery 11.94 volts

    With only the pilot-side Skyview on (co-pilot-side off) and the Skyview showing 12.00 volts:
    C 1.16 volts
    R 11.98 volts
    B+ 11.99 volts
    Battery 12.00 volts

    With the engine off, I also measured the resistance between the two yellow wires that plug into the G pins; and, after several moments of bouncing around, the multimeter showed a resistance of 0.2 ohms. There was no reading between each yellow wire and a ground.

    With the engine off and the avionics off, the Skyview displayed these readings.
    With the electric fuel pump off (i.e., the circuit breaker removed)
    -4 amps with only the pilot-side Skyview on,
    -5 amps with both Skyviews on,
    -6 amps with both Skyviews on and the Dynon WiFi Adapters plugged.
    With the electric fuel pump on (circuit breaker plugged in)
    -7 amps with two displays on and the WiFi Adapters plugged in.


  • Re: No Joy with Diagnosis of Negative Amps & Declining Volts

    by » 2 weeks ago


    Is the the battery charging/positive amps at higher RPM? The charging system that comes with the Rotax 912 only really works good at the higher RPM's It is not like your cars charging system. Most of the time the battery starts out for a flight not fully charged (unless it was on a trickle charger/charged), then it has to start the motor then it has to support the avionics while you taxi to the runway and let the engine warm up all the while the battery is discharging. Then when you go to take off power and cruise RPM the charging circuit has to recharge the battery and run all the avionics which puts a lot of stress/overloads the charging circuit particularly the connectors at the regulator. If your mechanic just went thru the charging system then everything is probably OK. Always try to start off with a fully charged battery then only turn on avionics as you need it and before and after landing start shutting equipment down as soon as possible. Practice battery energy management because the charging system only really works at the higher RPM's.


  • Re: No Joy with Diagnosis of Negative Amps & Declining Volts

    by » 2 weeks ago


    Related image


  • Re: No Joy with Diagnosis of Negative Amps & Declining Volts

    by » 2 weeks ago


    Garrett Wysocki wrote:

    Is the the battery charging/positive amps at higher RPM? The charging system that comes with the Rotax 912 only really works good at the higher RPM's It is not like your cars charging system. Most of the time the battery starts out for a flight not fully charged (unless it was on a trickle charger/charged), then it has to start the motor then it has to support the avionics while you taxi to the runway and let the engine warm up all the while the battery is discharging. Then when you go to take off power and cruise RPM the charging circuit has to recharge the battery and run all the avionics which puts a lot of stress/overloads the charging circuit particularly the connectors at the regulator. If your mechanic just went thru the charging system then everything is probably OK. Always try to start off with a fully charged battery then only turn on avionics as you need it and before and after landing start shutting equipment down as soon as possible. Practice battery energy management because the charging system only really works at the higher RPM's.

    I haven't flown the plane, or operated it at RPMs greater than 2500, since the original Ducati Rectifier/Regulator was replaced. I did fly it just before the Ducati was replaced, at about 5000 RPM; but amps were negative and volts declined even during that flight. Of course, that flight was with a bad Ducati. I will try a run-up at 5000 RPM tomorrow to see whether that gives me positive amps and increasing volts. I'd like to be optimistic, but I'm not, because before this problem descended on me, I got positive amps as soon as I started the engine and while taxiing at 2500 RPM until the oil temperature reached 120.


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