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  • Re: Backup battery switch?

    by » 4 years ago


    I now know how it is all connected and why it is not working correctly.

    {option}

    As you can see there are some minor mistakes and one BIG one.

    1. F2 is a 25A instead of 30A. If the generator is 30A, it should not be 25A.
    2. The battery backup switch is permanently connected to the battery.
    3. F1 is missing in the wire to the backup battery switch.
    4. The 12V net is connected to pin 2 instead of pin 3 in connector X3.

    This big mistake is "hidden" by using the special checklist where the backup battery switch need to be turned off at start of the engine and then on right after. That way some power is delivered from X3-1 to the 12V net and the battery. My guess is that this connection is going to ALT-A. This fits the observation I did when we started the second time. Only after the aux fuel pump was turned off, it started charging the battery.

    Beside this, it is really scary to see that almost all the red 12V wires are melted. That includes the two start power wires. I do not quite understand this. The only way for a big current to flow is from X3-3 through the start power switch, back through F2, to the 12V net and then to the battery. But when should that have happened. We did not fly with the switch in "start position", and why do the wires melt before F2 blows at 25 amps!

    I'm not able to see that it is really AWG12 wires.

    I have one questions for you. Is the X3 connector delivered WITH wires, or as a bare connector where you mount your own cable?
    I need to know if X3 need to be changed to a new with wires or if the wires can be changed inside.

    We are very much thinking about changing to teflon covered AWG12 wires to avoid a fire in the plane in the future. For me this was a kind of "close call" and if we would have had a fire in a all carbon fiber airplane, we would have died because of this.

    Thanks all for helping with this problem.

    Kind regards, Claus

  • Re: Backup battery switch?

    by » 4 years ago


    I did not examine your diagram but to answer the X3 question: it is supplied as a seperate pieces and needs to be assembled by the aircraft manufacture.
    see attached training material (Draft only, not peer reviewed)
    X3info.pdf (You do not have access to download this file.)

  • Re: Backup battery switch?

    by » 4 years ago


    Thanks Rob

    It looks like a very nice document, but at the same time very hard to attach new wires to the X3 connector. It looks like you need new pins, and the crimp tool.

  • Re: Backup battery switch?

    by » 4 years ago


    yes, you will need new pins, the extraction tool and crimp tool.

  • Re: Backup battery switch?

    by » 4 years ago


    Hi guys. I could really, really use an expert response to this now.

    I have been discussing back and forth with the supplier, and now he sent me the diagram they got certified on. Pin 2 and 3 is swapped from Rotax!!!

    {option}

    I have to agree with the supplier. They followed the diagram from Rotax, and that does looks so wrong in so many ways. How could this ever supply any power to the plane? The backup battery switch is supposed to be off (in my plane it needs to be on, and the warning lamp is a GREEN LED!). The fuse is indeed 25A, and only one of them. Even the starter motor is wired through the master switch!!!
    How can Rotax certify something that is so wrong?

    HELP....

    Kind regards, Claus

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