Royal duel battery problem problem

  • I just installed a new Royal.

    The installation was fine. All checked.

    Was making final adjustments to the setup when the following happened.

    When Battery 1 was switched off via the switch the PB drove the L aileron servo to max deflect (ripping it from the housing) No control to any surface.

    The only way to stop this was to unplug Battery 2

    Upon trouble shooting the following was discovered.


    Plug in Battery 1, Power box comes on but no green light from the switch.

    Battery 2 two system works fine.


    Plug in Battery 2 and switch on the unit then plug in battery one (which shows power without green light) then 'switch on battery 1' All is fine two green lights on the switch.

    Now test the fail safe by disconnect battery 2 and the powerbox drives sometimes the elevator L to max or sometimes the aileron L to full and you don’t get redundant power you loose full control.


    You cannot switch off the powerbox with batt 1 connected and when you leave the system to battery 1 you have no control and but also one servo is driven to max

    Any suggestions....?

  • Yes. But it seams to be dumping any signal from the tx and then driving servos to some kind of default setting which unfortunately for the aileron was out of the range of the housing. One would expect it to just leave the servos alone with a power fault.

    Anyway will be with you tomorrow so you can have a look. Will be interesting to know what is wrong

  • Hello 5onic,

    I checked your unit today and found out that batt. 1 was connected with reversed polarity. I replaced the two regulators and fully checked the unit. Everything is fine now. Our sales department will contact you once your unit is ready for sending back to you, as it is on our test circle at the moment.

  • Thanks very much for responding so fast.

    I am always very careful so please help me understand what went wrong as I do not wish this to happen again.

    I used the same duel battery setup all along without problems until.....

    I used a single stand in battery for batt 1. It was 2 cell LiFe instead of LiPo.

    It was connected via a powerbox JR to MPX convertor.

    I have check the battery and also the powerbox MPX/JR connector for correct polarisation so that is ruled out. (also it cannot be reversed polarised at the JR connector)

    This only leaves the possibility that the MPX was put into the power box backwards. Is this possible with a bit of force?

    Can you please check on the powerbox unit where the connector goes in on Batt one to see if there is any sign the MPX was put in backwards, or am I missing something here?


  • Hello 5onic,

    if you try to connect the MPX connectors wrong way, under some circumstances you could make a connection. This will result in blown regulators.

    Maybe that happened. Please also double check your batteries for polarization, just to be sure everything is correct.

  • Thanks Alexander,

    I double checked the batteries with a voltmeter for +ve polarisation. They are all ok so I will assume it was an MPX connection the wrong way around.

    Thanks for your help and speedy service.

    Have a great weekend...