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USB + LiPo power for APM2?

Posted by Alex on May 6, 2012 at 12:51am

This question has been asked before but never answered as far as I could determine, and it's not in the manual:

Is it OK to plug in the USB cable to the APM2 while it is powered up with a LiPo?

The manual addresses powering up the RC receiver separately from the servos but that is not what I'm asking.  I want to configure the APM2 with the MP software while it's in the aircraft with the USB.  If I do not connect the LiPo also, the digital servo will consume a lot of current, probably too much for the USB to supply.  So is it safe to have power from both the USB and LiPo at the same time or will it break something?

Thanks

Alex

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Replies

  • James May 7, 2012 at 5:59am

    the danger is with the usb bootloader, as it can (and does) ocasionally send an out of range signal to the motor output pins.

     

    it seems a bit off that after reading the warning a dozen times in the manual not to connect USB and main power at the same time, that one of the first things you need to do is to test motors and for that you need to connect USB and main power at the same time.

     

    there are two real dangers:

    • one or more motors may spin up (very dangerous if they have props on) 
    • one or more mators may "shudder" violently back and forth emitting smoke (a huge pain if you burn a motor out)

    so, ocasionally we do need to connect both lipo and USB - my solution is to disconnect the ESC signal leads while i have both usb and lipo connected.  if you also need to test motors i think the correct procedure would be to take the props off, connect USB, connect lipo and finally connect the ESC leads - just touch them to the pins first and if any of the motors do anything strange disconnect straight away.

     

    regards,

     

    james

     

  • Asaak May 7, 2012 at 5:42am

    Same here! I want to set-up the APM2.0 board. I plugged the mini-usb to the apm2.0 so I can start mission planner and start the configuration. However When I plug rc receiver to the inputs, nothing happens. It seems that it is not receiving any voltage so, Should I connect the motor connector ( which is the one carrying the voltage from the ESC ) to the output channel of motor??? I didn't touch the factory configuration regarding power supply for the APM.

    thanks!

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