Pixhawk - Back-Up Power via USB port


I'm building a hybrid UAV with a Pixhawk flight controller for use in a competition. As far as i've understood a requirement of the competition is to have a back-up power supply for the flight controller ONLY (does not power any actuators). I think this is to maintain contact with the UAV until it crashes if main power is lost.

My question is:

Can i use a small 2S (~7V) battery regulated to 5V with a BEC into the USB port while powering the pixhawk normally via main Power Port and then the Motors/Actuators via ESC/BEC's on the Servo Rail?

Second question, is there any difference between the vertical facing "USB" port and the side microUSB port on the Pixhawk?

My understanding is the pixhawk will have to loose power to both Main Power and Servo Rail before it uses the USB power, so i feel like it should be fine. However, in the past i have blown a 3.3V regulator on a Pixhawk and i suspect i did it by powering the main port and USB port at the same time while calibrating things. Not sure on this.


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  • to answer your question: yes, the USB DF-13 and micro-USB connector are directly connected.  - so you can get power redundancy from any of those.  

    The redundancy is for Pixhawk, recieiver, telemetry radio...  the USB power will not be used to power servo rail.   Power redundancy is to ensure safe/reliable power for electronics, - and allow more noisy power from multiple BEC's on the servo rail.   - not to protect from depleted batteries.

    The scorpion thingy (an expesive 5v BEC with 2s 500mAh battery) is not something you need.  - unless you plan to drain the main battery hoping that 500mAh extra will save the day.   

    • Thank You Andre :)

      Just what i needed to know.

  • Take a look at this- works really great is independent and light:



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