Common Ground and Power conections

I am currently using the Pixhawk 2.4.8. I can’t seem to find the answers to following power wiring questions…

  1. Is there a common ground between the Servo Rail ground and the Power connector(6-pin connector) ground?
  2. I understand that +5V can be applied to the Servo rail to power the Pixhawk. Let’s assume 5.3VDC is attached to the servo rail power input, will that +5.3VDC go through a voltage regulator and reduce the power to 5VDC?
  3. The 6 pin power connector has two +5VDC pins. Do both need to be connected or is only one necessary?


  1. Yes. But you can whip out a multimeter and check it as well. :slight_smile:
  2. With 2.4.8 you milage will vary, since 2.4.8 pixhawks are the common name for cheap, cost optimized clones (there were never an official 2.4.8 release of the HW). Usually they spare the power management chip and use a simple diode logic for multiple power sources, which sometimes does not play good with power from the servo rail (intend to release the magic smoke). If you have a real pixhawk (2.4.6, with a LTC4417 power path selector IC) then you can add backup power from the servo rail with a zener diode as it said in the docs (
  3. There are two gnd and two +5 connected together because the df13 connector pins are not rated for 1A. You should connect both.
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I agree with Andras regarding powering the servo rail on a 2.4.8. While you have your multimeter out check the voltage on the servo rail. USB connected is all you need. Hmm, there is ~4.5 volts there… Not so on a 2.4.6 (I have some of each) with proper power management.