Redundant power not working as I expected (howto?)

Pixhawk 2.4

  • I connected power module, and applied +5,3v to servo rail.
  • on removal of power module-power, all lights on Pixhawk (and safety switch) go out, except for IO PWR Led (green)

I checked with schematics, and verified that these are the two sources that are used.

I had the same experience. The power fail over is not working IMO.


Here is how to connect: … m_the_ESCs

Also a related post:


Here is how to connect: … m_the_ESCs

Also a related post:

Thanks. Does the battery fail safe have to be set for the backup power feature to work? My understanding was that it was in the FW or hard wired to do automatically.

Yes that’s how I connected, BTW, I checked the schematics, and can confirm that it’s not software-dependent.

Also, I got it working, It seems that I must have had one of the lab PSU’s below 5v or 5.0v is borderline
Will test much more and let you know.

THe failover is working as designed.

The LTC®4417 connects one of three valid power supplies
to a common output based on priority. Priority is defined
by pin assignment, with V1 assigned the highest priority
and V3 the lowest priority. A power supply is defined as
valid when its voltage has been within its overvoltage (OV)
and undervoltage (UV) window continuously for at least
256ms. If the highest priority valid input falls out of the
OV/UV window, the channel is immediately disconnected
and the next highest priority valid input is connected to the
common output.

retested right now with lab PSU connected to servo rail set at 5.000v max 280mA - and it worked exactly as expected, I honestly do not know how I managed to not get it working the first time I tested this highly appreciated feature.

Mine works as well. I’m not at all sure what the issue was initially but it seems to be working fine at the moment.