AVR Drone Will No Longer Arm, Avionics Power Low

At some point during our flying today, our drone was damaged and would no longer arm. The students noticed that the small red wire that connects the pixhawk power module to the FC was pulled out of its connector. We replaced this wire with a new one, and ever since then, the drone is still not able to arm. We get the following error in Q ground control:

Preflight fail: Avionics power low

  • We have tested the 5v pins coming out of the power module and they both still read 5v.
  • We made sure to recalibrate the voltage sense in Q ground control. It reads the correct battery voltage and so does the GUI.
  • The FC does arm when we plug it in to power it via USB.

Any suggestions? Do we need a new flight controller or power module?

Here’s a view of Q ground control:

Are you competing this weekend?

When you say damaged did the drone crash?

We’re not competing this weekend.

I’m not sure what exactly happened because I wasn’t in the room. I know we had a crash earlier in the day where we broke a propeller guard. After that, the guard was replaced, the drone was checked over, and it was flown again later in the day.
This time, what I heard was it was flying okay, but the drone tipped sideways one time when picking up water, the propeller contacted a ball, and then all the motors stopped, which was when the problem began.

Sorry if that doesn’t help much; I wasn’t in the room for either of the incidents so I’m trying to piece together what I heard from the students.

Thanks for the info. What I’m wondering is if the battery was ejected, which would have yanked on the power module, and ultimately the connector going into the FC. So maybe a place to start is seeing if you can replace the entire cable between the power module and the FC. In the Pixhawk box are a bunch of spare cables, but I can’t guarantee there is one identical to the one that connects the power module. The fact that you can arm when plugged in via USB is encouraging. So either there is an issue with the cable or the power module. Also, what is your current battery voltage?

We did try one of the spare cables last night, but we can try another next meeting. The battery was at 15.8 volts.

I’m not sure the battery would have fallen out on this occasion since we have an additional battery strap that holds it really tight. But it’s possible there was damage over time from before we implemented that strap a month ago.