Could someone please check my log file and explain why it fell out of the sky

Hi All,

I was in loiter lifting a 1 lb (450gm) weight and it suddenly fell out of the sky.
I suspect an old battery (4200mah 35C), Flight controller, or m8n gps.
The FC is a Chinese pixracer r15.

Thank you.

Seems like a power cut to me.
Either your battery disconnected mid-flight, or your Bec stopped powering FC, or some solder came off,
did you inspect your build after the crash? was something burnt or anything obvious stating the above conditions

It seemed to me to be a power cut also. normally I would get a failsafe or error message but there was nothing
After the crash I had some broken legs to fix but did plug it in and it seemed all OK, I didn’t fly it though.
The battery is a couple of years old but not puffed. I will look at the wiring and see if I can find anything that’s loose or burnt.

Hi Colin-I would agree with @MindProbe that it was a catastrophic power failure not necessarily associated with the battery condition. It was supplying ~20A of current up until the log abruptly stopped probably signifying the FC lost power.

Hi Dave,
I had a good look at the power cables to the 4 in 1 ESCs but couldn’t see any shorts or loose connections. I put it altogether and could fly in Alt-Hold ok but had some trouble with loiter mode. I could only get 8 sats and it wouldn’t arm. On one occasion I got 10 sats and was able to arm, I just lifted it off the ground and it went haywire and flew into a flower bush. no harm done.
I changed the GPS/compass unit, recalibrated it through MP and I think the same thing would have happened if I had props on. I got “EKF primary changed” messages. I have also had “sensor lost” message at times. Could this be the fault of the FC? or maybe 2 faulty GPS units.

I think i have found the cause of the problem. The gps was mounted too close the powed cables and with increased current draw, the interference would have been greater and therefore gps failed. (I was in loiter)
I have installed a new gps mount which is further away from the noise, but need to recalibrate the gps when the weather is more suitable. Hopefully that will solve the problem.

That wouldn’t explain the abrupt cut in the log. That’s typically a power loss of the Flight Controller. It wouldn’t fall out of the sky if the GPS failed even in Loiter. It would just wander away or Failsafe and switch to Land mode if that’s what set.

Can you see what the vibratsion was like before the loss of power. I wonder if the power module is at fault? I also have a minim OSD pluged in running on 5 volts from the FC.
I am feeling uneasy about this build as i may never find the cause. I am using the Chinese pixracer r15 Flight controller and who knows how good or bad they are…
I do have a omnibus F4 pro FC working with arducopter i know it has limitations but maybe ok for my needs. You have had experence with these boards, what do you think?

Nothing unusual with vibes. I have one of those Clone version Pixracers and it has been performing well for years. Is this a new one you bought recently?

No I got it about 12 monthe ago, if you look back to May '21 in our previous chat you will ses our conversation about it.

Yea OK. Still looks like a power failure. All logged parameters just stop.

Can a power module go open circuit? ? Maybe i should replace it.
If there was a short circuit within the power module i would expect it to be still shorted. Wouldn’t you see a sudden rise in current in this case?
I think i can eliminate the battery going open.
Then there is the 4 in 1 esc, which i would think would be either good or bad.

I had one fail but that’s out of a bunch of them.

Could you also look for this log? Our drone fell out suddenly. We are suspecting of a battery problem or esc desync problem.

There was definitely a thrust loss but not sure where it started Motor 3 or 4. In any case they were commanded to max while the opposite was to Min. Not clear why.

Set these:

Would you say it could be a FC problem, because when I first inspected the crashed site , the FC lights were off and all was dead and it was only when I unplugged and reconnected it, all seemed good again.
The power module looks good no sign of any shorts or black spots, the cable is OK I connected to an other power module and that works fine.

Could be. The problem is there is nothing in the log that can suggest that. No trend on anything. I looked the IMU temps and that didn’t show anything.

Would a 4 in 1 esc fault like this? and then come right? ?

If it did I wouldn’t expect the FC to loose power. It’s sourced from the Power Module right?

It all seems to come back to a faulty power module.

I have replaced it and will upgrade to the latest arducopter software, recallabrate compass and gps etc. And do some more tests.