Why does it crash so much?

Hi everyone
My drone crashed at the most random times, like when I send it out to do a mission and a few seconds after the mission start I decide to switch to stabilize mode and fly back to Launch, when switch it just does a flip and fall down, I am so confused with this.

Here is n log file of a crash that happend just before landing, it was descending and about 3m above ground it just almost started falling : https://filegooi.co.za/v002/getfile/62179180cb0185a7be05931fa48e8002/2020-11-13+15-53-09.log?fbclid=IwAR2guT_wLr8Ehcteh-1IF-8fWcJ4zpPnsCOUjgPN9RcR7qmRhLhWqW-p4wo

Please can someone analyze this log file so I can figure out why the heck it crashed again

Hi Marnus! It seems you have a problem with your motor 1, maybe the motor or the ESC is bad because it reaches the maximum while the others motors are normal and trying to compensate the failure. So for me you had a desync problem.

Also the tuning of the roll axis can be better because it some cases the Roll doesn’t follow the desired Roll very well.

Thank you @davidae! I have had this problem for a while, I have checked to wiring and looks okay. Is there a way to determine if it is the motor or ESC without swopping with other motors on the drone? This is my final year project and I will be demonstrating in a week or so, I am in South Africa so parts and spares are view difficult to find. Any help would be appreciated greatly.

@davidae can I use another brand 20A esc ? That is all I would be able to find here

To test the motors disconnect them from the ESC and make them spinning manually with a drill for example, and see the AC voltage betwen two of the three wires, and of course check every combination, the voltage of all combinations must be the same, if not, then you have a coil broken. (https://gesrepair.com/test-brushless-motor/)

If the motor is ok, then your problem is the ESC and that is more difficult to find if it only fails sometimes. My recommendation would be change that ESC by the same model. I don’t recommend you to change it for other brand, but of course you can change the four ESC if you can afford it.

Thank you @davidae! I did some research and found that my motor mount was a bit loose, can this be the cause? Can you maybe see in the log file vibration or anything that can prove that the loose motor mount could’ve caused this?

Your vibration levels are a bit high but in the limits of under 30, that is not the cause of your problem.

But why do you think this only happens 1/10 mission, using the exact motors with exact esc’s.

Then I start to think it is a temperature factor that is affecting the “bad esc”. Is there a way in mission planner to limit excessive current drawn from esc like slowing down accelerations and so on?

I went over my wiring today and found a spot where my esc Vcc and GRD had damaged isolation, maybe they were shorting?

I also calibrated the esc’s today and what happens is when I strap the drone done and yerk the throttle excessively, the esc’s loose sync and stall at high throttle range. Any feedback on this? Please see video