I just recovered a quadcopter that had a crash and I have to analyze what happened.
I think I found it, but I would like a second opinion.
4S LIHV battery (max load 17.2 volts)
ESC 4 in 1 T Motor 55A
By analyzing the logs of the flight during which there was a crash (log 2022-08-10 17-03-43), we see that the battery failed. At first, the battery was only charged to 16.76 volts instead of 17.2 volts, and after several minutes of flight, the battery voltage collapsed, leading to the crash.
For having discussed with the user, he told me that the battery was swollen, confirming what I thought.
The drone showed little damage after the crash.
The user replaced the battery and when arming the drone (log 2022-08-12 10-37-36), the right rear motor (n°4) seems “out of sync” and the drone which was placed on the ground vibrated a lot. Unable to disarm the drone, he had to disconnect the battery. The motor does not appear to be mechanically damaged.
I picked up the drone for testing. I removed the propellers and put the drone into operation. Without propellers, the motors visually seemed to be working fine (Loiter flight mode), but after a few seconds I got a “Potential Thrust Loss” alarm, which seemed logical to me, since there was no propeller, but impossible to disarm the drone (with the throttle stick at the bottom left), I had to disconnect the battery.
Could a battery failure have caused a synchronization fault on an ESC ?
Why can’t the drone be disarmed ?
Is there a way to know the number of flight hours of the drone with the logs ?
Thanks for your help !