Why did my copter land early? (log attached) (SOLVED)

Hey all,
Curious if someone can investigate this log a little bit? I am just wondering what made my copter land on Friday when I flew it.

I was near the end of a duration / hover test, and my quad landed like it utilized the battery fail safe, but upon checking the log, I can see there is no note of fail safe, nor did it reach the failsafe critical voltage. I had the failsafe critical set to 10.5 volts since its a L-Ion batt.

I am using a 2.1 ProfiCNC cube with a 4 in 1 ESC (35A BLHeli_S) with a Titan Lithium-Ion 14.8v 7.0AH battery and a 3DR power module for voltage and current monitoring, and 780kv t-Motor navigator series motors.

I think it is worth noting as well that I tried to fly the copter afterwards and one of my motors began hanging up as if it had a bad solder joint or a partially disconnected bullet connector. I did a continuity test on the motor (the C motor, i believe… Left rear if you are looking at the top of the copter) and continuity was good, but the motor is still misbehaving. the rest of the motors spin fine but this one hangs up and then causes the ESC or something to beep and it disarms the quad altogether. I am wondering if I got a bad motor from the manufacturer as these are brand new.

attached is the log, if someone more knowledgeable than I can check it out and give me some feedback, I would appreciate it!

This is a Copter-specific question. You may get a better response by moving it to the ArduCopter sub-forum. (Right now, you are in “Hardware”)

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I agree with your observation.
Motor 2 has gone bad in flight as can be seen from the RCout.

So the copter would have been fighting stability while your battery voltage was steadily decreasing.
You were down to 3.25v/cell while it was fighting with that sick motor, steadily reducing the opposite motors.
Pity you were not logging Amps.

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thanks for that! I cant figure out why it isnt recording amperage draw, I have the Power module setup to record both voltage and current… but it’s only recording volts

Update to this,
replaced the motor and it flies very well again
we put the bad motor on the bench tester and it could barely squeak out 340g of thrust at full tilt… we took a good motor off the quad and it made 340g at around 65% throttle. so definitely a motor issue!