Intermittent thrust loss (motor stops midflight)


My Hexacopter (Matek F405 miniTE, arducopter 4.3.7, dual Mamba 4-in-1 ESCs running DJI Phantom 2312 motors) developed an intermittent thrust loss issue:

Takes off fine. After couple of minutes of flying, forward-right motor STOPS. Being hexacopter, it stays in the air on 5 motors, controllable, so I can get it to land gently.
After landing and disarming, if I re-arm, all six motors will start, i can take off and fly again until the same motor stops again.

Replaced ESC.
Replaced motor.
Checked/resoldered all wiring to that motor.

What else can it be ?

How can we guess that without a .bin log file?

sorry, that 3.6MB zip file of the log is apparently too big !
Lets try this log_0_UnknownDate

Forgot to mention, when landed with a failed motor, it was bleeping “ESC calibration” tune.

another flight. Same story, motor stops even sooner now. Bleeps like “ESC calibration”. Bit of madness as LOITER tried to stabilize it before landing (thanks for soft grass).

Is this forum broken ? I can’t upload 1.7MB zip file of log, comes with an error “bigger than 4.4MB” ??? ridiculous…

For .bin log files you must use an external file hosting service and post a link here. All forum users do it that way. Just read any other post with a .bin log file.

I think you have the voltage failsafe levels set incorrectly, battery voltage goes very low and the ESCs own low voltage cut-offs are interfering.
You need to use these EXACTLY


and you can disable or lower the ESCs voltage cut-out.

If that bad behaviour continues I think you should have a close examination of the ground wires and signal wires between the ESCs and flight controller.
I am wondering why you dont use DSHOT with a few simple parameter changes.


and set up a serial port with the BLHELI telemetry data

And there is the bi-directional DSHOT firmware.
and you would also need to set

With either of those you can “set and forget” the harmonic notch filter in one step:

INS_HNTCH_ENABLE,1  // write then refresh params to see the rest

Thank you for suggestions.

For BLHELI telemetry: which serial I meant to use ? this frame has a wifi telemetry board, but I don’t use it in flight because of the poor range - do I set that serial port ? I read the telemetry data on FPV OSD.

I thought may have found a suspect: the control wire in the ribbon cable between FC and ESC that corresponds the stopping motor, i found to be worn to just couple of strands. Fixed the wire. One flight was ok, second flight - same problem, same motor shut down.
Drives me mad.

a dud FC ???

(also, this forum IS broken, since I can’t upload a LOG file (not BIN) 1.4 mb size).
here is the external link to 600k BIN file log_3_UnknownDate

Good work in getting the DSHOT going
RCOut: DS600:1-8 PWM:9-12
The BLHELI telemetry wire is just about ESC data that gets logged, and the RPM data can feed into the Harmonic Notch Filter. The logged data alone is very useful in cases like this.

Motor6 (RCout5) is hardly doing anything, is that the motor that seems to cut out?
Is the copter well balanced?
You could try moving the motor wires and motor signal wire to a spare ESC.

The forum is not broken. You are simply not allowed to post big files.
You must use an external hosting website to host them and post a link here like everyone else.

I imagine so, when I cuts out, it reports “Potential Thrust Loss (5)”, though physically it is on servo2 output of the FC, and in the “motor test” page of QGC/MP it’s “Motor A” :slight_smile:

First thing I did when the problem appeared - assumed the 4-in-1 ESC failed on that channel, and moved to another. Then replaced both ESCs with brand new. Then replaced the motor.

Though yesterday I pulled the whole thing apart again, and replaced the 8wire ribbon between FC and ESC.
So far had 5 test flights without any more shutdowns… maybe that was the problem.

Yeah those little cables are pretty cheap (wires and connector housings) and they are not a high-reliability connector. It would be nice if we could get the 4in1 ESCs with JST-GH or click-mate connectors.

Speaking of connectors, what’s the most reliable version of a battery connector ?
I had a treacherous XT60 disconnecting in flight, so I tape or ziptie them up now, but it’s annoying to do every time :slight_smile:

The XT connectors are fine but you have to periodically check and tighten or spread the (male) pins. The 30, 60 or 90 designation represents the peak current capability, not continuous current.

so simple :wink: thanks, I didn’t even think of that