Copter descends in Autotune Mode with Copter 3.6.12 firmware

Hello everyone,

Today I started tuning my newly built quadcopter with Copter 3.6.12 firmware, the copter performed normally during Autotune session for 5mins, but then suddenly descended to the ground!!!
I checked the log file but I haven’t found any certain reason for this strange behavior (at the end of the log file).

Link for log file:

Could someone help me have a look at the log file and give me some suggestions? I’ll very much appreciate it. Thanks!

Just before you switched to Loiter after AutoTune it seems you had thrust loss on Motor 4 as it was commanded to maximum. Check the ESC, Motor and prop. Usually when this happens the motor in the opposite leg will drop to minimum to attempt stability but oddly that didn’t really happen. Describe this craft.

Hi I saw the problem in RCOUT of motor 4 as you told me. I will check for the hardware. Thank you!

BlHeli_32 ESC ? They have a feature called thermal throttling…

Hi @dkemxr and @ThePara,
I used KISS ESC 25A 4in1. Do you have an issue when connecting ESC to AUX Port of Pixhawk Cube, the Cube won’t boot completely (orange light blinking continuously). I tried with 2 ESC units but it has the same problem.

You have no choice but to use the Aux ports with Cube Black and Dshot, this is generally not a problem. Why don’t you connect ESC telemetry, it may offer some useful data for troubleshooting.

Hi, in the log file, I connected ESC telemetry also so you can see the motors information. What I can see from motors information is that the current is inside the limit of ESC (25A) but the temperature reached 100degree! I’m not sure why the temperature so high. Another problem is that when connect Cube Black to DSHOT of ESC, the Cube doesn’t boot completely sometimes and orange light keep blinking. Do you know why orange light of Cube keep blinking forever?

If that temperature is right then @ThePara is probably right about throttling. Did you follow the basic tuning guideline in the Wiki before running AutoTune?

I suspect not as the parameters seem to be at default. This could be causing the ESC’s to overheat while running AutoTune which can be very aggressive. Again, describe your craft and it’s components.

What messages does Mission planner give while the LED’s are blinking orange.

Thanks for your help. It is a quadcopter with KISS ESC 25A 4in1, with KDEMotor 965Kv, 4s battery. When I power via USB the Cube boots normally, but when I power via a battery, the Cube keeps blinking orange LED if I connect AUX port to ESC. How can read the message when I power from battery?

If you don’t have telemetry simply connect the USB cable and view the messages in Mission Planner.

I admit I have zero knowledge in the KISS range, but is their telemetry supported by Arducopter in the first place !?

ESC telemetry is in the log.

Hi, while the LED are blinking orange I connect the USB cable and it is a different COM port (COM8) rather than COM9 when it boots normally. I think it is stuck in bootloader mode, but how can I see the console/log of the bootloader to find the issue?

take a look at your battery capacity settings in MP… the quad will land if it thinks it’s near having used up the set capacity of the battery or the limits of the capacity you set as a reserve. BTDT