Hi all,

I'm experiencing a stiff motor bearing on one of the 4 motors arms on my Mini Pro 3. (less than one year old)
I have read various topics on this already with several possible reasons.
I decided to post mine since I think my case can be a bit different and hope to get some good advice / peace of mind.

2 weeks ago I flew my drone in Iceland in colder conditions as I usually flew in. (mostly flew only this summer so far).

When I prepared for the first flight and started the engine the left back motor didn't start.
The message Motor stock appeared and it didn't fly.
Next day I got it to work again by manually rotating a bit.

Good to know:

- The drone never crashed or got any sand in it. Only thing is that it was in my suitcase while traveling.
- The drone didn't get any maintenance or has damaged / worn out propellers.
- Before it happened, I never manually moved the rotors so I don't know if the rotor was moving stiff from the start
- It's still stiff now but so far the issue didn't happen again when back home. So it only seemed to blocking the rotor when really cold.

My main concern now is:

- Can this happen all the time when I fly in cold conditions?
- Can this lead to additional issues, even in-flight blocking? Or perhaps can the stiffness cause the drone to fly unstable?

Any suggestions on what to do?

Thanks
Onne

Hello, there. Thanks for your feedback. About the drone in cold conditions, users should pay attention to the humidity of the environment when the temperature is really cold.
When the air humidity is relatively high in cold weather, the moisture in the air will continuously adhere to the high-speed rotating propellers, and condense into an ice layer on the leading edge of the propellers. After icing, the aerodynamic shape and inertia of the propellers have changed a lot. In order to ensure stable flights, the motors need to provide more force so that the motors will be overloaded. As the ice layer gets thicker and thicker, when the motor cannot provide enough torque, the aircraft will fall or even make an emergency landing. The motor may be overheated and burned out due to the severe overload. This is also one of the reasons why the aircraft do not support flying in bad weather such as rain, snow, and fog.

According to your description, the issue has not occurred again since last time and seems to only occur in cold weather. If the aircraft works properly and does not have any error message. You can continue using the aircraft. If the issue occurs again, you are advised to send it back for further diagnosis. Here is the link: https://www.dji.com/support/repair?site=brandsite&from=footer

Thank you for the feedback DJI Wanda.
It's good to know and might indeed also be informative to other users.

Regarding my case the issue happened right on my first attempt without having the drone exposed to the cold / humidity for long. There was also no ice / snow involved on the propellers.
So from getting the drone from my car to the flight scene was about 10 minutes in. I put it one flat ground, powered it on and when GPS was located went in flight mode.
Could thise have been enough for the propeller to change to a more tight fit?

My main concern now left is that that particular motor is moving stiff. (but flight seems okay). And of course in the future there might be a situation where I want to fly it in colder weather. (cold as in, freezing)
What I will at least do now based on your feedback, is have a long flight on safe height so see if heating becomes a problem.
I'll report back on this as soon as there are less windy conditions here.

OnneW Posted at 12-11 05:58
Thank you for the feedback DJI Wanda.
It's good to know and might indeed also be informative to other users.

Hi, may we know the temperature range the drone was in at that time? The operation temperature range for DJI Mini 3 Pro is -10° to 40° C (14° to 104° F), if it is below -10° C, we may not be able to assure the performance. Besides, you may check the drone more times and see if the issue will exist again. Thank you.

DJI Susan Posted at 12-11 22:17
Hi, may we know the temperature range the drone was in at that time? The operation temperature range for DJI Mini 3 Pro is -10° to 40° C (14° to 104° F), if it is below -10° C, we may not be able to assure the performance. Besides, you may check the drone more times and see if the issue will exist again. Thank you.

The temperature was about -2 degrees celsius.
Thinking back, I would say there was quite some humidity and wind.

I haven't been able to test flight in the past 2 days because of heavy wind and a lot of rain.
As soon as I can I'll do a long flight to check for any abnormalities.

OnneW Posted at 12-13 00:35
The temperature was about -2 degrees celsius.
Thinking back, I would say there was quite some humidity and wind.

Please keep us updated on your test results.

Hi Wanda and Susan,

I think the drone is fine.
I was able to get steady flights today and the motor stuck didn't happen again.
It might be a placebo effect but I think the bearing is a bit more smooth and similar to the other 3 rotor arm bearings now.
So the flights might have improved that.

Since I focus on every little detail for me to close the topic, I'd like to confirm one more thing with you.
I had to calibrate the IMU and compass since at first it didn't remain still at all in the air.
After having done that (the IMU actually 2 times), it seems to go almost perfectly straight forward and backward (and left and right).
- One question on that, is it normal that a deviation of 5-10 cm going forward and backward happens. It seems to correct itself since sometimes it goes left and sometimes right.
So it doesn't wander completely left or right like it did before the IMU calibration.

- Lastly, is there anything interesting I could check in the data logs about the motor stuck topic?

Thank you

Btw, here's the footage I made in Iceland with it.

https://forum.dji.com/forum.php? ... d=303389#pid3201806