Infamous stuck motor issue strikes again

[Chaosrider]

Bear in mind that forums etc. see a skewed sampling, FAR MORE people post problems than "sing praises" in fact people rarely post to sing praise.

I do...

All Minis are good!



TCS

 

[Chaosrider]

The biggest problem I have with option A is that seeing as this stuck motors problem is quite widespread,

Define "widespread".

I have 3 Mini-2s that I've been flying for almost a year, and I've never seen a motor stick. Of course, I fly them all regularly.

What's the incidence of this problem in the Mini-2? 1% of the fleet?

Following up on what the OP said, you read about airline crashes. You don't read about the bazillion flights that are completed without incident.

MM

 

[lensimages]

Hey all,

I am in a bit of a bind here and I would very much appreciate your help.

Just recently I had to take the painful decision to part with expensive bits of kit that see little to no use due to time constraints; unfortunately the Mini 2 is one of them.

Now, I've had the drone a little under a year and in that time it has literally flown 4 times including today. The drone is immaculate, always kept in its bag or on a dust free shelf, never crashed, made sure to hand launch when I was in an environment where dust could be an issue etc etc.

So today I meet a person interestedin buying the Mini and we do a test flight. I put the drone on the pavement, manually start the motors and I notice that the left front props are not spinning and shortly after the others stopped (or could be that I stopped them, can't remember).
I pick up the drone and try to spin the props and I notice that they seemed to be stuck. The props would turn but veeeery reluctantly and the whole rotor seemed to be "dragging" for lack of a better word. The other 3 motors spin very easily and would go from magnet to magnet very crisply/distinctly.
The stuck one felt like it was gummed up.

I looked at the motor and didn't see anything out of the ordinary. After a while, rotating the props the motor seemed to free up and eventually it felt fine. I started the drone, let it hover and then flew a whole battery around with absolutely no issue at all.
However, upon landing the left front motor seemed to be gummed up again.

Obviously i had to put the sale on hold until I address the issue.

I purchased the drone directly from DJI online 345 days ago. I guess I should send the drone back to DJI but I feel reluctant to do so for the following reasons:

1. I am afraid they will replace my new drone with a refurbished one, which I would not want under any circumstances.
2. Would the drone need to be shipped off to China? If so It would be a huge hassle to do so, let alone the costs associated with posting.
3. I think that you now need to send the drone plus the controller back, which would make posting ever more of an issue.
4. I heard that when DJI gets a drone back for repair they update to the latest FW, which I want to avoid as I am on 1.3 and want to stay there.

Also, would I be covered under warranty? How likely would it be to tell me that they will be charging me for the repair?

To cut a long story short; I would prefer to fix ONLY the motor under warranty and locally ideally. Would this be possible or am I looking at opening up a repair case with DJI etc etc?

Had similar problem but only one motor , less than a year old so was still under warranty so sent it back to supplier after contacting them, had a brand new one sent me as a replacement, cheers Len

 

[rcb]

I’ve had some experiences with stuck or sticky motors and it always seems due to some very fine particle contamination. By turning the drone upside down and carefully blowing the motor out while very very gently operating the prop back-and/or-forth as freedom of motion allows, I’ve always been able to to clear it out.

 

[cheddar-man]

So far never had a motor stick (which doesn't help the OP!
If you have proof of purchase then 345 days is still well inside the one year warranty period!
Where are you communicating with?
If you're in the UK/Europe, talk to "[email protected]" I have found them very helpful and quick. Do you have a DJI Account? Your drone should be listed there from when you activated it along with all relevant information.
The bearings in the motors are "shielded" I believe. If the grease is seeping out it would tend to indicate overheating.

 

[c64-dev]

Well, yesterday after cleaning the oily substance from the motor it freed up the rotor movement significantly. It still doesn't step from magnet to magnet so crisply but still you can make out the magnet steps.

After that the drone started up the motors every single time happily. Now it starts, it stops, it flies, all without a hitch. If you didn't rotate the motor by hand you wouldn't know there is a problem; at least fow now.

What do you guys think I should do? Should I return it or simply leave it as is?

 

[c64-dev]

So far never had a motor stick (which doesn't help the OP!
If you have proof of purchase then 345 days is still well inside the one year warranty period!
Where are you communicating with?
If you're in the UK/Europe, talk to "[email protected]" I have found them very helpful and quick. Do you have a DJI Account? Your drone should be listed there from when you activated it along with all relevant information.
The bearings in the motors are "shielded" I believe. If the grease is seeping out it would tend to indicate overheating.

Thanks for the info kind sir.
I haven’t really been in touch with DJI about it yet. I just wonder if it’s an overkill to return an otherwise amazingly great drone for this issue which as you can read above seems to mostly have cleared out.

I do have a DJI account and the drone is listed there indeed. As for overheating, what you mention makes perfect sense. Having said that, I haven’t noticed the motor being any warmer to the touch than the others but I will run again some more tests and see.

 

[cheddar-man]

If you're in UK/Europe it doesn't hurt to let them know of the issue. The fact it's resolved itself would suggest that there may have been a bit of dirt in there which has subsequently come out with the grease. Give them a heads up that there may be a warranty problem in the future.

 

[c64-dev]

I am currently in Greece and will stay here for the time being.
I just went to the main (and only) DJI reseller here in Athens and was a bit underwhelmed by their customer service.

The guy had a halfhearted look at the motor issue, saying simply that I need to change the motor. My goal going there was to get a bit of reassurance that either 5e issue with the motor is not a big thing or if it is get some pointers on how to go about with my expiring warranty and the potential service.

He said that they don’t handle warranty claims and if I want to open a case I would have to do it directly with DJI. He told me that even if the issue is not apparent now it might come back and if it does while in flight.... I absolutely agree with him on that, but his bored attitude kind of put me off.

I guess my main issue is that I paid 600 euro for this brand new drone and even though it now functions fine I am a bit upset about having to deal with a problem on something of such supposed high quality. Also, I am a bit skeptical about what I will receive if I send in my drone; I know refurbs are fine and the point will be moot if I end up selling the Mini but still...

The cost of replacing the arm is 75 euro, motor and all but I was thinking if by trying to use the warranty I could be spared the cost.
Would there be a chance I would be asked to pay for shipping and repair costs if I send it in?

Also, do you guys think that this issue might return while in flight? Could I trust the drone as it is?

 

[Faster]

I wouldn't trust that motor again unless I can test it thoroughly. I would turn on/off and hover near ground at least 20 times for being a little bit more confident. On the other hand you can send it to DJI for replacement/repair before warranty expires. I wouldn't be worried getting a refurbished unit. My Air 2 S is refurbished and flies beautifully.

 

[Deleted member 154384]

wash the engine with electronic cleaner and finally give a drop of oil on the bearings.

 

[cheddar-man]

The bearings are shielded and filled with grease. Not a good idea to start pouring oil in there!!

 

[c64-dev]

I am quite curious to see a complete tear down of a Mini motor. Being an engineer, the whole issue has piqued my curiosity.

 

[cheddar-man]

Fairly simple really. In the case of the Mini 2 the motors comprise 12 stator windings fed by the ESC. There is a spindle mounted on two bearings running through the stator and the rotor is mounted on this. The rotor comprises a ring of 12 powerful magnets that surround the stator and this is what the propellers is mounted on. The attached picture from the web gives you an idea.

 

[Deleted member 154384]

 

[Faster]

The bearings are shielded and filled with grease. Not a good idea to start pouring oil in there!!

Metal or rubber shield? I think they are metal shielded, if so, they are not completely sealed and can be oiled. I'm not saying that you need to do it on our drones, but it can be done.

 

[Deleted member 154384]

Metal or rubber shield? I think they are metal shielded, if so, they are not completely sealed and can be oiled. I'm not saying that you need to do it on our drones, but it can be done.

They have a very normal non-hermetic metal shield.

This is an example of maintenance Cleaning the engine.

As you can see from the photo, our motors dji mini 2 only have a ball bearing, below we find a classic brass bushing.

 

[Faster]

They have a very normal non-hermetic metal shield.

This is an example of maintenance Cleaning the engine.

As you can see from the photo, our motors dji mini 2 only have a ball bearing, below we find a classic brass bushing.

View attachment 147063

Lol, brass bushing on the lower? I've never ran a motor with brass bushings in my whole RC life. Cheapie these people at DJI.

 

[Deleted member 154384]

The photos are not mine, but found on the net ... having never disassembled an engine of my mini 2 now I wonder? how does the bell stay still and not slide upwards if we do not find a ball bearing with a seeger ring underneath?
I'm missing something ..

 

[Faster]

The photos are not mine, but found on the net ... having never disassembled an engine of my mini 2 now I wonder? how does the bell stay still and not slide upwards if we do not find a ball bearing with a seeger ring underneath?
I'm missing something ..

It must have it, some kind of stopping ring on the bell shaft.