What can the service life of motors be? I've had 142 hours of flight time and I can hear the whirr of the bearings.

There is nothing to wear out or fail in the motors, they are so simple in construction. The only possible failure point is the ball bearing on the shaft, it may benefit from the occassional drop of oil. But it is near impossible to access the bearing to replace or lubricate it.

118 hours on Mini 2, good as new. 121 hours Mavic 2 pro again sounds, looks, flies good as new.

Hello there. Good day and thank you for reaching out. In addition to this post I will post a link where in you can see some DJI guides on drone maintenance checklist ( https://store.dji.com/guides/properly-maintain-drone/ ) that can help you as well. Thank you and fly safe always.

Be careful with lubricants - unless you know exactly the type to use (if any), you are more likely to cause problems than solve them by adding oil to the prop motors.

Bearings are the only thing that is "sealed". adding oil will just attract dust/dirt ion take off/landing.
The motor itself is easily blown out with some of the "canned air/duster" sold at electronic shops.
That's it to the motors.
What you are hearing/feeling is the "cogging" of a brushless motor.

A couple of hundred hours is nothing.
Brushless motors have a service life of tens of thousands of hours.

Problem fixed. Vibrations from the engine transferred to the arm and there was a nagging resonance. Tightening the screws from the bottom helped.

Do the rear engines have a different design, and maybe more power than the front engines? You can feel clearly greater resistance resulting from overcoming the magnetic flux.

djiuser_nO2RdSW5BSUg Posted at 3-10 00:19
Do the rear engines have a different design, and maybe more power than the front engines? You can feel clearly greater resistance resulting from overcoming the magnetic flux.

All four motors are identical, except that two spin clockwise and two are counter-clockwise,
The speed they run at varies according to the way the flight controller directs to make the drone do what you want it to.
In normal flight the rear motors would be spinning a little faster to tilt the front down.

However, the conducted experiment shows something else. The force needed to overcome the magnetic flux resistance of the rear motors is slightly higher. I recommend that you do your own experiment. Visually, the engines are very similar.

djiuser_nO2RdSW5BSUg Posted at 3-10 03:17
However, the conducted experiment shows something else. The force needed to overcome the magnetic flux resistance of the rear motors is slightly higher. I recommend that you do your own experiment. Visually, the engines are very similar.

They are identical.
How fast they spin varies with the power sent to them by their ESC.

djiuser_nO2RdSW5BSUg, YOU hit upon it, once about every 10 to 15 flights, I test each screw with a screwdriver,
very seldom do I find one that loosened very slightly.  But a good idea now and then.

Labroides Posted at 3-10 06:00
How fast they spin varies with the power sent to them by their ESC.

Would you mind reading a post before replying?
User_xxxxx explained twice he refers to the different resistance he feels when turning the props by hand. This has nothing to do with your answers.
Thank you.

Landey Posted at 3-12 22:05
Would you mind reading a post before replying?
User_xxxxx explained twice he refers to the different resistance he feels when turning the props by hand. This has nothing to do with your answers.
Thank you.

I did read the post and answered appropriately.
If his drone is flying normally, there is nothing at all wrong with the motors.
It's very common for people to imagine all kinds of non-existent faults.

Labroides Posted at 3-12 22:16
I did read the post and answered appropriately.
If his drone is flying normally, there is nothing at all wrong with the motors.
It's very common for people to imagine all kinds of non-existent faults.

Sorry, man ... I politely asked you to read posts before replying. I regard this as a simple matter of courtesy.
You still did not read.
Please do so.

--- Back to topic ---

djiuser_NOxxxxx: You're right! There's a noticeable difference of the resistance caused by the motor magnets between front and rear motors. So they obviously aren't identical.
Would be interesting to know a bit more about that.

Landey Posted at 3-13 00:43
Sorry, man ... I politely asked you to read posts before replying. I regard this as a simple matter of courtesy.
You still did not read.
Please do so.

Don't be ridiculous telling me that I didn't read something, and then telling me again.
I read your reply to.
And you have no idea what you are talking about, whether it's about drones or about giving people a lesson in "courtesy".

Labroides Posted at 3-13 02:34
Don't be ridiculous telling me that I didn't read something, and then telling me again.
I read your reply to.
And you have no idea what you are talking about, whether it's about drones or about giving people a lesson in "courtesy".

I don't like repeating myself over and over, I also don't wish to flood a thread with useless replies.
So I'll try to make this a useful reply and settle the matter.

I was wrong with one point: I shouldn't have written "Read", I should have written "Read and understand".
If you read and understood djiuser_NOxxxxxs post and my reply to him, you should have understood what we are talking about. It's not about any issues, defects and the like. It's about the fact that front and rear motors behave differently when turning them by hand. Try this. You will notice that the rear motors feel totally different compared with the front motors. That's what djiuser_NOxxxx meant using terms like "magnetic flux". I deliberately used other, more simple terms so you could also get an idea of the topic, which unfortunately did not happen.

Then you tell me that I have no idea what I am talking about drones.
So please show me how you came to this conclusion, show me where I said anything wrong about drones. Will close the loop to the initial 'Read before you write' bone of contention.


But I friendly invite you to join the talk about the different motor "feel", maybe you can share some enlightening ideas.

djiuser_nO2RdSW5BSUg Posted at 3-10 00:19
Do the rear engines have a different design, and maybe more power than the front engines? You can feel clearly greater resistance resulting from overcoming the magnetic flux.

The Flight controller is the computer at the heart of everything the drone is doing. It receives data from every source including RC, GPS, IMU, ESCs sensors/cameras PMU/VPS etc.
The flight controller will receive data inputs, interpret the best way to achieve what is being demanded and then command the motors react in a way that will achieve the outcome you’re looking for.
Drones usually have the ability to go the same speed forward backwards and sidewards so you would imagine that motors are pretty much identical. Its a very rare thing to hear of a worn out motor.

Incidentally bigger newer more expensive drones can have multiple flight controllers to allow for failure redundancy.

Checking your drone inflight at low altitude in open space is usually a good indicator if its flying well or you have a problem

Landey Posted at 3-13 03:32
I don't like repeating myself over and over, I also don't wish to flood a thread with useless replies.
So I'll try to make this a useful reply and settle the matter.

Read my earlier posts and I explained it there.
Now don't bother me again.
I've already wasted more time than I want to on your stupid posts.

hallmark007 Posted at 3-13 03:35
The Flight controller is the computer at the heart of everything the drone is doing. It receives data from every source including RC, GPS, IMU, ESCs sensors/cameras PMU/VPS etc.
The flight controller will receive data inputs, interpret the best way to achieve what is being demanded and then command the motors react in a way that will achieve the outcome you’re looking for.
Drones usually have the ability to go the same speed forward backwards and sidewards so you would imagine that motors are pretty much identical. Its a very rare thing to hear of a worn out motor.

Just try to turn the front and rear motors slowly with your fingers.
With my Mini 2, there's a totally different feel between front and rear motors - same as with djiuser_NOxxxx.
It feels like the rear motors have stronger magnets, the propellers tend to 'lock' with slightly more force. It's not wrong, it's just different.

Maybe this is just a random coincidence, so give it a try and share the results.

Landey Posted at 3-13 03:44
Just try to turn the front and rear motors slowly with your fingers.
With my Mini 2, there's a totally different feel between front and rear motors - same as with djiuser_NOxxxx.
It feels like the rear motors have stronger magnets, the propellers tend to 'lock' with slightly more force. It's not wrong, it's just different.

Most Drones today are powered by brushless Electric motors and are of the our runner type. This means the whole outer body of the motor spins to turn the prop as opposed to an in runner motor where the central shaft will rotate the prop . Out runner motors produce more torque which is needed for large medium props.

The components of a DC motor are a rotor and permanent magnets and the stators . Electric current flows through two wires at the time creating an alternative electromagnetic field around the permanent magnets pushing and pulling them to create the spinning action.

Electric motors are rated by their rotations per volt Kv value. Higher Kv values 1000kv plus are better for agility and acceleration they’re less stable and carry lighter loads.
Smaller props like on mini should be placed on high Kv motors . Low Kv 800 or less have more torque can carry heavier payloads and fly faster.

You can test your motors before flight. Manually twist them to ensure you feel no grating in the motor interior . Grating “will” indicate the motor interior is compromised and you need to replace. You can check this on the ground and the only other check you can realistically make is the temperature of each motor post flight, if one is excessively hot then I’d say that’s a problem.

If they are moving smoothly and are not excessively hot post flight they’re fine. And its very rare to find bad ones.on these drones anyway.

Landey Posted at 3-13 03:44
Just try to turn the front and rear motors slowly with your fingers.
With my Mini 2, there's a totally different feel between front and rear motors - same as with djiuser_NOxxxx.
It feels like the rear motors have stronger magnets, the propellers tend to 'lock' with slightly more force. It's not wrong, it's just different.

I have sent my Mini2 to my grandson in Sweden, so cannot check, but I have a few drones here and checking them on the ground not started they all seem to have slight discrepancies, but if you can imagine them being commanded to spin at certain rates you’ll find that the slight discrepancy in motors as you manually spin them will not show any resistance. But yes they don’t feel exactly the same when manually turning them. But just keep in mind if its smooth its good grating then not good.

Landey Posted at 3-13 03:44
Just try to turn the front and rear motors slowly with your fingers.
With my Mini 2, there's a totally different feel between front and rear motors - same as with djiuser_NOxxxx.
It feels like the rear motors have stronger magnets, the propellers tend to 'lock' with slightly more force. It's not wrong, it's just different.

Without going into polemics with people whose knowledge is not supported by extensive experience, I can say that in the macro photo I noticed a slight difference in the size of the gaps between the magnet and the motor coil pole. The differences are in the front and rear engine. I will try to measure this gap and compare the two engines with each other.

hallmark007 Posted at 3-13 07:13
I have sent my Mini2 to my grandson in Sweden, so cannot check, but I have a few drones here and checking them on the ground not started they all seem to have slight discrepancies, but if you can imagine them being commanded to spin at certain rates you’ll find that the slight discrepancy in motors as you manually spin them will not show any resistance. But yes they don’t feel exactly the same when manually turning them. But just keep in mind if its smooth its good grating then not good.

Morning, hallmark007! ;)

I know a bit of motors, I do sim racing with a capable gear. But your explanations are good to know for everyone.

Don't get me wrong: I do not suspect any motor damages or malfunctions, my Mini 2 just behaves wonderful (except the camera) and exactly as it should, it's a very nice little thing.
I read djiuser_NOxxxxs post about the different feel of front and rear motors, so I tried myself.
And indeed, there's a noticeable difference between front and rear motors; it's a pity you don't have a Mini 2 to try yourself. I'll try to describe the effect as good as possible:
If you turn the front motors slowly with your fingers, you of course feel a light resistance (like a tiny bump) caused by the magnets and coils, turning resistance slightly changes while turning, a bit more, a bit less, which is perfectly normal. In fact, this is a highly discussed topic among sim racers, because sim racers want a very smooth experience without feeling any "bumps" when turning the wheel. This is according to the motor type (stepper or servo motors) and the control software.
Now we've got a light "bump" feeling with the front motors; but if you slowly turn the rear motors by hand, this "bump" feeling is stronger, it's almost like the rotor has a stronger magnetic resistance to overcome, it almost clicks into place between the positions defined by the coils.
That's what djiuser_NOxxxx noticed, and I notice the same.
Light magnetic resistance at the front, stronger resistance with the rear motors.
This could be pure random coincidence due to manufacturing deviations, but also an indication of DJI using different motors for front and rear.

As said: There's nothing wrong, it's just interesting to know.

Landey Posted at 3-13 22:58
Morning, hallmark007! ;)

I know a bit of motors, I do sim racing with a capable gear. But your explanations are good to know for everyone.

And indeed, there's a noticeable difference between front and rear motors; it's a pity you don't have a Mini 2 to try yourself. I'll try to describe the effect as good as possible:
There have been similar posts for years.
There are always users imagining that there's something wrong with their motors.

Light magnetic resistance at the front, stronger resistance with the rear motors.
This could be pure random coincidence due to manufacturing deviations, but also an indication of DJI using different motors for front and rear.
The motors are identical, despite your insistence that they aren't.
There is no front or back to your drone.
It goes just as well forwards, backwards or sideways, so there would be no point at all in having different motors an one side.
The speeds of the motors are constantly monitored and varied by the flight controller, not by having different spec motors.

If your drone is flying well, your motors are fine and there's no need for the hypochondria.

Labroides Posted at 3-13 23:35
And indeed, there's a noticeable difference between front and rear motors; it's a pity you don't have a Mini 2 to try yourself. I'll try to describe the effect as good as possible:
There have been similar posts for years.
There are always users imagining that there's something wrong with their motors.

Labroides ... Just yesterday and further up this thread I politely asked you to read before you write, several times. How about eventually giving that a try?

Quote: "There are always users imagining that there's something wrong with their motors."
Nobody wrote about anything wrong with their motors. Just read.

Quote: "The motors are identical, despite your insistence that they aren't."
You just quoted me writing "This could be pure random coincidence due to manufacturing deviations,  but also an indication of DJI using different motors for front and rear."
See? I wrote that it could be just manufacturing deviations - so where do you see anyone insisting on the motors being different? We're trying to find out IF the motors are different, we're not insisting them to be. Just read.

Quote: "There is no front or back to your drone."
There's a camera on one end, which I call front. It's not there at the other end, so I am quite sure my drone has a front and a back.

Quote: "It goes just as well forwards, backwards or sideways, so there would be no point at all in having different motors an one side."
You never thought about weight distribution? I just leaned my Mini 2 on the edge of a scale - first with it's front, then with it's back.
Scale showed 105 g for the front, 133 g for the back. So it seems the Mini 2 is heavier at it's back - that's where the battery is. Surprise.
So it needs a bit (~ 30 %) more power to lift it's back. Does that trigger an idea? Maybe an idea about the topic of this discussion?

Quote: "The speeds of the motors are constantly monitored and varied by the flight controller, not by having different spec motors."
No, really??? Of course the motor speeds are monitored and adapted. But this doesn't prevent anyone from using different motors. You might not believe, but even different motors can be monitored and adapted to work in sync.

Quote: "If your drone is flying well, your motors are fine and there's no need for the hypochondria."
Again: Nobody said the motors aren't fine. We are not talking about the motors malfunctioning, we are talking about the motors possibly being different. You would have known that if you read what we wrote.

Closing words: Futher up this thread, you told me: "Now don't bother me again. I've already wasted more time than I want to on your stupid posts."
You asked me not to reply to you again, you stated you regard spending time with my stupid posts as a waste. I respected your wish and did not reply anymore.
Now you actively reply to me and decide to waste even more time on a matter you still didn't understand because you still didn't read?
Oh, come on ... ;)

Landey Posted at 3-13 22:58
Morning, hallmark007! ;)

I know a bit of motors, I do sim racing with a capable gear. But your explanations are good to know for everyone.

Honestly I’ve never noticed and I don’t have anything that noticeable here. Probably a stupid question but is the resistance clockwise and anti clockwise in both sets of motors.

djiuser_nO2RdSW5BSUg Posted at 3-13 22:39
Without going into polemics with people whose knowledge is not supported by extensive experience, I can say that in the macro photo I noticed a slight difference in the size of the gaps between the magnet and the motor coil pole. The differences are in the front and rear engine. I will try to measure this gap and compare the two engines with each other.

Hoi! How about changing your name, making it a bit easier to refer to you?

So this indeed points to slightly different motors for front and rear.
If this turns out to be true, I guess the rear ones are a bit beefier to compensate for the higher weight at the back of the drone.
Thank you very much for digging a bit deeper into this! It doesn't make any practical difference, but I find it quite interesting.

hallmark007 Posted at 3-14 01:29
Honestly I’ve never noticed and I don’t have anything that noticeable here. Probably a stupid question but is the resistance clockwise and anti clockwise in both sets of motors.

I wouldn't have noticed that, too. I just got curious after I saw djiuser_nOxxxx mentioning it. ;)
I tried what you suggested - and I did not feel a difference with clockwise and anti clockwise rotation.
Just the difference between front and rear motors, with the front motors tending to turn a bit "smoother"; the rear ones almost clicking into place.
Maybe it's just slightly different magnets in the rotor.

Landey Posted at 3-14 01:39
I wouldn't have noticed that, too. I just got curious after I saw djiuser_nOxxxx mentioning it. ;)
I tried what you suggested - and I did not feel a difference with clockwise and anti clockwise rotation.
Just the difference between front and rear motors, with the front motors tending to turn a bit "smoother"; the rear ones almost clicking into place.

One thing to bare in mind if you have different motors with different kv then they will all reduce to the power of the weakest one. This would say to me that it would be pointless putting on motors with different kv. Weight most drones are built with as much even distribution as possible, but as you say with mavics in general they are slightly back heavy at least the new ones. So this is easily controlled by sending more power to the rear to command level attitude at hover. I know the theory of motors and when stripping them down they were the same. There is many things changing and improvements being made it hard to always keep up. So I cannot say for certain. Maybe a poll might give you some answers, if they are all the same then there might be something to it and if it varies then it’s likely just a manufacturing anomaly.

Landey Posted at 3-14 01:39
I wouldn't have noticed that, too. I just got curious after I saw djiuser_nOxxxx mentioning it. ;)
I tried what you suggested - and I did not feel a difference with clockwise and anti clockwise rotation.
Just the difference between front and rear motors, with the front motors tending to turn a bit "smoother"; the rear ones almost clicking into place.

One thing to bare in mind if you have different motors with different kv then they will all reduce to the power of the weakest one. This would say to me that it would be pointless putting on motors with different kv. Weight most drones are built with as much even distribution as possible, but as you say with mavics in general they are slightly back heavy at least the new ones. So this is easily controlled by sending more power to the rear to command level attitude at hover. I know the theory of motors and when stripping them down they were the same. There are many things changing and improvements being made it hard to always keep up. So I cannot say for certain. Maybe a poll might give you some answers, if they are all the same then there might be something to it and if it varies then it’s likely just a manufacturing anomaly.

Landey Posted at 3-14 01:39
I wouldn't have noticed that, too. I just got curious after I saw djiuser_nOxxxx mentioning it. ;)
I tried what you suggested - and I did not feel a difference with clockwise and anti clockwise rotation.
Just the difference between front and rear motors, with the front motors tending to turn a bit "smoother"; the rear ones almost clicking into place.

I never pay attention to nicknames and avatars, but especially for you I can be nOxxxx
The magnets look very similar at high optical magnification, but the magnetic gap appears to be different. I also want to measure and compare the outer diameter of the rotor. I also want to show that the increase in resistance is not related to the closed circuit of the transistor, which will definitely increase the mechanical resistance during induction of current in the coil.

Landey Posted at 3-14 01:19
Labroides ... Just yesterday and further up this thread I politely asked you to read before you write, several times. How about eventually giving that a try?

Quote: "There are always users imagining that there's something wrong with their motors."

Just yesterday and further up this thread I politely asked you to read before you write, several times. How about eventually giving that a try?
... you still didn't understand because you still didn't read?

Despite your yapping that you think I didn't read the nonsense you wrote, I read it very well and I understood what I read.
And on top of that (unlike you) I understand how DJI drones work.
If you don't have the intelligence and temperament to gracefully accept advice from others, how about you stop being an annoying little twat.

When I started this thread I had an issue with the noticed noise of the bearings on both rear motors. At one point the noise became a nuisance, it seemed to me that tightening the screws of the engine structure from below brought an improvement, but it was only an illusion. I sent the drone to the service DJI and got the drone in return, possibly a refurbisch. Now there is a big improvement. I have assessed the chances of replacing the bearings myself, but there are some difficulties. The rotor shaft is glued in and the ball bearing is secured with the crimped edge of the housing. There are two bearings, one plain at the bottom and one ball bearing at the top. The bottom is not sealed, but a sponge pad provides some protection. The upper bearing is type ZZ. Most likely in the size of 2x5x2.5 mm. I will want to verify it in order to replace it myself later. And also a curiosity. The refurbished drone had a slightly skewed rotor. Today I also want to measure the curvature with a dial gauge.

Landey Posted at 3-14 01:39
I wouldn't have noticed that, too. I just got curious after I saw djiuser_nOxxxx mentioning it. ;)
I tried what you suggested - and I did not feel a difference with clockwise and anti clockwise rotation.
Just the difference between front and rear motors, with the front motors tending to turn a bit "smoother"; the rear ones almost clicking into place.

Don't worry about what Labroides writes. He's an old, decrepit troll. He always spoils the discussion and gets unhealthy satisfaction from it. My advice is to just spray him with warm urine.

nOxxxx Posted at 3-14 02:49
When I started this thread I had an issue with the noticed noise of the bearings on both rear motors. At one point the noise became a nuisance, it seemed to me that tightening the screws of the engine structure from below brought an improvement, but it was only an illusion. I sent the drone to the service DJI and got the drone in return, possibly a refurbisch. Now there is a big improvement. I have assessed the chances of replacing the bearings myself, but there are some difficulties. The rotor shaft is glued in and the ball bearing is secured with the crimped edge of the housing. There are two bearings, one plain at the bottom and one ball bearing at the top. The bottom is not sealed, but a sponge pad provides some protection. The upper bearing is type ZZ. Most likely in the size of 2x5x2.5 mm. I will want to verify it in order to replace it myself later. And also a curiosity. The refurbished drone had a slightly skewed rotor. Today I also want to measure the curvature with a dial gauge.

Motors are extremely cheap, if you want to change one check eBay a lot easier than stripping one down . The refurbish is as new and many times will be equal and better than the drone its replacing. Its very rare these motors will need replacing. Other option for you if you are interested in stripping your drone is look for a crashed one .

nOxxxx Posted at 3-14 03:00
Don't worry about what Labroides writes. He's an old, decrepit troll. He always spoils the discussion and gets unhealthy satisfaction from it. My advice is to just spray him with warm urine.

Yeah .. a few facts and experience tend to spoil the kind of wankery you are attempting.

I am enclosing a link to the video of my engine before replacement.

https://drive.google.com/file/d/1yJM6HQiolaIwlNRxvh9sFEdRJAbG3Ags/view?usp=drivesdk

hallmark007 Posted at 3-14 03:07
Motors are extremely cheap, if you want to change one check eBay a lot easier than stripping one down . The refurbish is as new and many times will be equal and better than the drone its replacing. Its very rare these motors will need replacing. Other option for you if you are interested in stripping your drone is look for a crashed one .

50 EURO for one arm with a mini 2 engine is too much for me. The revolutions of these engines exceed 20,000 per minute, their service life is about 100 hours of flight in my case, which I made in 10 months during flights over a distance of 3,500 km. These bearings are really cheap and weak. The rear ones will drop faster than the front ones, so I am looking for an answer to why the rear engines have a slightly different design.