-Starting Motor Failure- Error. It is intermittent. Do I need to worry?

[Don Testme]

I crash landed my MAVIC 3 recently. It's been a week since the crash. The drone hit the ground hard and one prop was ripped off. Only cosmetic damage occurred. No repairs were needed.

Since the crash, the left rear motor occasionally won't spin up fully with the other motors , then the drone stops, and I get the "Starting motor failure" error. The motor spins a little , but not as fast as the others. The drone becomes aware of it, then stops the motor start sequence. When I try again, it starts.

After this happens, a second attempt to start the motors always works. The motor in question spins up normally. The drone takes off and flies normally. The motor functions fully without any issue after it starts. It just occasionally doesn't start. Just so you know, for every ten starting attempts, the motor will fail to start once.

My questions are these.

1) WILL THIS PROBLEM BECOME WORSE OVER TIME OR MORE FREQUENT?
2) MY BIGGEST CONCERN- WILL THE MOTOR FAIL, ONCE IT'S STARTED, DURING FLIGHT?
3) DOES IT NEED REPAIR? IF SO, How much do you think it might cost?

Thanks.
Any input will be greatly appreciated.

 

[GFields]

1) WILL THIS PROBLEM BECOME WORSE OVER TIME OR MORE FREQUENT? - Possibly
2) MY BIGGEST CONCERN- WILL THE MOTOR FAIL, ONCE IT'S STARTED, DURING FLIGHT? - another likelyhood. A chance I wouldn't take
3) DOES IT NEED REPAIR? IF SO, How much do you think it might cost? I would have it looked at/reparied.

Do you have DJI Care Refresh?

 

[Don Testme]

Do you have DJI Care Refresh?

I used it up. It's no longer covered. From what I have read on the internet. The motor may need to be replaced.

 

[Don Testme]

I'm fine with the occasional error. The motor functions fine and without issue after the second startup, and doen't happen on every startup.

If, once started, I don't have to worry about the motor suddenly stopping during flight, I will just keep flying as is. But if someone can tell me for sure, there might be a failure during flight, I will send it in for repair.

 

[GFields]

I used it up. It's no longer covered. From what I have read on the internet. The motor may need to be replaced.

Personally, I wouldn't risk it.

 

[GFields]

But if someone can tell me for sure

No one can answer that. But you know it is having an issue and you risk crashing it. A couple of hundred dollars in repair vs losing the drone. A no-brainer for me. Good luck

 

[Phantomrain.org]

I had this very same thing happen where I thought I was ok after a crash.
This video explains why I crashed and what you might look for on your drone that your not seeing.

Phantomrain.org
Gear to fly in the Rain. Land on the Water

 

[Don Testme]

No one can answer that. But you know it is having an issue and you risk crashing it. A couple of hundred dollars in repair vs losing the drone. A no-brainer for me. Good luck

I agree with you both. With my lack of knowledge regarding this issue, repair before flying again is what I should do. While I lack the knowledge, I won't fly it. I have a backup mavic 3. I will use it for now,

My big question is this. Will the motor continue running once it starts and is spinning.

Why do I ask? Most motors and even small ones have "starters".

What is a starter? It's usually a capacitor of some sort or a mechanism that boosts INITIAL power to the motor to get it to spin up. Once this happens, the "starter" is no longer needed to keep the motor spinning.

So, in the case of my drone. Once the motor is started will it stop? I lean toward, it won't stop. So, if the motor does start and once started won't stop, I would hate to spend a hundred or 2 hundred dollars to fix something that doesn't need fixing.

As long as it won't stop once it starts i'm fine. Is anyone privy to this type of knowledge?

 

[rwilliam99]

I agree with you both. With my lack of knowledge regarding this issue, repair before flying again is what I should do. While I lack the knowledge, I won't fly it. I have a backup mavic 3. I will use it for now,

My big question is this. Will the motor continue running once it starts and is spinning.

Why do I ask? Most motors and even small ones have "starters".

What is a starter? It's usually a capacitor of some sort or a mechanism that boosts INITIAL power to the motor to get it to spin up. Once this happens, the "starter" is no longer needed to keep the motor spinning.

So, in the case of my drone. Once the motor is started will it stop? I lean toward, it won't stop. So, if the motor does start and once started won't stop, I would hate to spend a hundred or 2 hundred dollars to fix something that doesn't need fixing.

As long as it won't stop once it starts i'm fine. Is anyone privy to this type of knowledge?

As was stated earlier, no one can really know for sure. It MIGHT be fine, or it might not. Even doing a visual inspection might not catch it. The fact that you are seeing intermittent issues is enough to question the health of it. Given all 4 motors are CRITICAL to keeping the drone in the air, I would not risk it and get it fixed.

 

[Don Testme]

I had this very same thing happen where I thought I was ok after a crash.
This video explains why I crashed and what you might look for on your drone that your not seeing.

Phantomrain.org
Gear to fly in the Rain. Land on the Water

I've had that happen to me a couple times in the past myself. Those prop pieces can snap off if the blades hit something. You won't know it until the plastic piece drops into the motor and either stops it in flight, as it did in your case, or keeps a motor from starting up. This was the case with my past drones, the motor wouldn't start. I was lucky, i didn't crash like in your video.

BUT NOW, I have a different problem. All my props have been replaced and the old ones were inspected (no broken pieces). I Blew each motor with compressed air and inspected for any lodged debri. Nothing was found to cause a PHYSICAL issue.

So I think I have a starter issue. I think. Manually spinning the motor shows no sign of sticking or resistance. Inspection showed no debris or deformity.

I GUESS I'LL JUST SEND IT IN FOR REPAIR. I own 2 mavic 3's. (Long Story). I'll use the other one for now.

 

[Don Testme]

As was stated earlier, no one can really know for sure. It MIGHT be fine, or it might not. Even doing a visual inspection might not catch it. The fact that you are seeing intermittent issues is enough to question the health of it. Given all 4 motors are CRITICAL to keeping the drone in the air, I would not risk it and get it fixed.

OK ! I won't risk it. Getting a repair ticket now.

But still, I'm curious- DOES ANYONE KNOW ABOUT DRONE MOTOR STARTERS AND CAPACITORS? It's interesting. My research suggests the motor may have some type of damage that is causing an imperceptible resistance increase causing the "starter" mechanism to fail.

Luckily I have a backup Mavic three. It even has care refresh.

 

[GFields]

OK ! I won't risk it. Getting a repair ticket now.

But still, I'm curious- DOES ANYONE KNOW ABOUT DRONE MOTOR STARTERS AND CAPACITORS? It's interesting. My research suggests the motor may have some type of damage that is causing an imperceptible resistance increase causing the "starter" mechanism to fail.

Luckily I have a backup Mavic three. It even has care refresh.

Your Mavic 3 does not use capacitors to start the motors. Instead, electromagnetism. When the motor windings become energized (the motors have coils), a temporary magnetic field is created that repels (and/or attracts) against the permanent magnets present inside the motor. This magnetic force is creating the repulsive force in the coil that is used to spin/rotate the shaft. Read more here

 

[rwilliam99]

OK ! I won't risk it. Getting a repair ticket now.

But still, I'm curious- DOES ANYONE KNOW ABOUT DRONE MOTOR STARTERS AND CAPACITORS? It's interesting. My research suggests the motor may have some type of damage that is causing an imperceptible resistance increase causing the "starter" mechanism to fail.

Luckily I have a backup Mavic three. It even has care refresh.

I think that is a reasonable theory, but I have no idea how you would test it out to confirm. At the end of the day, I don't think it really matters - I'm sure the fix for that is to just replace the motor.

 

[old man mavic]

Any damage done to the motor during the crash could have caused several things to take place, it could have very slightly bent the motor shaft ,or caused one of the bearings to move slightly caused ,one of the magnets to become misaligned and so on and so on these things are very difficult to see but when the ESC tries to start the motor, it detects the issue ,and then gives the message you are getting ,the damage could also depend on the temperature of the motor at the time of the start in other words as others have said the only real way to resolve the issue is to have the damage diagnosed and a repair done

 

[rwilliam99]

Any damage done to the motor during the crash could have caused several things to take place, it could have very slightly bent the motor shaft ,or caused one of the bearings to move slightly caused ,one of the magnets to become misaligned and so on and so on these things are very difficult to see but when the ESC tries to start the motor, it detects the issue ,and then gives the message you are getting ,the damage could also depend on the temperature of the motor at the time of the start in other words as others have said the only real way to resolve the issue is to have the damage diagnosed and a repair done

I've been surprised at how sensitive the ESC is - the other day I got an error when trying to take off - one set of props was slightly overlapping and it wouldn't spin them up - it sensed too much resistance. Easy fix, but it amazes me how sensitive these drones are. I doubt it would take a whole lot to get some sort of intermittent failure like what the OP is reporting.