Bad motor? Can you identify the problem? (Photo)

photojunky

photojunky

Well-Known Member
These are photos of the motor that was failing. When I run it, it tries to rotate but only moves in quarter inch increments for a couple of moments. Can anybody identify the issues from this photo? Looks like some stray windings but they did not appear to be hitting anything. Would they cause a short? Not sure about the other side. Could it be arcing? 20180428_190421-1-1.jpg 20180428_190421-1.jpg 20180428_190329-1.jpg
 
Gyro Doctor

Gyro Doctor

Electronics Tech for over 45 years
:eek: ... That's what is generally called one fried motor ... lol ... technically, it lost a phase.
Quad motors are three phased outrunners. Each phase has coils at 180 degrees opposite each other
which, when energised, make the north and south poles of an electromagnet. The carnage you see is one phase
that fried, hence baking the coils in diametric opposition. The general darkening of the coils indicates it overheated
the insulative coating, after which point that fails and arcing occurs which pretty much just trashes the copper wire,
which are the areas that look melted. :) The ESC associated with that motor should also be considered suspect too.
If not for causing the failure then likely it became stressed it's self due to the failure. ;)
 
Last edited:
Rick M

Rick M

Absent-minded professor
Gyro Doctor said:
:eek: ... That's what is generally called one fried motor ... lol ... technically, it lost a phase.
Quad motors are three phased outrunners. Each phase has coils at 180 degrees opposite each other
which, when energised, make the north and south poles of an electromagnet. The carnage you see is one phase
that fried, hence baking the coils in diametric opposition. The general darkening of the coils indicates it overheated
the insulative coating, after which point that fails and arcing occurs which pretty much just trashes the copper wire,
which are the areas that look melted. :) The ESC associated with that motor should also be considered suspect too.
If not for causing the failure then likely it became stressed it's self due to the failure. ;)
Click to expand...

It's good to have an expert or two in the mix.
 
mozquito1

mozquito1

Well-Known Member
The wires are coated in a non conductive coating. Hence the reason they run in water. If that coating has gone then yep it will arc & be erratic. Unless you got the right wire & can wind a motor, you need a new one. Keep the bell & clips as spares.
 
BL Swagger

BL Swagger

Well-Known Member
On the topic of motors... I clipped a branch the other day and the motor top/cap with the propeller popped off. I continued to just put it in back in and the magnetic force was pretty strong pulling it back to place. It seemed to go back normal, and fly fine. This is a first for me, so is the motor ok? Should I replace or just keep going?
 
Jackson

Jackson

USA member at large
BL Swagger said:
It seemed to go back normal, and fly fine. This is a first for me, so is the motor ok? Should I replace or just keep going?
Click to expand...
Sounds like you threw a c-clip, it's on the bottom and fits into a slot of the shaft. Although some newer designs use a shaft screw.

motor_parts_dsc00718.jpg


Newly-Dragonfly-MC2206-2800KV-Brushless-Motor-for-FPV-_1.jpg
 
BL Swagger

BL Swagger

Well-Known Member
Jackson said:
Sounds like you threw a c-clip, it's on the bottom and fits into a slot of the shaft. Although some newer designs use a shaft screw.
Click to expand...

Yes, the same thing happened again, just now, when going around the same tree haha. On closer inspection, I could see the c-clip holding it in was missing. Flies just fine without the clip, but definitely a vulnerability.
 
photojunky

photojunky

Well-Known Member
BL Swagger said:
Yes, the same thing happened again, just now, when going around the same tree haha. On closer inspection, I could see the c-clip holding it in was missing. Flies just fine without the clip, but definitely a vulnerability.
Click to expand...
Do not fly without the clip. It will only end in disaster but I'm sure you know that. The only thing holding it in place is the magnetic force.
 
GJH105775

GJH105775

Off and on
Moderator
photojunky said:
These are photos of the motor that was failing. When I run it, it tries to rotate but only moves in quarter inch increments for a couple of moments. Can anybody identify the issues from this photo? Looks like some stray windings but they did not appear to be hitting anything. Would they cause a short? Not sure about the other side. Could it be arcing? View attachment 4107 View attachment 4108 View attachment 4109
Click to expand...

Are there any marks caused by a screw indenting the coil? Could have shorted through the bell across to the other coil on that same phase.

BL Swagger said:
On the topic of motors... I clipped a branch the other day and the motor top/cap with the propeller popped off. I continued to just put it in back in and the magnetic force was pretty strong pulling it back to place. It seemed to go back normal, and fly fine. This is a first for me, so is the motor ok? Should I replace or just keep going?
Click to expand...


While the magnetic force is usually enough to hold it in place if you were to punch out and then cut throttle the magnetic force would not be too strong, while the prop pulls on the motor with about the same force. This causes a cool looking take away prop, and a not so fun crash. Usually, the quadcopter hits the ground before the prop which looks pretty interesting.
 
Dugdog47

Dugdog47

Well-Known Member
Okay since I've had to learn about these motors lately, what's the popular opinion about the "c clip" versus "set screw" retention on the brushless motors. I E, which is better?
 
Rick M

Rick M

Absent-minded professor
Dugdog47 said:
Okay since I've had to learn about these motors lately, what's the popular opinion about the "c clip" versus "set screw" retention on the brushless motors. I E, which is better?
Click to expand...

I've no experience with the set screw types, but given my experience with c clips, ANYTHING would have to be better. They work great, until they don't...then they come off.

ETA: I'm assuming you would want a tiny drip on blue Loc-Tite on the set screw.
 
mozquito1

mozquito1

Well-Known Member
Screw, but still loctite them. I've bent loads of them clips or lost em when they ping off. Before today I have solderd where the clip should be.
It could have been a small stone done the damage, then broke up & spatt out.
I think if it was a screw, the damage would be full circle on the windings.
 
mozquito1

mozquito1

Well-Known Member
20180428_190329-1-800x617.jpg
WTF is going on under there, someone left an extension lead in it. That looks like the work of a screw but the top one doesn't. That's a big arsed motor.
 
Last edited:
mozquito1

mozquito1

Well-Known Member
Looks like a stone on top but all that loose wire underneath maybe a screw.
If it was a screw on top, there's would be marks the whole way round.
 
You must log in or register to reply here.
Top