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Warning! Check your motors...

xcrost

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I thought I would share my (new to me) Tello experience. Recently I underwent a complete motor change and changed to new (cheap) propellers. You know, the 5 color ones. 10 bucks for 10 pairs. I have used these before and they were "ok". After many flights of Tello behaving "normally" I inadvertently touched one of the motors post flight and it was scorching hot! I mean not just a little hot, enough to burn my finger! So my immediate thought was I must have installed the motors wrong or they were defective. The props looked fine, spun fine and flew fine but both CW motors were way too hot after flight. I tried calibrating, inspecting for shorts etc. Luckily (on a whim) I tried a new set of props (same cheap ones but different color). Voila! Motors are now just as they should be. My advise is always check your motor temps post flight after installing new props OR after a crash! OEM or not! I hope this is helpful to all! Happy flying!
 

xcrost

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Thought I should post a pic of the faulty props. Can you "see" anything wrong? My theory is that the hole is too big on 2 of them and the shaft would slightly spin inside during flight causing the motor to overheat. Any other ideas what could cause this??


20190202_195432.jpg20190202_195620.jpg
 

Guorium

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good guess but I would imgine the props could fly off easily if they spin relative to the shaft. Thank you for mentioning such issue though. Defo check those temp with new props.
 
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volate!lo

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Thought I should post a pic of the faulty props. Can you "see" anything wrong? My theory is that the hole is too big on 2 of them and the shaft would slightly spin inside during flight causing the motor to overheat. Any other ideas what could cause this??


View attachment 3023View attachment 3024
If the holes were too big and the props would spin just a little they would work their way up and fly away. Ask me how I know...

My guess is the props have slightly wrong pitch. If its too little pitch they need higher RPMs to generate he same thrust. If too much pitch only lower RPMs are required, but the motor has to work harder to achieve these RPMs. Deviating either way from optimal pitch can cause hot motors.
 
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Sisul

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Thought I should post a pic of the faulty props. Can you "see" anything wrong? My theory is that the hole is too big on 2 of them and the shaft would slightly spin inside during flight causing the motor to overheat. Any other ideas what could cause this??


View attachment 3023View attachment 3024
If the photo is accurate, it looks like the left blade is about 1/4" shorter than the right blade. ?? Try checking the balance of one rotor by putting the end of a paper clip in the opening and holding the clip level.
 

Guorium

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If the photo is accurate, it looks like the left blade is about 1/4" shorter than the right blade. ?? Try checking the balance of one rotor by putting the end of a paper clip in the opening and holding the clip level.
Not sure what exactly u are describing. Care to share a vid?
 

Sisul

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Oh I mean ur instructions about prop balance check wasn't very clear to me.
Photo attached.
Put the Tello rotor on the end of an opened paper clip. Keep the wire as level as possible, then blow gently directly into the blades. Do this several times. If the prop ends up at random points each time, then it is fairly well-balanced. If one blade consistently ends up at or near the bottom, that blade might be too heavy. Solution: shave a little off the heavy blade (or put a small piece of scotch tape on the lighter blade) and test for balance again.tello rotor.JPG
 

Guorium

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Photo attached.
Put the Tello rotor on the end of an opened paper clip. Keep the wire as level as possible, then blow gently directly into the blades. Do this several times. If the prop ends up at random points each time, then it is fairly well-balanced. If one blade consistently ends up at or near the bottom, that blade might be too heavy. Solution: shave a little off the heavy blade (or put a small piece of scotch tape on the lighter blade) and test for balance again.View attachment 3039
Thank you! Very good method. I think I would polish the heavy side with fine sandpaper. Stiffness of the blade is very important so I hope polished blades wont behave weird.
 

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