When one motor starts slower than the rest.

Pumpkinguy

Pumpkinguy

Member
Have you ever had one motor that always starts slower than the rest? Your esc's are calibrated properly and even if you move the motor over to another esc it still has a "lazy start"?
I wanted to start a conversation on this and come to some type of consensus on the possible causes.
The first time this happened to me was on a heavy lifter. Not only would one motor start slower, it would rock the opposite direction once before starting. upon inspection of slow motion footage the motor in question would only turn about 1/3rd the speed of the other motors at hover. At the time I did not own a LC meter but I did take an ohm reading and got .01, 0.1 and .02. Highly inconclusive but I suspect a short across the coils. A short from one phase to another could be a possible cause of the motor momentarily wanting to go the other direction, or am I way off base here? (no esc damage on this one)

My second case of a "lazy starter"
350 sized quad. From day 1, one motor had a slightly slower start which got worse over time. finally it got to the point where it just did a couple 1/2 turns, motor heated up like a sob, magic smoke came out and both the motor and esc were done.

Lately, when I unbox a new motor I pull off the bell and take inductance readings of each phase and make notes. Maybe I will identify a bad motor from the start?????

Regardless of the suspected cause, whether it is motor or esc related or a combination of both I will not be flying any rig in the future that has a chronic slow starting motor. I believe that failure is inevitable.

Input, thoughts, comments are all welcome.

Chris
 

C

Chalagi

Member
Mine did that on my Tarot 680MM and I found out that I had 2 motors that had the bearings froze up. Those puppies would not spin period.
 



Bartman

Bartman

Welcome to MultiRotorForums.com!!
keep in mind these motors are being made in huge quantities, an occasional bad one is the price we pay for having them available at such affordable prices. quality control will usually be better in the higher priced brands making it less likely you'll have even one "lazy" motor as you go along.
 

Pumpkinguy

Pumpkinguy

Member
Bartman said:
keep in mind these motors are being made in huge quantities, an occasional bad one is the price we pay for having them available at such affordable prices. quality control will usually be better in the higher priced brands making it less likely you'll have even one "lazy" motor as you go along.
Click to expand...

I agree on this.

Millions and millions of feet of stator wire that is manufactured and processed thru machines with dozen of feed rollers. I guess it's likely that there are nicks or rubs in the insulation during manufacturing of the wire itself or during the winding process of the motor.
 


F

fengshuidrone

Guest
Both are manufactured in China. (I think ALL brushless outrunners are made there.) Bad karma. Sorry.
 


Bartman

Bartman

Welcome to MultiRotorForums.com!!
keep in mind these ESC's are being made in huge quantities, an occasional bad one is the price we pay for having them available at such affordable prices. quality control will usually be better in the higher priced brands making it less likely you'll have even one "lazy" ESC as you go along.

:D

i keep forgetting to upload the new emoji library, the selection here is lame!
 

Pumpkinguy

Pumpkinguy

Member
fltundra said:
Being that it's two completely different motors, I would suspect ESC's are the issue.
Click to expand...

I don't think you understood my original post. 2 different rigs. In both cases I tried motors with other "known to be good" esc's and the same problem existed. It was not a esc problem.
 

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