Motor Crackling Noise During Low RPM

Hello Everyone,

 

I'm finally got my jDrones Hexa assembled to my specification  (painted,  custom wiring, etc).  I began tuning it today,  so far so good.

 

I noticed that when starting up the motors, some of them,  on occasion, generate a sharp crackling noise.  Just quick little pops. It's almost sounds like they are misfiring.  As I crank up the motors to higher RPMs  the noise tends to cease for the most part.

 

Has anyone experienced this?  Is this okay?  Any solutions?

 

I have uploaded a youtube video,  at about 10 seconds in,  during initial startup you can hear the problem.

 

https://www.youtube.com/watch?v=aaRUlp-zkbk

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Replies

  • Do you have a definitive diagnostic about this issue? Is it something to worry about?
  • My diagnose: a bad connection in the wires.

  • I had the same problem, but it seems to have dissapeared since i upgraded to AC FW 2.1.

  • It's the low pwm frequence (8kHz) theese esc's run at combined with low kV motors that generate the clicking/crackling it seems. It allso generates the quite loud high pitched sound. Updated mine with better firmware that lets them run at 16kHz, result is no more klicking and no audiable whine

  • Developer

    Most of Brushless motors are doing small click click noise on lower rpms when they are driven from microcontrollers. I think only I2C based ESCs are not doing this. So it is rather normal to have it. It does not affect on flying in anyways.

     

  • About the poping motors, I had this too some time ago and the problem was a bad contact beeing made on the power connection from one of the ESCs. So check all connections as one of the plugs or soldering points may be loose. If after checking soldering points you realize they are all solid, may be from the motor itself or the ESC.
  • I am hearing the same poping / crackling sound in some of the 880Kv motors from jDrones.  I posted a list of this and other issues under the forum topic "Bad Motors".   I have had my fair share of problems with this particular motor.  Although today I have manged to get 3 flights in and whilst I hear this noise in one motor now  I cannot say it is anything too serious at this stage.  It would be interesting to see if there is more electrical interference / noise from the motors making the popping sound i.e is it mechanical or electrical in origin.  Since these are brushless motors is would not be arcing unless there is some other sparking.  I know another chap on the forum advised to watch screw lengths into the motor base.  But so far I have not seen this a problem with the Arducopter frame and motor mounts.  It is strange not all motors in agiven batch make this sound.

     

    I know for instance jDrones just started using a new type of bearing in the latest batch of motors.  Probably best to drop them a line and let them know your concerns.  Jani is very helpful in email replies form my experience.

     

     

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