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Bad motor? (again) Bad ESC maybe?

Posted by Steve Castano on July 22, 2011 at 8:13pm

I thought I had a bad motor but......

 

When I first start the quad it seems like everything is fine. (maybe because its all cool?) Then I can fly around for a few minutes..... seems to stay in the air with no problems, fairly level, ALT_HOLD works (baro, not sonar) and things seem to fine.....

 

Then I land for a minute to take a break, re-get my bearings (still learning to fly this crazy thing) and when I go to start up, my front left motors (in x mode) seems like its struggling. It bounces the prop back and forth a bit, maybe makes a 1/4 or 1/2 turn..... then just give us. Meanwhile, all the other 3 motors are rocking along just fine.

 

I thought I had a bad motor, so I replaced that and on the first flight with the new motor.... EXACT same problem.

 

Anyone seen that before? Does that sound like an ESC? Loose wire? crappy soldering on the power distro board?

 

(note: in the video below... the motor isn't spinning really.... its bouncing a few degrees each time then giving up)

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Replies

  • Steve Castano July 30, 2011 at 2:49pm

    OK, so I've replaced the ESC now, done a full ESC calibration..... and the motor attached to the new one I just put in is definitely spinning much slower than the other motors!

     

    Any ideas?

     

     

  • roger July 27, 2011 at 5:14am

    Steve,

     

    Just got my 880 motors couple of days ago. After installing the motors with the quad and firing up the APM/IMU one motor was looking like what you're having. Kind of dismissed it as bad esc calibration so went through the calibrations with no improvement. Still thinking the esc as the problem, swapped the esc connection and everything worked fined with the particular motor. Just by chance though, the setup was disrupted a bit (wiring-wise) that the motor was acting up again. Re-attached the problematic motor with the corresponding esc, fired up the throttle and at the same time, holding tighly solder connections. Guess what, one of the cables under the shrink tube got loose. You will not know since the shrink tube kind of give you the impression of solid connections! After I sliced off the shrink tube, there was the problem in front of me. So if you are that desperate, checking all solders under those shrink tube may be a lot of hassle but it could reveal the problem ... or not ... cheers.

  • Steve Castano July 26, 2011 at 7:25pm

    Looks like I'm taking advice from a bunch of people. I've order up some spare 30Amp ESC's to try that, I'm going to look at powering the APM with its own BEC also: http://www.experiencerc.com/store/castle_peak_cseccbec-p-2731.html

     

    Then we'll see where it goes from there. Everything should be here for this weekend.... I'll troubleshoot, test, assemble and hopefully get some flying time in and can report on temp, voltage, etc.

  • Jim Phoenix July 26, 2011 at 1:27pm

    Try this: Remove the props(!), arm the motors and give it just a bit of throttle, the "bad" motor will jump back and forth, try moving the bullet connectors around for that motor, see if the motor starts to run OK - if that happens, solder your bullet connectors together. I did that after months of intermittent motor problems (and replacing ESC's, etc) and haven't had the problem since.

     

    Jim

  • Cronselaar July 23, 2011 at 1:21pm
    I too have exactly this problem... I again thought it was the motor and suspected the bearing as the motor came to a sudden stop, luckily the copter escaped any damage. I oiled the motors(I would suggest this to all) and the problem seemed to go away... I flew it again and now 2 flights later i agian have a problem on the same arm. This time the ESC did the startup beeping after i armed the motors and the other started spinning... So? could anyone suggest a plan of action?

    regards
    Gerrit
  • Todd Hill July 22, 2011 at 10:24pm
    Also, some ESCs' will go into a type of auto shut off when they get too hot. If your ESC for that particular arm is getting too hot to touch this could likely be the case. An unbalanced frame, or underrated ESC to motor setup could also be likely problems contributing to overheating. Are the props that you are using within the suggested prop range? They look a little big. Overloading your motors with a larger than recommended prop will most certainly induce overheating, and possible burnout.
  • Todd Hill July 22, 2011 at 10:12pm
    If you have replaced the motor check the ESC. It looks as if you have some bad FET signaling from the ESC to the motor. Are you using bullet connectors between the motor and ESC, or did you solder them together?
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