Discussions

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?
Brian Boyle July 27, 2011 at 1:25pm

so for whats its worth. i just replaced the brand new ESC i put on last week and i am good and stable again. so i must have got a bad ESC. Luckily i had purchased two.

Bummer.

But THANKS for all the Devs... this is the coolest *hi& ever!
Paul July 27, 2011 at 7:54am

Tried setup again, radio set ups fine all original jdrones build with soldered esc. Still cant arm. Will try arduino, just got to figure that out now. I really like to use mission planner and was always working. Is there a way to totally reset/wipe clean the board and start again or that EEPROM is the best/only way?
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
Paul July 26, 2011 at 5:05am

hey guys,

would any one of you know why on a cold boot and first arm the motors start up automatically even though throttle is at 0? the issue goes after a few seconds and arm and disarm then functions as normal and it seems ok. is it hardware or should i run the setup again via mission planner?
Brian Boyle July 26, 2011 at 4:06am

sorry, so you thin that the brand new ESC may be the culprit? it just seems a little odd to me that a brand new device could exibit the exact same behavior as the one that was replaced. on the positive side that would be better then replacing the APM.

if i have a defective ESC that i just got, can i get a replacement?
Brian Boyle July 25, 2011 at 6:59pm

you know, this is strange. I also have this problem. i have one motor that does not work right. this is a new problem. i have the stock ESCs and the 850 motors with the 10 inch props. so just about everything is "stock" and one day the left motor seems to stutter randomly. some times it will start up just fine and others it stutters and i have to pump the throttle until it starts. i have replaced the motor and the ESC with brand new ones with no change in the behavior.

strange eh? i am now at a loss for what to try next.
James Roney July 24, 2011 at 10:37pm

Drop the prop size to 10x4.5. You cannot run 12x4.5 on a 30A controller, the motors peak to around 40/43A. You will loose aprox 220g of thrust per motor but still have more than sufficient thrust.