Bad ESC damaging motors?

[trimmkm]

I've built a 180 size quad to fly with my son, but I'm having a motor issue. I'm using parts I had around the work bench, or picked up from other pilots. I'm using DYS SN20A ESCs and BE1806 motors. One motor would stutter at low speed. Then the motor wouldn't stay synced at any speed. When I tested the motor on a second ESC, it showed the same behaviour. I pulled the motor apart and found thread wound around the shaft between the C-clip and bearing, and burnt windings. I chocked it up as a bad motor (it was "slightly used" when I got them after all).

I replaced the motor, and the quad flew great for several batteries. But now the replacement motor (with the original ESC) is showing the same stuttering at startup. Is it likely that the ESC is the culprit, and is burning out the motors?

I have a new ESC and motor ready to install, but wanted some opinions on the root cause before I burn up more components.

Thanks in advance.

 

[Bricks]

Is it possible the timing on that one ESC is wrong, not sure of those particular ESC but many you can change the timing.

 

[Javiester]

si, es posible
si uno de los transistores mosfet de potencia del esc esta en cortocircuito te pasara la tension continua de la bateria directamente al bobinado del motor quemandolo
puedes comprobarlo conectando un voltimetro o polimetro en medicion de tension continua en los cables de salida del esc
tiene que marcarte cero voltios

Yes, it is possible
if one of the mosfet power transistors of the esc is shorted you will pass the DC voltage of the battery directly to the motor winding by burning it
You can check it by connecting a voltmeter or polymeter in continuous voltage measurement in the output cables of the esc
you have to dial zero volts

 

[trimmkm]

Thanks for the replies.

Brick, I confirmed thorough BL_Heli configurator that all ESCs are running the same firmware version (14.7 I think) and the timing is the same on all four (as read by the configurator).

Javiester, I'll try that before removing the ESC, thanks for the suggestion.

 

[cranialrectosis]

Definitely test as per Javiester's instructions.

I find that stuttering motors is most often caused by a loose solder joint between the ESC and the motor itself. Sometimes screws that are too long interfere internally with the motor or crashes loosen up the windings as well. It is common for some motor manufacturers to coat the motor leads with enamel. This enamel must be removed before you can solder a motor to an ESC. This also is a common issue that causes stuttering motors and burnt out motors.

If you have a stuttering motor check the solder joints and check the leads for enamel. Look closely at screw lengths and look for loose windings if you have ever crashed with the motor that is stuttering.

I also recommend that after you use a soldering iron and before you connect a lipo directly to your copter, you smoketest with a smokestopper.