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Old 08-06-2006, 08:07 PM   #1
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Default What makes a brushless motor cog ?

I have been having problems with my Neo 1 Star........ and it has cogged on me a few times..... I am running it in a B4 with an LRP Sphere ESC....... 21 / stock...... (gears)............(81 ??)


Today I went around the track for 1 lap to get over the line... then I went back over the line to start the race.... when I went to go.... nothing.... the motor was cogging..... I have had problems off and on......


anything ???


Thanks
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Old 08-06-2006, 08:13 PM   #2
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I don't know, but I do know that the reedy motors have been having a lot of trouble in general. I think one of the problems are the magnets are shifting or something like that. Could be your problem.
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Old 08-06-2006, 09:38 PM   #3
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could be your batteries...

have you tried cleaning the motor and lubing the bearings? that could cause cogging maybe.
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Old 08-06-2006, 11:12 PM   #4
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Yeah if your batteries aren't giving it enough power that can happen, also gearing can have a lot to do with it. Im not farmiliar with the sphere but there should be a setting where you can change the starting power from low, to medium, to high. Also try updating the firmwear.
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Old 08-07-2006, 06:36 AM   #5
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Sorry guys, not much of an elect guy any more so I got to ask what is cogging?
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Old 08-07-2006, 07:36 AM   #6
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Cogging is a phenomenon where a brushless motor won't respond to a throttle input, and the car stutters instead. It is mainly an issue with sensorless systems like Castle Creations, rarely an issue with the sensored systems used by LRP and Novak.

Sounds like the original poster either has a faulty/undercharged battery pack or a problem with the system.
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Old 08-07-2006, 10:12 AM   #7
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RTFM on the ESC and change your settings to low power.

cogging can be an issue with any brushless system that is not configured/programmed correctly.
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Old 08-07-2006, 10:45 AM   #8
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Ah........I see, it has a lean bog!

Thanks guys
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Old 08-07-2006, 11:25 AM   #9
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Steve...
Which power mode are you running your Sphere on ?
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Old 08-07-2006, 05:42 PM   #10
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I am running in the mod mode........ but i also had the problem in the limited grip mode.......


Here is the thing that I dont understand......My batteries were charged up..... put the body on.... put car on track.... drive it around 1 lap to go over loop...... then drive back over loop....... wait about 30 ~50 seconds...... then the car would not go....was cogging....... had someone push it... to see if i could make it go.... nothing........ take it back to pits...... reset the speed control..... all the settings..... still cogging.....then after messing with it somemore.....it works....dont know what i did to make it work... but it works..... so i drive it a few laps... then i have to take it off because of the next race starting...





Should I be running some sort of capacitor ??????
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Old 08-07-2006, 07:44 PM   #11
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try

1st recheck your programing of all the power modes...

2nd check for a loose connection on the sensor harness plug..
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Old 08-08-2006, 06:39 PM   #12
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how i understand it is that a sensorless controller assumes that the rotor is in the position that it is supposed to be in, when it is not then the motor cogs. in a sensored system the speed control knows exactly where the rotor is and that is why they shouldn't cog
that is how i understand it but i could be totally wrong
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Old 08-10-2006, 07:00 PM   #13
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Hi everyone, saw and sosidge pretty much got it right. Cogging is cuasing by the motor is not reving up fast enough to be in sync with the controller. It should only happen to the sensorless system, unless there is something seriously wrong with the sensored system.

It basically happens when you apply the throttle, the controller will energize different pole of the coils in the can to keep the motor turning. In other words, there is a time of how fast the controller change the to next zone. The controller assumes the motor will keep up with the timing, but when car is over geared, or the battery doesn't provide enough power. This cause the motor to bog down.

On the sensored base system, the controller is waiting for the feedback that's coming from the hall sensors. So, it doesn't assume the position of the rotor, which shouldn't have any cogging problem. I would advise you to first make sure all the sensor wires are connected and not cut. Second, try a smaller pinion, maybe 2 to 3 teeth smaller.

BTW, there are several times in the magazine, Hi-torque's R/C car, the editors completely mis-understood the meaning of cogging. Somehow they get the idea of cogging as the drag brake from the brushed motor.

Good luck
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Old 08-11-2006, 12:18 AM   #14
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Try this...

Remove the rotor from the can, shine a torch lite into the base of the can and you should see 3 indentical hall sensors. These hall sensors are little ic chips with 2 of its leg soldered to the pcb board of the motor base. If you can't find 3 identical hall sensors, ie just one or two, then you have a damaged can. Loosing one hall sensor will cause cogging as the motor system is not able to detect the rotor position to give power accordingly.

I hope this helps. I am not an expert but with some minor experience to help.

Cheers,

PS: To remove the rotor, remove the three long screws from the front of the motor, not from the base where the wires are soldered on.
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