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Old Dec 05, 2012, 02:01 AM
hooked13
Joined Dec 2012
11 Posts
Help!
castle thunderbird 54

I have a problem with this esc in that when I plug it into my 2 brushless motors using 3.5 bullet connectors (power 25 1250kv and OS .25 1200kv the motor does not spin freely. What I mean is that I can spin both my motors freely (by hand) not connected to the esc but when connected there is friction during rotation or what seems to be friction. I thought there was something wrong with the motor but the power 25 is one day old. To test out my theory on the thunderbird esc I connected both motors to an eflite 60 amp esc that I have laying around and both motors spin freely as they should with no friction of any kind. So my questiion is what could the problem be or is this a normal action from a castle esc? This is the first castle esc that I have owned. I am no expert but I do know that there is something wrong.
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Old Dec 05, 2012, 07:11 AM
Jack
USA, ME, Ellsworth
Joined May 2008
16,690 Posts
There is an effect called " cogging" where the magnets passing each other generate counter forces in the other magnets that can be felt as the motor is turned by hand.

In most cases, the motor will not spin freely at any time, there will always be some cogging effect. The forces and evenness of the cogging effect will change with the motor not connected to anything, it will change again when connected to the ESC, again when the ESC is powered up, and the settings you have chosen for the ESC can change it even further.

The lightest and most evenly spaced cogging will normally be felt when the motor is not connected to the ESC and all three motor leads are shorted together.

How are you connecting two motors to one ESC? That normally will not work because the ESC reads the back EMF from the motors to work right and control motor RPM. So each motor has to have it's own ESC.

Jack
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Old Dec 05, 2012, 09:35 AM
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Mark Wood's Avatar
United States, CA, Bear Valley Springs
Joined Feb 2000
26,191 Posts
You can't use two brushless motors on one esc. They need individual escs.

mw
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Old Dec 05, 2012, 09:44 AM
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tacx's Avatar
United States, MI, Macomb
Joined Apr 2009
2,484 Posts
He may not be connecting two at a time. But, the way he stated it sounds like it?

hooked,

I have the same ESC and experience the same condition. After reaserching I found that this is not a problem.
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Old Dec 05, 2012, 10:52 AM
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pilotpete2's Avatar
The Northeast Kingdom, Vermont
Joined Jun 2004
5,156 Posts
Definitely not a problem. Just a Castle Creations thing
What you feel is the ESC's brake action kicking in when power is removed from the ESC. Doesn't matter if the brake is programmed or not.
You'll notice that the braking action disappears as soon as the battery is reconnected.
Pete
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Old Dec 05, 2012, 12:06 PM
hooked13
Joined Dec 2012
11 Posts
seperate

Sorry if I made it seem like i was connecting 2 motors to one esc. That is not the case. I am connecting them seperately. One esc, one motor. I do understand the braking that the esc may have and if that is a castle creations or thunderbird thing then great. When battery is connected or not connected there is that friction (braking) action whether there is power or not. The motor does turn normal with power on but it seems as there is tension. Internals are all ok. Bearings and everything.
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Old Dec 05, 2012, 12:24 PM
hooked13
Joined Dec 2012
11 Posts
Thanks and it's good to know.
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Old Dec 05, 2012, 02:27 PM
Jack
USA, ME, Ellsworth
Joined May 2008
16,690 Posts
Unless the magnets have lost all or nearly all of their magnetism (over heating can cause that) you will always feel some cogging.

The motor will not spin freely without a prop on, it will spin a little more with a prop added because of the weight of the prop. If you have more than one more they will all have some cogging. Some of the smallest motors will have the most strongly felt cogging.

If you connect a multimeter to two of the motor leads you'll see you are generating an AC voltage when you turn the motor by hand, that is what is causing the magnets to "fight" each other a little give the cogging feel.

Jack
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Old Dec 05, 2012, 03:04 PM
hooked13
Joined Dec 2012
11 Posts
Thanks for the explanation. I understand much better now. I did connect the motor, esc and battery and the cogging actually wasn't there. I thought something was wrong when in reality my esc shut my motor down do to overheating. Thanks again.
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