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Help rewinding brushless motor

Jonawald

Dec 16, 2015
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Dec 16, 2015
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Hi, I have this DeWalt string trimmer with a big brushless motor and 40V power supply. It quit working over the summer. When I opened it the windings were discoloured and burned. I thought I would make an attempt at re-winding the motor. Well I have.

Now it stutters but does not turn. Where did I go wrong? I have a few guesses to lead the way. Can somebody help me connect the dots. I did some research and wired it in delta fashion as it was originally. I'm reasonably sure I have the pairs of poles done right. There are 6 poles with 23 wraps each.

first guess: I miss counted on some of the wraps and don't have exactly 23 wraps on each pole. My guess here is that the motor would still turn but not efficiently or maybe with less power than intended. Correct me if I'm wrong.

second guess: I have some of the poles wrapped in the wrong polarity. I was not sure if I should be winding all poles clockwise or all anti clockwise or if I should alternate poles. I'm not even sure if this matters. I tried to find an answer to this question before I started winding but could not find anything. Most likely this is the fault. If so can somebody clue me in on the proper way to do this.
 

73's de Edd

Aug 21, 2015
3,608
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Aug 21, 2015
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3,608
Sir Jonawald . . . . .

Hmmmmmmmmmmmmmm . . . . . I haven't heard from you since your great "relaxicizor" / " massage" chair escapades / fiasco.

Before I expend any more keystrokes . . . initially why don't you just look at this info . ..to see if its contained Edd-u- cational value doesn't fill you in enough for your task now at hand.
Initially, THANK goodness for your motor type having its LARGER physically dimensioned infrastructure . . . . . . none of those gnat sized RC propeller motors !
The first " how to refrence " WITH its additionally submitted link reference

+plus + even more at
Winding types:
http://www.bavaria-direct.co.za/schem...

Winding table:
http://www.bavaria-direct.co.za/info/


Another " how to " site
(BOY ! . . .hes ab-soo-rootley gots 1 of EVERY one that there is.

PLUS just a BLANKET search of ALL related info at :

https://www.google.com/search?sourc...&ved=0ahUKEwiSnubmksPuAhVKS6wKHQWBDSMQ4dUDCA0

Thaaaaaaassit . . . . .
BTW
since you initially did not provide much related info . . . .
How many stator pole pieces on the unit ?
Mike the wire to find what wire gauge it is ?
The number of turns found used on a stator ?

73's de Edd . . . . .


Always try to constantly evaluate the situation, so that you can stop talking before people stop listening.

.
 
Last edited:

kenny256

Jan 4, 2020
54
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Jan 4, 2020
Messages
54
The polarity of the windings must alternate or the motor will not spin. For example with a 3-phase brushless motor, there will be an alternating pattern for the six windings: A+, B-, C+, A-, B+, C- , where + and - refer to the start and end of a given phase. This gives the necessary magnetic field to the stator poles as they are energized by the drive inverter.

The curled right hand thumb rule is helpful to determine the polarity of a coil. When current is moving in the direction of curled fingers, then your thumb is pointing in the direction of the N magnetic field.
 
Last edited:

Jonawald

Dec 16, 2015
201
Joined
Dec 16, 2015
Messages
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Sir Jonawald . . . . .

Hmmmmmmmmmmmmmm . . . . . I haven't heard from you since your great "relaxicizor" / " massage" chair escapades / fiasco.


.
Thank you very much. As you can see I'm still alive and kicking I don't document all my shenanigans with electronics, but that was a good one. I'll take a look at your links and get it working.
 

Jonawald

Dec 16, 2015
201
Joined
Dec 16, 2015
Messages
201
And of course it worked perfectly. I don't know how I missed that I have to alternate poles. I also don't know why I didn't just know that. Either way, it was nice haring from you again. Thanks for the help.
 
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