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Oct 14, 2007, 03:41 PM
Registered User
fr4nk1yn's Avatar
Thread OP
Discussion

Rewinding Emax CF2805 & CF2822


With Timochris giving me inspiration I took apart a perfectly "good" unused.

Twelve Tooth stator, 14 magnets in bell. I did not take a measurement of of stator diameter or width
Wire was 3 strands of what I assume to be 30g, they measured .0095".
Most teeth had 15T while, if I counted correct, 2 had 14T and 1 had 16T.

Recommendations on a rewind that will have similar performance, better efficiency and if it can take a couple more amps that'll be great too. I'm not looking for too much (;

I'll be driving over to the local electronics store to see if they have any 24g enameled wire. In case they don't RS does have a bundle with 22g and 26g.

Thanks.

-edit-:
WARNING: I'm doing a good amount of number fudging here.

Taking the test data from Drive Calculator and plugging it into MotoCalc for a reference the numbers come out as:
  • 2739kv
  • 1.7A
  • .207Ω

Calculating 3 strands of 30awg as 25.5 and the new wind of 17T of 24 MotoCalc suggests the motor efficiency will be a whopping .3% better.
If I punch in the numbers with 15T of 22awg the efficiency is 4% lower.

I'll assume this is due to the fudging(?).
Last edited by fr4nk1yn; Mar 29, 2009 at 11:14 PM. Reason: I guess my new thread was merged?!?
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Oct 15, 2007, 07:03 PM
Registered User
fr4nk1yn's Avatar
Thread OP
I bought some enameled 24awg wire from the electronics shop today and started winding.
There's NO WAY I'm gonna get 17T of it on the stator.
I was able to get 2 stators wound next to each other with 13T once. I couldn't repeat it a 2nd time.

Can I use 9T or 10T and terminate the dLRK Wye?

Another thing I think I'm missing. When the direction of the 2nd dLRK tooth changed the tooth gets 1/2 wind less than the 1st(?). Is that right?
Oct 16, 2007, 10:45 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
LRK or DLRK does not matter much. DLRK is better for thin motors, LRK for longer motors.

17wind in delta is equivalent to 10 winds in wye. Use the thickest wire possible or wind 2-3 in parallel if that's easier.
The only way to get efficiency up by rewinding is by getting a better statorfill i.e. with copper.

About winding wire
Go to your local friendly motor/transformer rewinder/refurbisher or repair shop. Excellent quality, all gauges, penny stuff, you'll probably get it for free if you bring your motor along. They love it when they can handle a motor without an overhead crane And maybe let them have a spin with your plane once you finished your motor? You know, in case you need wire again for your next motor

In general:
Whether you use star or delta makes no difference, you can get the same motor (Kv, Kt, Io, Ri) with both configurations: 17 winds in delta/triange is the same as 10 winds in star/wye (factor 1.7 = v3 ). (Wire diameter has to be changed accordingly of course)
However, delta is a closed circuit all by itself, differences between the wound phases (#winds, wire-length or -diameter) may lead to differences in the voltages induced in the coils/phases. Useless circular currents will flow through the delta circuit, which leads to higher temperature and lower efficiency.
Therefore: star/wye.

About (D)LRK
12 statorpoles, 6 (lrk) or 12(dlrk) wound, 10 or 14magnetpoles:
DLRK winding tutorial
https://www.rcgroups.com/forums/showthread.php?t=736580
LRK winding
https://www.rcgroups.com/forums/showthread.php?t=523039
http://www.torcman.de/peterslrk/index_eng.html
http://www.torcman.de/motoren/manual...o_200e_scr.pdf


Excellent motor building articles by Brian Mulder, a must read, will prevent you from asking a lot of questions you even did not know you were going to ask
http://www.southernsoaringclub.org.za/
-> Articles by SouthEasterners.
-> Electric Motors - part 1-5

Do-it-yourself motor homepages, manuals/tutorials, checks and tests in this motor builders tips and tricks thread. The checks and tests may save you from frying your controller or motor. Thread is active, bookmark it for future reference and subscribe to it:
https://www.rcgroups.com/forums/showthread.php?t=240993 (sticky thread, at top of subforum)


Vriendelijke groeten ;-) Ron
• diy motor building tips & tricks
• diy brushless motor discussion group
• Drive Calculator download & discussion group
• int. E fly-in & diy outrunner meet, Nijmegen, the Netherlands
Oct 17, 2007, 11:15 AM
Engineer for Christ
IBCrazy's Avatar
Quote:
Originally Posted by MiseryQ
I bought some enameled 24awg wire from the electronics shop today and started winding.
There's NO WAY I'm gonna get 17T of it on the stator.
I was able to get 2 stators wound next to each other with 13T once. I couldn't repeat it a 2nd time.

Can I use 9T or 10T and terminate the dLRK Wye?

Another thing I think I'm missing. When the direction of the 2nd dLRK tooth changed the tooth gets 1/2 wind less than the 1st(?). Is that right?
I would advise winding as a 10T Wye termination. The Wye uses less turns and from experience, my speed controllers sense the position of the motor better. A good wire to use is the Gobrushless newbie wire. 26 AWG is good for up to about 12 amps. 24 AWG is good for almost 20 assuming adequate cooling. Many motor winders (including myself) prefer to use a single strand of the largest gauge you can fit on the stator rather than multiple smaller strands. You might find that using 2 strands of 26 AWG works best for you though.

In addition, you might find it easier to use the standard ABCABCABCABC winding at first rather than DLRK.

-Alex
Last edited by IBCrazy; Oct 17, 2007 at 11:39 AM.
Oct 17, 2007, 12:16 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
For ABCABCABCABC you need eight or 16 magnetpoles. This motor has 14 magnetpoles. Furthermore, LRK makes for smoother running.

Vriendelijke groeten Ron
Oct 17, 2007, 06:54 PM
Engineer for Christ
IBCrazy's Avatar
Quote:
Originally Posted by Ron van Sommeren
For ABCABCABCABC you need eight or 16 magnetpoles. This motor has 14 magnetpoles. Furthermore, LRK makes for smoother running.
Are you sure you can't do the ABCABCABCABC? I have wound several 12 pole stator, 14 magnet rotor motors this way. I did it that way before I discovered LRK winding. I know DLRK is smoother, but is it more efficient too?

-Alex
Oct 17, 2007, 07:08 PM
Registered User
fr4nk1yn's Avatar
Thread OP
I getting a lot of practice. I'm winding and unwinding working on technique. My fingers hurt.
So far not so good. I can get some good winds and some not so good.
With 24awg I can't get more than 11T. With 22awg I can get 7T but it looks sloppy.
I get 6T on the first pass which makes the wires angle down for the 2nd tooth.
Then I'm only able to get 5T on the 1st pass.
I also tried 2 strands of 26awg and was able to get 8T. That wind is nice and neat.
I think I'm gonna go for the 7T/22awg wind.

Oct 17, 2007, 08:05 PM
Registered User
fr4nk1yn's Avatar
Thread OP
Quote:
Originally Posted by IBCrazy
Are you sure you can't do the ABCABCABCABC?
-Alex
On 2nd thought I'm not sure what this chart says.
Oct 18, 2007, 08:47 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
Quote:
Originally Posted by IBCrazy
Are you sure you can't do the ABCABCABCABC? I have wound several 12 pole stator, 14 magnet rotor motors this way. ...
For from optimal.


Quote:
Originally Posted by IBCrazy
... I know DLRK is smoother, but is it more efficient too? ...
(D)LRK is more efficient.

Quote:
Originally Posted by MiseryQ
On 2nd thought I'm not sure what this chart says.
It says to use different winding diagrams for 12statorpoles/14magnetpoles and 12statorpoles/16magnetpoles.

Vriendelijke groeten Ron
Mar 06, 2009, 02:15 AM
Registered User
hello. with the orginal motor, is it possible to run a 6x4 prop on 3 cell safely? If not what are the parameters i should use it in with 3 cell?
Mar 06, 2009, 08:40 AM
Registered User
fr4nk1yn's Avatar
Thread OP
No! I seriously doubt it would last long.
I settled on 11turns of 24g and that WILL turn a 6x4 prop on 3s with some amazing results. IIRC it put out 17ounces of thrust on my makeshift stand.

I normally use a Graupner 5,5x4,3 on it.
Mar 09, 2009, 04:21 PM
Registered User
How many amps is the 11turn/24g pulling with the 6x4 prop?
Mar 09, 2009, 05:04 PM
Usual suspect.
Yea, I'm curious about the amp draw also.
Mar 09, 2009, 08:22 PM
Registered User
fr4nk1yn's Avatar
Thread OP
I just looked back at my posts.

I don't know the amps at that thrust since I used an inline power meter.
When connected the thrust dropped to [email protected]
It needed a large battery, 1800 polyquest, to get the 17ounces.

Still my favorite motor. Hopefully not for long cause I just order a fc2822 to rewind (:
But then again I just ordered my FIRST "Blue Wonder" too.
Mar 10, 2009, 10:22 PM
Registered User
Hey MiseryQ, I just rewound that same motor due to receiving the wrong kV. It's far from optimal, but I'll try rewinding it again when I get some time. Here's my thread:
https://www.rcgroups.com/forums/show...highlight=2805

BTW, are you the same MiseryQ from the old days on the MegaSquirt forum? Small world! :-)


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