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Old May 19, 2010, 01:44 PM
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Carmichael, CA
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Quote:
Originally Posted by rodrigocunhars View Post
Truglodite!
Now I understand what you told me, I reboinar DT750 motor with 36 turns of wire 26 awg each motor stator. and I do like desenhologo below. am I correct?

http://www.powercroco.de/schemamodus12N_YY2.html
Yep, that's DLRK parallel-Y.

Kev
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Old May 19, 2010, 02:00 PM
Dave North
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USA, CA, San Jose
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Quote:
Originally Posted by Truglodite View Post
I upgraded to Excel 2007 recently, so looks like I need to redo those files using compatibility mode.
This is one of those times I'm pleased that I don't do windows!

Dave
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Old May 20, 2010, 03:40 AM
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Spreadsheet updated... err... postdated

I uploaded a compatible version of my spreadsheet:

http://www.rcgroups.com/forums/showa...2&d=1274343368

I also finished testing on my 3rd DT rewind; a DT700 this time, if that matters. The goal was improving on the 16T-D:

DT700-9x2T-21a-Y
Zippy-R 3s2000 (old)
alt/temp = 29m/24.1C

no load
10410RPM/11.39V/1.61A -> 914Kv

GWS 1060hd
8254RPM/10.68V/14.61A/33oz/76.3%
APC 10x4.7sf
7738RPM/10.49V/18.22A/39oz/77.0%
APC 11x7e
7288RPM/10.24V/21.27A/42oz/78.3%
APC 12x6e
7084RPM/9.98V/24.26A/50oz/73.3% <- requires high timing

Thrust measured on my stand, efficiency from latest DCalc.

Not nearly as impressive as 10x2T-21a-Y on 4cell, but it is a minor improvement to the 16T-21a-D. This stator had a ton of factory CA near the top of the heads; I was lazy and didn't pick it off. So unlike the 10x2, the 9x2 is doable with any given core.

Kev
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Old May 20, 2010, 06:53 AM
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Thanks, So I reboninar I speak as the engine was.
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Old May 20, 2010, 11:52 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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rodrico,

Are you saying you want to rewind the motor as it was? If so, the rewind in that starts on post #39 in this thread will do that:

http://www.rcgroups.com/forums/showt...=3#post8180335

that is called the Delta variation and is what I used on the motor I just completed.

Jack
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Old May 21, 2010, 02:52 PM
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Quote:
Originally Posted by jackerbes View Post
rodrico,

Are you saying you want to rewind the motor as it was? If so, the rewind in that starts on post #39 in this thread will do that:

http://www.rcgroups.com/forums/showt...=3#post8180335

that is called the Delta variation and is what I used on the motor I just completed.

Jack
how many rounds you used in your engine and which wire you use?
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Old May 21, 2010, 02:56 PM
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Okay, the time has come. I am going to rewind one of these for an APC12x6e. It looks like 16T 21AWG dLRK making 50oz+ is the winner... just a quick question:

I read that you can do unequal winds per half-phase to keep the wires neater... say 10-up and 6-down instead of 8/8... are there any negatives to doing this? Lost efficiency?

I'm going to order some 21AWG from goBrushless right now... can't wait to soup-up my DHC-2 -- and she might need the extra oomph once I add floats.
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Old May 21, 2010, 03:23 PM
Dave North
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Originally Posted by warhead_71 View Post
I read that you can do unequal winds per half-phase to keep the wires neater... say 10-up and 6-down instead of 8/8... are there any negatives to doing this? Lost efficiency?
In theory, yes. In fact, we've mostly just tested a single turn difference and it hardly shows up. But with something as radical as that, it might.


Dave
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Old May 21, 2010, 07:54 PM
Jack
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Quote:
Originally Posted by rodrigocunhars View Post
how many rounds you used in your engine and which wire you use?
I used 16 turns of 21 ga. wire.

The wind I did is a Distributed LRK wind with a Delta termination.

I see now that Truglodite referred to your wind as a "DLRK parallel-Y" when he answered your question so maybe you're doing something different than I did?

Sorry if I created any confusion.

Jack
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Old May 21, 2010, 10:41 PM
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Yes, we were discussing using 26awg, so I think parallel was the only appropriate way to go about it. FWIW, I added a diagram of parallel DRLK to my blog:

http://www.rcgroups.com/forums/attac...mentid=3256443

Cheers,
Kev
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Old May 22, 2010, 09:26 AM
Jack
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Thanks Kev,

And I got a look at the updated spreadsheet, that's wonderful! Thanks for that. I used OpenOffice 3.2 Calc for looking at that and it worked fine. That is a good no cost alternative for those of us that are not inclined to buy or acquire Excel.

When you guys talk about "unequal winds" I guess that relates to the number of windings in each layer of windings? Does having the layers equal make a considerable difference in performance or efficiency?

Jack
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Old May 22, 2010, 01:52 PM
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Jack, you're welcome! I use that spreadsheet so much that I figured the extra coding was worth it. Now my rewind 'sheets have 99% of the functionality the motorxlt 'sheets have. So I'm going to drop the motorxlt sheets and use the rewind sheet instead. There's no graphs, and it requires a little more work in the Eagle Tree software, but that's offset by having a complete list of sortable data in one file... just need to add a motor ID# column to do that.

As far as unequal winds per layer goes, I usually try and keep 'em even steven. Not that it makes a huge difference (probably won't see a difference in a bench test), but it's peace of mind that the phase lengths more equal. On extra packed winds I sometimes "cheat" if there's room left for one more turn on the bottom of the second layer, but no more than one turn... it's better than crowding wires near the top anyways. I figure if there's room for 2 more wires, might as well put one on each tooth.

Cheers,
Kev
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Old May 22, 2010, 08:34 PM
Jack
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Truglodite wrote:

"..Yes, we were discussing using 26awg, so I think parallel was the only appropriate way to go about it..."

I was thinking about trying to rewind a 22mm motor (EMAX BL2210/30) I fried a while back and just asked a question about the wire size to use for it here:

http://www.rcgroups.com/forums/showthread.php?t=1248742

If 26 awg or so is the appropriate wire there, would the parallel wind and Delta termination be a good choice there too? I looked for a discussion of the pro's and con's of series versus parallel but haven't found it yet. The term "parallel" there means the phases are connected in parallel right? As opposed to in series? Not to confuse any of that with parallel strands of course...

Jack
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Old May 22, 2010, 11:53 PM
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First thing I'd do with a burned backplate style motor is throw it out... j/k. Try and pull the stator off the bearing tube; heat with a soldering iron if it is stubborn. If you manage to do that without killing the motor, look closely at the insulation. If it's just discolored it'll be fine and you can just rewind it, but if the green goop is bubbled up or metal is exposed then you'll have to reinsulate. I use IC2000 ca glue to insulate stators; any black rubberized ca will work (gobrushless sells loctite brand rubberized ca). First scrape off the bad insulation, and apply ic2000 to the front and back of the stator, making sure to pad the corners well... without taking up too much room inside. Starting to sound like too much work? It probably is for that motor, especially when you could just get a new ax for under $10.

The term half parallel means 2 half phases are wired parallel to each other, instead of in series like a standard wind. The term full parallel means 4 quarter phases are wired in parallel.

Full parallel testing has shown poor results so far; I'm guessing it's due to high inductance, but there may be some very high Kv winds that would do well in full parallel. Half parallel is usually better when a standard wind would mean the wire is too thick to work with, and stepping down a gage would cost too much efficiency. In those situations going half parallel makes sense; you get to work with thinner wire so copper packing can be higher.

So say you want to do an 11T-23awg standard wind but it just won't fit, and dropping back to 11T-24awg would result in poor efficiency. Instead you can do 22T-26awg half parallel (or call it 11x2T-26). Electrically it's more or less equivalent to 11T-23awg (similar Kv, Io, and Rm), but it fits much easier. Technically 11-23 has a Cu packing of 2.805mm^2, 11x2-26 has 2.75mm^2, and 11-24 has 2.244mm^2. More copper is better, and in this case 11x2-26 is the highest copper packing you can get.

That clear as mud?

Hope that helps,
Kev
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Old May 23, 2010, 07:00 AM
Jack
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Joined May 2008
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"..That clear as mud?..."

It is getting a little bit clearer, slowly. I've been reading the articles over at GB and stuff and some of this is starting to soak in.

The stator came off of the back plate easy enough, I just heated the tube a little and it twisted right off.

Rewinding the 2210/30 is more about something to mess around with and motor winding education than economics. I also have a TP 2410-12 that has a shorted winding and I'm sort of looking at rewinding that one too.

I want to order some more wire for playing around with. I have some 21 now, looks like spools of 23 and 26 would be a good start as far as having some other sizes on hand.

I'm also trying to figure out/learn how to use the eLogger and get that going. It occurs to me now, I can leave the prop off of already mounted motors and just run them up with the eLogger to get things like Kv values and no load currents can't I? It would be a lot easier than using a drill press, a DMM, and having to measure the drill press RPM and the voltage there.

Jack
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