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Aug 16, 2012, 03:06 AM
Registered User
South Africa, GP, Pretoria
Joined Jul 2003
398 Posts
Quote:
 Originally Posted by crashawk ... it's the watts that burns it up not the amps, it takes fewer amps at higher voltage to get the same watts as higher amps at lower volts. volts times amps equals watts, thats why you have to reduce the prop size so you do not exceed the max watts, thats when the heat gets excessive.
Crashawk
I can't agree with your statements above. It IS amps that causes a motor to heat up and burn the windings.
Look carefully at this formula: R x IČ = copper loss.
R (or Rm) is the resistance in one phase of an outrunner motor. So, amps squared times the Rm is what causes the primary loss in a motor, i.e. the main source of heat.
In outrunners, iron loss is usually much smaller than copper loss and can also be calculated: Io x volts, where Io is the no-load current.

Christo
 Aug 19, 2012, 11:57 AM Registered User United States, GA, Alpharetta Joined May 2011 37 Posts hi there, i would like to ask about number of windings, if BL motor specification state 14turns (12 teeth,14 magnets) , does it mean total number of turns on one line (on all 4 teeth), or number of turns on one tooth, please ?
 Aug 19, 2012, 11:58 AM Unicorn (Cordova)Memphis, TN Joined Jul 2002 1,815 Posts Turns on one tooth
 Aug 19, 2012, 12:13 PM Registered User United States, GA, Alpharetta Joined May 2011 37 Posts i tought so, but im going to rewind turnigy G15 950kV , and im not sure how. it has 22 x probably 32AWG in one strand , and when counting turns while unwinding it, it has 4 , 3.5, 4, 3.5 turns per tooth. Can`t find any information about this motor on the net, can somebody help me what gauge and turns per tooth i could use to get approx the same kV ? im thinking about 24-20AWG. stator diameter is 27mm and length is 28mm.
 Aug 19, 2012, 12:49 PM Registered User South Africa, GP, Pretoria Joined Jul 2003 398 Posts Usually, number of turns is "per slot", i.e. a 14-turn motor will have 7 turns per tooth. Have you ever wondered why number of turns are always even numbers? Putting 14 turns on a tooth (for a 14-turn motor) would give a Kv of half the desired value. Don't ask how I know.. Christo
 Aug 19, 2012, 01:12 PM Registered User United States, GA, Alpharetta Joined May 2011 37 Posts nope, i never wondered why numbers of turns are alwayz even, because they are actually not. for example scorpion`s motors - S3014-1040 13turns, S3014-1220 11turns, S3026-890 7 turns.. btw, what is slot ? two adjacent teeth in your example? one wire(phase) goes around 4 teeth on 12 pole motor, isn`t it ? im sorry about my beginner`s questions, but i can`t find any info about this numbering. so, in 14T motor, it means 14 turns per tooth, or per slot (two teeth) or per all 4 teeth in one phase ?
 Aug 19, 2012, 01:30 PM Jack USA, ME, Ellsworth Joined May 2008 15,564 Posts delete me... Last edited by jackerbes; Aug 19, 2012 at 08:32 PM.
Aug 19, 2012, 02:07 PM
Registered User
South Africa, GP, Pretoria
Joined Jul 2003
398 Posts
Quote:
 Originally Posted by xener nope, i never wondered why numbers of turns are alwayz even, because they are actually not. for example scorpion`s motors - S3014-1040 13turns, S3014-1220 11turns, S3026-890 7 turns.. btw, what is slot ? two adjacent teeth in your example? one wire(phase) goes around 4 teeth on 12 pole motor, isn`t it ? im sorry about my beginner`s questions, but i can`t find any info about this numbering. so, in 14T motor, it means 14 turns per tooth, or per slot (two teeth) or per all 4 teeth in one phase ?
Sorry, I was referring to the older version Scorpion motors, not version-II. Look at this page. All the motors are even-numbered. Obviously, Scorpion are now doing LRK-winds, where only every alternate tooth is wound and therefore the full turn-count can be put on one tooth. Can someone please confirm this.

LRK winds are not very common these days and I have never seen any Turnigy motors being wound this way. Most outrunners are wound dLRK or "distributed LRK" where every tooth is wound with half of the turns of the turn-count.

Yes, slot means the valley between teeth.

Christo
 Aug 19, 2012, 02:57 PM Registered User United States, GA, Alpharetta Joined May 2011 37 Posts thank you both for answers to my doubts. original G15 is dlrk, delta , now im thinking about star with one wire if it would be possible, Im going to check some conversion tables to check what i can do. Some kV up is not a problem, its a motor for WWII plane. S3014-1040 V2 is running in my Katana S30, and every tooth is wound, its not LRK. But seems like not every manufacturer count turns the same.
 Aug 19, 2012, 03:39 PM Jack USA, ME, Ellsworth Joined May 2008 15,564 Posts delete me... Last edited by jackerbes; Aug 19, 2012 at 08:33 PM.
 Aug 19, 2012, 04:35 PM Registered User United States, GA, Alpharetta Joined May 2011 37 Posts my apologies , this is my new thread: http://www.rcgroups.com/forums/showthread.php?t=1715068 jack, please move your valuable posts there, please. and of course, i would like to ask thread owner to delete my posts, please.
Aug 19, 2012, 04:49 PM
Registered User
South Africa, GP, Pretoria
Joined Jul 2003
398 Posts
Quote:
 Originally Posted by xener S3014-1040 V2 is running in my Katana S30, and every tooth is wound, its not LRK. But seems like not every manufacturer count turns the same.
Interesting. I know for a fact that Scorpion counts winds per slot and not per tooth, because I've wound some Scorpion kits to factory spec and confirmed this myself.

If they do 13 winds on the S3014-1040 V2 motor, then they must have found a way to do half turns per tooth. I've thought about it before, but never tried it myself. "Half turns" will give you more Kv possibilities. It's a great idea if it can be done.

Christo
 Aug 23, 2012, 06:56 AM Registered User United States, GA, Alpharetta Joined May 2011 37 Posts hello again, i have one more question, if i can`t fit two 20AWG wires , can i use combination of one 20AWG+one 21AWG ?
Aug 23, 2012, 07:08 AM
Registered User
South Africa, GP, Pretoria
Joined Jul 2003
398 Posts
Quote:
 Originally Posted by xener hello again, i have one more question, if i can`t fit two 20AWG wires , can i use combination of one 20AWG+one 21AWG ?
Yes, I've mixed wire gauges many times. However, there are people who will tell you that you shouldn't do it. It works for me.
Christo
Aug 23, 2012, 10:20 AM
Jack
USA, ME, Ellsworth
Joined May 2008
15,564 Posts
Like Skylar says, that will work fine.

As long as the two strands are soldered together at the ends you have sum of the resistance of the two wires in parallel. We don't really care what the value of that is, it is just that the more copper there is in the phase the lower the resistance will be and the higher the current can go.

We were joking around about it once and I designed a closer to perfect wind, it would be made with large and small wires with each succeeding smaller wire being sized to fill the gap left by the previous wires. Each strand would have three wires in my design, you can see a cross section of it in the image. No one does actually does that of course, can you imagine trying to keep all that in place as you worked?

And, did you know, there is such a thing as square motor winding wire so as to leave less unused space?

Jack