is there any significance to motor windings thickness?

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is there any significance to motor windings thickness?

Postby emaayan » Tue Oct 15, 2013 4:01 am

i'm trying to compare to motors, the first is from ecospeed (on the left) , and cost around 500-600$ the second is from CogHog for around 180$, the first should be able to handle about 1000-1300 watts, while the second is only rated to be 600..

Image

the only major difference i see is that the windings on the left (ecospeed) is thinner then the ones on the right, so could that make a difference?
Trek 7.7 fx, 22.5" frame, 38x700c,10 gears.
ecospeed mid drive 1300 watt engine, max speed 45 kph.
battery1: 48v 14 ah, frame mounted battery, range 40km.
battery2(spare) 52v 10ah frame mounted bag, range, 30km.
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Re: is there any significance to motor windings thickness?

Postby Miles » Tue Oct 15, 2013 4:03 am

No, you can't tell anything from the winding gauge on its own.
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Re: is there any significance to motor windings thickness?

Postby Hugh-Jassman » Wed Jul 01, 2015 1:14 pm

would the Eco-speed motor handle less amperage at a low voltage? or the other way around?
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Re: is there any significance to motor windings thickness?

Postby Miles » Wed Jul 01, 2015 1:22 pm

It would require a lower level of amps but a higher level of volts, for the equivalent output
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Re: is there any significance to motor windings thickness?

Postby arkmundi » Wed Jul 01, 2015 2:11 pm

The amount of copper in the windings paired to magnets is what matters and not the wire gauge per-se. Its hard to tell from pictures, or even manufacturer specs. The best way to tell, if you're comparing two motors, is to get them both and do some field testing. Then shipping the one you don't want back for a full refund. You'd be out shipping costs. Crank the motors to maximum rpm at a constant maximum amperage with a thermister and measure the temperature gradient. Direct correlation to the mass of the copper.
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Re: is there any significance to motor windings thickness?

Postby John in CR » Wed Jul 01, 2015 8:15 pm

Significantly more copper will fit on both of those motors, so they're both crap AFAIC. There's a hole in the understanding at a number of manufacturers of similar motors. Our use isn't some home or industrial appliance where the design calls only for durability at given torque and rpm. Heat is our limitation, and any motor that doesn't fit as much copper as possible on the stator teeth will make more heat than one with proper copper fill, so what you want to see is maximum copper fill. Then it's just a matter of choosing the right one wound for the voltage and rpm you need.
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Re: is there any significance to motor windings thickness?

Postby teslanv » Wed Jul 01, 2015 9:04 pm

And the next inevitable question is what voltage and rpm should I use? :wink:
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Re: is there any significance to motor windings thickness?

Postby Hugh-Jassman » Thu Jul 02, 2015 1:37 pm

I need to see a performance chart of the eco speed at least.
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Re: is there any significance to motor windings thickness?

Postby newbiebiker » Fri Jul 03, 2015 12:53 am

i read somewhere not sure whether it is true or not , that is "if we used silver means, only 2/3 of the winding length is enough compared to copper" same torque and all, but less weight due to silver winding.
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Re: is there any significance to motor windings thickness?

Postby Miles » Fri Jul 03, 2015 2:02 am

newbiebiker wrote:i read somewhere not sure whether it is true or not , that is "if we used silver means, only 2/3 of the winding length is enough compared to copper" same torque and all, but less weight due to silver winding.
Miles wrote:
zener wrote:You can take silver wire than all copper losses are gone. :D
But the Silver losses are nothing to write home about, either... :mrgreen:


Thread from 2009:
http://www.endless-sphere.com/forums/vi ... 30&t=13544
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Re: is there any significance to motor windings thickness?

Postby John in CR » Fri Jul 03, 2015 7:12 pm

Silver vs copper is interesting, but silver wire will mostly get sold as something better to the high end audio crowd. Silver has an advantage in terms of resistance at 20°C, but it's density is greater than copper by a wider margin, so a silver wired motor would have to be heavier. Also, depending on the source of info and I tend to believe what's on EngineeringToolbox.com, the resistance of silver increases significantly faster with temperature than copper.

It appears that the break even point is somewhere around an operating temp of 90-100°C with higher temps tilting the resistance scale in favor of copper. That's before considering cost and greater issues working with silver wire.
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Re: is there any significance to motor windings thickness?

Postby speedmd » Fri Jul 03, 2015 10:00 pm

Silver is a better conductor than copper if pure and dead soft. When hard / drawn it is virtually equal. (page 503 of the link) 100 for silver vs 99.95 for copper https://books.google.com/books?id=BawtAAAAYAAJ&pg=PA503&lpg=PA503&dq=metals+electrical+conductivity+at+100c&source=bl&ots=Aij7-D0oai&sig=c6DuykxWvR_idQ-tcm_X8MKxZi0&hl=en&sa=X&ei=b0aXVf_sCoG7-AHmz5jgCw&ved=0CDYQ6AEwBA#v=onepage&q=metals%20electrical%20conductivity%20at%20100c&f=false

It also is better than copper as the temperature rises loosing less conductivity, but has many disadvantages also. In high voltage and high humidity silver migrates and builds conductive paths where you do not want them over time. Not a good tradeoff.
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