is there any significance to motor windings thickness?

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emaayan   100 kW

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is there any significance to motor windings thickness?

Post by emaayan » Oct 15 2013 4:01am

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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Miles   100 GW

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Re: is there any significance to motor windings thickness?

Post by Miles » Oct 15 2013 4:03am

No, you can't tell anything from the winding gauge on its own.

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Hugh-Jassman   1 kW

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Re: is there any significance to motor windings thickness?

Post by Hugh-Jassman » Jul 01 2015 1:14pm

would the Eco-speed motor handle less amperage at a low voltage? or the other way around?

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Miles   100 GW

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Re: is there any significance to motor windings thickness?

Post by Miles » Jul 01 2015 1:22pm

It would require a lower level of amps but a higher level of volts, for the equivalent output

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arkmundi   1 GW

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Re: is there any significance to motor windings thickness?

Post by arkmundi » Jul 01 2015 2:11pm

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.

John in CR   100 GW

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Re: is there any significance to motor windings thickness?

Post by John in CR » Jul 01 2015 8:15pm

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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teslanv   100 MW

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Re: is there any significance to motor windings thickness?

Post by teslanv » Jul 01 2015 9:04pm

And the next inevitable question is what voltage and rpm should I use? :wink:
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Hugh-Jassman   1 kW

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Re: is there any significance to motor windings thickness?

Post by Hugh-Jassman » Jul 02 2015 1:37pm

I need to see a performance chart of the eco speed at least.

newbiebiker   100 mW

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Re: is there any significance to motor windings thickness?

Post by newbiebiker » Jul 03 2015 12:53am

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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Miles   100 GW

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Re: is there any significance to motor windings thickness?

Post by Miles » Jul 03 2015 2:02am

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

John in CR   100 GW

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Re: is there any significance to motor windings thickness?

Post by John in CR » Jul 03 2015 7:12pm

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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speedmd   100 MW

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Re: is there any significance to motor windings thickness?

Post by speedmd » Jul 03 2015 10:00pm

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=BawtA ... 0c&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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