Leafmotor project

John in CR said:

Slow wind motors are fine for those who are positive they never go faster, however, they are easier to push to heat failure on long hills because even relatively low power controllers can push enough current through their far higher resistance windings.

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OK, back to the simulator. Hm, it looks to me like at any reasonable speed, that 2707 goes farther before it overheats, than the 2705. Also at unreasonable speeds, and at unreasonable grades. At 8% full throttle, 52V x 20A controller, the 2707 goes 5 miles, the 2705 3 miles. At 5% grade, they 2705 runs a little hotter and slower. At 20A, to see the benefit from the 2705 even on level ground, I have to switch to the "full recumbent" setting. At 35A I can get 2705 speed on the flats on an upright, and they can run pretty ridiculous grades at very comparable outcomes, but the 2707 always pulls a little ahead on the hills.

I can't find the setting where "they are easier to push to heat failure on long hills", so I can't say for sure what that's about, but I hope you aren't playing the same game he does with his "Plus you can cruise at full throttle at a speed that makes sense for a bicycle" (I mean, I don't know, maybe someone craves the setup that will routinely be operated at full throttle, but as the simulator itself puts it, "that is not usually representative of how people ride an ebike.")

Isn't it really about what size of wheel? If you have a 20 inch wheel, then you'd certainly want the fast wiring, while the higher count is for a 26" or 700c wheel?

Assume that I will use the 48V, 35A controller that is offered along with the motor. Which makes more torque if I do that? Slow wind or fast wind?

donn said:

[apples and oranges comparisons not worthy of quoting]

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Balmorhea said:

[apples and oranges comparisons not worthy of quoting]

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Guys, you are wasting everyone's time by using apples and oranges comparisons to support your erroneous conclusions, and it is a disservice to the membership of the forum to propagate misleading information, especially regarding the topic of different windings of motors since it is already so broadly misunderstood and that misunderstanding is reinforced by sellers misleading claims in advertising. Ten's of thousands of dollars have already been pissed away by members following the mythological idea of slow wind motors being better at hill climbing and making more torque resulting in burned up motors, since slow wind motor versions are more easily pushed into heat failure.

John in CR said:

since slow wind motor versions are more easily pushed into heat failure.

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We should be able to see this in the simulator, with the right parameters. Various hub motors represented there in multiple windings.

When I try it, the slow winds look good on a 26" wheel. That makes sense to me - I don't know about their supposed "far higher resistance", but there's an obvious analogy here to mechanical advantage. I don't think the difference is significant enough to be super compelling to someone who really craves the fast wind's extra couple of miles per hour at the top end - so I'm not on any crusade against fast winds - but it convinces me that fast winds really belong on 20" wheels.

So I leave it in your hands. It's yours to substantiate, with the necessary simulator parameters or whatever you think it is an acceptable substitute.

John in CR said:

Guys, you are wasting everyone's time by using apples and oranges comparisons to support your erroneous conclusions,

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No, that's what you're doing when you prescribe a different controller and battery for every different application, along with wheel sizes no normal adult bike was designed to use.

donn said:

John in CR said:

since slow wind motor versions are more easily pushed into heat failure.

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We should be able to see this in the simulator, with the right parameters. Various hub motors represented there in multiple windings.

When I try it, the slow winds look good on a 26" wheel. That makes sense to me - I don't know about their supposed "far higher resistance", but there's an obvious analogy here to mechanical advantage. I don't think the difference is significant enough to be super compelling to someone who really craves the fast wind's extra couple of miles per hour at the top end - so I'm not on any crusade against fast winds - but it convinces me that fast winds really belong on 20" wheels.

So I leave it in your hands. It's yours to substantiate, with the necessary simulator parameters or whatever you think it is an acceptable substitute.

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Using the wording "mechanical advantage" means you think that changing winding is like changing gearing, which is factually incorrect. Different winds make the same torque, same efficiency, same power. They just require difference combinations of voltage and current for the same power input for the identical results. If you use an unequal input like Balmorhea does to make his claims of more torque with his slow wind motor, then he is making more heat to make that extra torque. The EXACT same results (torque, efficiency, etc) he gets with his slow wind motor are easily achieved with a fast wind motor with the right combination of lower voltage and higher current for the same power input.

Wheel diameter is the only means of changing the gearing for a hubbie, and running the smallest wheel you can live with is always best. Large diameter wheels like a 700c aren't even offered on the biggest most powerful hubmotors because it is too steep a gearing for the motor to function correctly. The same is true for ebike hubmotors and simulations readily demonstrate how much more efficiently hubmotors run in a smaller wheel because they are not stressed by gearing too steep.

Balmorhea said:

John in CR said:

Guys, you are wasting everyone's time by using apples and oranges comparisons to support your erroneous conclusions,

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No, that's what you're doing when you prescribe a different controller and battery for every different application, along with wheel sizes no normal adult bike was designed to use.

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Point to an example of a single time I did any of those things.

Assume that I will use the 48V, 35A controller that is offered along with the motor. Which makes more torque if I do that? Slow wind or fast wind?

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You still haven’t answered my question.

This is apples to apples comparison.

John in CR said:

The EXACT same results (torque, efficiency, etc) he gets with his slow wind motor are easily achieved with a fast wind motor with the right combination of lower voltage and higher current for the same power input.

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I'd give you "close" - so far, the simulator comparisons I've seen have been close. Not so sure about "exact", but who knows, since we're already "close", this isn't hard to believe. It's kind of a long way from showing the thousands of dollars' worth of burned up motors you were talking about.

I agree that a smaller wheel is more robust with a hub motor, particularly a direct drive like mine. But of course since our bicycles aren't typically very flexible about major changes in wheel diameter, many of us use a hub motor on a larger diameter wheel, anyway. Since this is as you say the major factor, if there are thousands of dollars worth of burned up motors, that's why, right? Bicycles have large diameter wheels; they're hard on hub motors, but that's life. Given a 26" rear wheel, doesn't it make sense, to use a slow wind on it? For me, the simulator says "yes (unless you want those extra couple mph.)" Can you set it up so the simulator says no, you're better off with a fast wind on the 26" wheel?

Don't want to get in to the fast/slow debate. My leafmotor maybe the lowest Kv leafmotor among the ES members it's a 7T, 6.56 Kv. There is no problem with this motor it fits my needs at this time. It will keep your battery usage down not because it's better. More like a governor and with governor's your rpm's need to drop before it builds torque/hp. My trike is setup to do 28mph/46kph, it will do 53kph but the first little hill it will slowdown to 28mph before building any torque. This is not really ideal for for riding at 28mph. I spend most of my time between 15-20mph but my setup is ideal for this. Most of torque gain from a lower Kv is below 5mph/8kph, do not spend any time riding in this range.
Disclaimer: The winding of a motor does not allow for it to make more torque than the design allows.

Have been reading a lot on here, playing with motor simulator and listening to Justin. What is sinking in is everyone is staring at efficiency numbers but not watts per km/mi. All motors have a sweet spot, where they make the most torque/watt. Does not matter what voltage, Kv, amps. "John in CR" knows about this it's around 50-60% of the max rpm. My motors sweet spot is where I peddle the most. Would like it closer to where my motor does all the work and below my set speed limit. Going to swap out my 7T, 6.56 for a 5T, 10.56 Kv, which would get me up to 40mph/66kph but not interested in that. Want 60% between 20-28mph, so I will try that for a year. I average 9w/km, They do vary from time to time 4w-20w/km. I should see my average go up or down.

ZeroEm said:

Have been reading a lot on here, playing with motor simulator and listening to Justin. What is sinking in is everyone is staring at efficiency numbers but not watts per km/mi. All motors have a sweet spot, where they make the most torque/watt. Does not matter what voltage, Kv, amps. "John in CR" knows about this it's around 50-60% of the max rpm.

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Interesting ... when I look for that on the simulator, it looks to me like "wheel torque" vs "motor power" just keeps going down, as the speed goes up. Torque vs. battery power, same thing. That isn't graphed, have to do the arithmetic manually so I only sampled a few different throttle settings. Wonder what I'm missing?

Same with Wh/mile - even at very slow speed when the motor is running at 50% efficiency, you'll go farther on a charge, I expect partly due to lower wind resistance.

markz said:

https://endless-sphere.com/forums/viewtopic.php?f=2&t=24593&p=381600&hilit=myth#p381600

https://endless-sphere.com/forums/search.php?keywords=myth&terms=all&author=justin_le&sc=1&sf=all&sr=posts&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

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https://endless-sphere.com/forums/viewtopic.php?f=2&t=14482&p=218275&hilit=myth#p218275
justin_le » Mon Dec 07, 2009 - "The myth that more turns = more torque is deeply pervasive in this industry."

"No, it's not an aberration. More turns of thinner gauge copper or fewer turns of thicker copper has no effect on the torque output of a motor. All that matters is the net copper fill factor, and in the case of a 9x7 or a 6x10 winding, there is actually ever so slightly more copper in the faster 9x7 hub (61 strands) compared to your 60 strands in a 6x10. "

"and that the torque difference that is there has to do with controller losses and not the motors per se. A higher turn motor SHOULD be sold as a 'higher voltage' hub, not a 'higher torque' hub. "

https://endless-sphere.com/forums/viewtopic.php?f=2&t=7891&p=980986&hilit=myth#p980986
"and they are both fundamentally capable of exactly the same speeds and torques, it's just that the 3540 winding does it at a lower voltage and higher current than the 3525. "

When we can buy a controller that supports any voltage with any amount of current you want, and a battery whose voltage can be dialed up or down without efficiency losses or current limits, and we have superconducting phase wires into the hub motor, then a low turn count motor can work just as well as a high turn count motor at bicycle speeds. We’re not there yet.

In the world of today, 36-52V batteries and controllers with sub-50A ratings are what we’ve got that are both easy to find and inexpensive to buy. Together, they are almost always more expensive than the motor, and a more significant limitation on system performance.

Again, this is the Leaf motor we’re discussing, and Leaf offers any winding you request at no extra charge. So why not choose the winding to match your use case, instead of choosing a controller that costs a lot more per watt, and a battery that costs a lot more per watt-hour (both of which may complicate later parts replacement)?

by donn » Sep 29 2020 2:36pm

ZeroEm wrote: ↑Sep 29 2020 1:45pm
Have been reading a lot on here, playing with motor simulator and listening to Justin. What is sinking in is everyone is staring at efficiency numbers but not watts per km/mi. All motors have a sweet spot, where they make the most torque/watt. Does not matter what voltage, Kv, amps. "John in CR" knows about this it's around 50-60% of the max rpm.

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Interesting ... when I look for that on the simulator, it looks to me like "wheel torque" vs "motor power" just keeps going down, as the speed goes up. Torque vs. battery power, same thing. That isn't graphed, have to do the arithmetic manually so I only sampled a few different throttle settings. Wonder what I'm missing?

Same with Wh/mile - even at very slow speed when the motor is running at 50% efficiency, you'll go farther on a charge, I expect partly due to lower wind resistance.

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Disclaimer: This is close to my setup, the motor's Kv is 6.33. 6.53 Kv matches the performance better at 72V, don't ride around at 72V. This setup has good low speed torque and is a combination of low Kv and higher voltage at the expense of higher end power.

My speed limit is set at 46kph. Looking at the chart torque and motor power start dropping off between 20-25mph. This is where my power drops off also due to health. I think the best watts/torque is around 24kph/15mph but I also can peddle hard at 24kph and the wind resistance is very low at that speed. The motor is set to max out at 8kph/5mph higher than my speed limit. As you can see the motor power is nose diving.

I think the setup would be better if I did not have my motor max out so close to my max speed and get better response to inclines. Don't need as much torque on the low end as my peddling is in there. I don't ride up hills at 0-15 mph, ride up hills 15-25mph at them speeds and the size of the hills here that is less than 2 mins.

It takes less and less torque to move the e-bike at a speed (set by the throttle) then at a stand still, thats why at a stand still the torque is highest because it requires high torque to get moving at speed. Once you are moving it takes less torque.

donn said:

Given a 26" rear wheel, doesn't it make sense, to use a slow wind on it?

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No, winding doesn't matter. If you're only coming close on the sims, then you're still not quite apples and apples. The real world differences are minuscule and related to things like tiny differences in end turn losses. What you should look for is the winding that has the best copper fill, because that's the most efficient at making torque, which in the case of the Leaf are the 6 and 3 turn if I remember correctly. I personally would take the 3 because for low speeds I could just run a 24V or 36V pack (half the parts in the bms, so half the potential points of failure), and the 3 turn could be used for a higher performance build, and you can still have the lower power (but equal torque and efficiency) at slower speeds simply by using less throttle.

It sounds like you still haven't accepted the simple fact that torque and power limits and efficiency of a motor aren't determined by the windings. They are set by the design, iron structure, and magnetic circuit. How many turns of copper (which varies inversely with the length and thickness of that copper) only determines the combination of voltage and current for identical results for the different winds assuming the factory fit the same total amount of copper on the stator teeth). I live in a mountainous region, and I push much heavier loads than most, and I just got lucky that an early factory purchase of hubmotors was 2 turn hubbies with a 40mm stack of lams on the stator (pretty comparable to the Leaf). I also bought some other more typical wind hubmotors at the time, and that was back before high power controllers were even available. Even before I understood this winding thing, it was forced upon me, because I wasn't suffering failures like the rest of the guys here, despite steep mountain climbs and heavier loads.

Regarding wheel size, if you're fully into electrics as basic transportation then it behooves you to learn how to build your own bikes to accommodate a smaller wheel, because that lower gearing is a huge advantage. Your motor runs more efficiently and you have more space for batteries. Then you can split the difference and use some of the gain for more performance and still get more range out of your batteries.

John in CR said:

Regarding wheel size, if you're fully into electrics as basic transportation then it behooves you to learn how to build your own bikes to accommodate a smaller wheel, because that lower gearing is a huge advantage.

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But not if you're a bicyclist. The machine is there to serve you, not you to serve it.

ZeroEm said:

My speed limit is set at 46kph. Looking at the chart torque and motor power start dropping off between 20-25mph. This is where my power drops off also due to health. I think the best watts/torque is around 24kph/15mph but I also can peddle hard at 24kph and the wind resistance is very low at that speed. The motor is set to max out at 8kph/5mph higher than my speed limit. As you can see the motor power is nose diving.

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There is that peak, for sure. The thing is, at that point on the chart, the power considerably exceeds the load, the black line, so you're accelerating, at about 4 kph/s. If you let up on the throttle at this point and hold it at 37kph, you'll get pretty fair mileage - and you'd very nearly same mileage at that speed, with the standard 5T Leaf. If you throttle down more, you'll get even better mileage. I can't see any optimum speed here.

As long as you hold it under 30mph, you'd get so near the same result from your winding and the standard 5T, that the difference is not relevant to the real world. You're getting maybe 25% more acceleration power off the line with yours, in compensation for the extra few miles per hour you miss out on at the top. (According to the simulator.) In neither case will your motor burn up, hair fall out or whatever other claims people have been making.

John in CR said:

It sounds like you still haven't accepted the simple fact that torque and power limits and efficiency of a motor aren't determined by the windings. ... Even before I understood this winding thing, it was forced upon me, because I wasn't suffering failures like the rest of the guys here, despite steep mountain climbs and heavier loads.

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Which failures you've been telling us are because of slow winds, because of their higher resistance.

This resistance problem was apparently unknown to the people who set up the motor simulator profiles, because it doesn't show up there?

And the small torque and efficiency advantages with the slow wind motor profiles, also in error because of subtleties that were lost on the people who set up the simulator? Or would you be willing to concede that for normal bicycle speeds and conditions on a 26" wheel, the slow wind is just a teeny tiny bit more efficient and powerful?

donn said:

Or would you be willing to concede that for normal bicycle speeds and conditions on a 26" wheel, the slow wind is just a teeny tiny bit more efficient and powerful?

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I'm guessing no.

You left out stronger off the line, and better range.

Balmorhea said:

You left out stronger off the line, and better range.

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Sure ... but - not to put too fine a point on it, but I'm not claiming these are really significant advantages in the larger scheme of things. Enough to tip me towards a slower wind, but not enough to make me think I'd be able to tell the difference.

donn said:

Which failures you've been telling us are because of slow winds, because of their higher resistance.

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Almost every burned up motor on the forum.

donn said:

This resistance problem was apparently unknown to the people who set up the motor simulator profiles, because it doesn't show up there? Like I said early, people burn them up because they're easier to burn up due to the lower current required to do so.

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Of course it does. It's motor basics and Justin is a true ebike scientist set all that stuff up properly. It's quite simple. More turns means a thinner and longer bundle of magnet wire to form each phase of the windings. The resistance varies inversely with the square of Kv. ie Half the Kv means half as thick copper that is twice as long for 4 times the resistance. Heat in the copper happens at the square of current, which is what puts all of the different windings of a motor exactly equal (assuming of course that the same amount of copper was fit around the stator teeth.

donn said:

And the small torque and efficiency advantages with the slow wind motor profiles, also in error because of subtleties that were lost on the people who set up the simulator? Or would you be willing to concede that for normal bicycle speeds and conditions on a 26" wheel, the slow wind is just a teeny tiny bit more efficient and powerful?

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There absolutely without question is no torque and/or efficiency advantage of a slow wind motor. This is a simple fact that you and everyone else on the forum who has been sold the idea of a "high torque" model of a motor should accept. This topic was hashed out on the forum in the monster "Myth" thread years ago, where the top forum members who really know this stuff from the pure physics standpoint gathered together to attempt to put the matter to rest once and for all. It pokes it's ugly head up continuously ever since, and I'm left as the lone stalwart with the patience to fight ignorance perpetuated by vendors and forum members who due to their personal experience via apples and oranges real world comparisons reached the wrong conclusions. Unfortunately frequent regular posters like SpinningMagnets and Dogman et al claim ignorance about how our motors really work due to pure laziness since the basic concept is quite simple, so they do nothing to help stamp out this cancer of ignorance that has people thinking that slow wind motors are more efficient or produce more torque in any comparable conditions than a faster wind motor.

Think about this for a second. Hear I was 10years ago running motors with a Kv of just over 16rpm/volt pushing a 400lb+ load in mountainous terrain and still had the fastest ebike on the forum running less than the OP of this thread plans with a 40-60A controller. This was all with a motor pretty comparable to the Leaf motor. If what you''ve been thinking is true how were my real world results possible? FWIW that was up until 9 years ago as better controllers started to become available, and I stretched what I learned to higher power using higher Kv and higher efficiency hubmotors. I still ride in mountainous terrain, and ride at about the same speeds pushing heavier loads than ever, but now it's on ebikes with a top speed of over 100mph. On top of that, despite running higher rolling resistance motorcycle tires on my ebikes and pushing a heavier load, with the same battery pack I could ride side by side (no pedal input) with Balmorhea at whatever speed he chooses and get greater range out of that pack...proving that the things I say are true.

by donn » Sep 29 2020 11:52pm

ZeroEm wrote: ↑Sep 29 2020 9:27pm
My speed limit is set at 46kph. Looking at the chart torque and motor power start dropping off between 20-25mph. This is where my power drops off also due to health. I think the best watts/torque is around 24kph/15mph but I also can peddle hard at 24kph and the wind resistance is very low at that speed. The motor is set to max out at 8kph/5mph higher than my speed limit. As you can see the motor power is nose diving.

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There is that peak, for sure. The thing is, at that point on the chart, the power considerably exceeds the load, the black line, so you're accelerating, at about 4 kph/s. If you let up on the throttle at this point and hold it at 37kph, you'll get pretty fair mileage - and you'd very nearly same mileage at that speed, with the standard 5T Leaf. If you throttle down more, you'll get even better mileage. I can't see any optimum speed here.

As long as you hold it under 30mph, you'd get so near the same result from your winding and the standard 5T, that the difference is not relevant to the real world. You're getting maybe 25% more acceleration power off the line with yours, in compensation for the extra few miles per hour you miss out on at the top. (According to the simulator.) In neither case will your motor burn up, hair fall out or whatever other claims people have been making.

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Yes, i'm hopping for a lower watt/km with my riding style. When I built this trike it was to help me up hills. I'm heavy, have some steep hills but not long. Did not know what to expect, so I read about motors over heating on hills and how low Kv motors pull the lower end better with lower AMP's, knew I could get same low end if high amps was used. Did not want to buy a high amp controller and run bigger phase wires out my motor, limit my amps at 36amps (continuous rating of one battery). wanted to tap some of the potential in this motor, lowered the Kv and raised the voltage and stayed below 40 amps.

Don't want to enter the debate on motors between "Balmorhea" and "John in CR". They are both right in my view. Depends on how you want to ride. If you need higher speeds and more power or if you want to keep your bike a bike at bike speeds. I want some of both. I need a couple more builds one more in the Bike area and the other more extreme.

John in CR said:

...proving that the things I say are true.

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Maybe that proves it to you. What would prove it to me, would be if I could see it in the motor simulator.

You say it's there. Tell us where. There are several motors to choose from with multiple winding options - I've been using 9C+, but I don't care. Whatever standard issue controller and battery, grade incline, etc., suit yourself - but of course let's stick to the 26" wheel.

What I've seen so tells me that the slower winds seem slightly more optimal for a 26" wheel. I have to assume that's more relevant to a common 26" setup, and you're talking about something else that isn't a concern for the typical motor shopper.

donn said:

John in CR said:

...proving that the things I say are true.

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Maybe that proves it to you. What would prove it to me, would be if I could see it in the motor simulator.

You say it's there. Tell us where. There are several motors to choose from with multiple winding options - I've been using 9C+, but I don't care. Whatever standard issue controller and battery, grade incline, etc., suit yourself - but of course let's stick to the 26" wheel.

What I've seen so tells me that the slower winds seem slightly more optimal for a 26" wheel. I have to assume that's more relevant to a common 26" setup, and you're talking about something else that isn't a concern for the typical motor shopper.

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Here you go...an apples to apples comparison of a 7Kv and 14Kv motors on a 10% grade hill. IDENTICAL results just like I said.