Leafmotor project

John in CR said:

Here you go...an apples to apples comparison

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Your still haven't answered my question.

Balmorhea said:

Assume that I 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.

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What could be more of a fair, equal comparison than the same controller, same battery, and same motor with the only difference being winding?

Will you answer this simple question, please?

John in CR said:

donn said:

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

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Fine, they can be made to equal out with controllers with exotic parameters - 24V x 70A? Since the difference is not all that large with normal controllers, this is no great surprise.

If this is all you've got, then apparently I was right - you're talking about something different, and those of us who use ordinary motors and controllers off the shelf on a 26" wheel, can expect the slightly better results the simulator shows for a slower wind. And we don't have to worry about this choice causing motor overheating, because to the small extent it makes any difference, that's really one of the ways it's better.

Balmorhea said:

What could be more of a fair, equal comparison than the same controller, same battery, and same motor with the only difference being winding?

Will you answer this simple question, please?

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It's wrong because a controller appropriate for a slow wind motor isn't appropriate for a fast wind motor and vice versa, but that's exactly what people trying to get more from their ebike tend to do to slow wind motors and they burn them up. Just for grins let's see what happens. Note that I put both motors at 100°C, though due to its much lower efficiency on the climb at less than half the speed the slow wind motor would surely burn up by the halfway point of the length of this 10% grade hill that the fast wind motor struggles to crest.

Note that at almost every throttle position, the fast wind motor has more torque, higher efficiency, and more than double the speed on this climb. At the point of equilibrium with the load of the hill at 100%, the fast wind motor is at 69% efficiency vs 55% for the crap wind and is climbing it at a respectable 27kph vs a measly 11kph. Also note that despite going more than twice as fast the fast wind motor still gets more range from the pack in those conditions. The mistaken but broadly thought idea that slow wind motors are better on hills is obviously so very wrong.

John in CR said:

Balmorhea said:

What could be more of a fair, equal comparison than the same controller, same battery, and same motor with the only difference being winding?

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It's wrong because a controller appropriate for a slow wind motor isn't appropriate for a fast wind motor and vice versa,

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It’s the one that comes with the motor. Chosen to be suitable by the motor manufacturer. It isn’t 70A, it’s 35A. It isn’t 24V, it’s 48V.

You still didn’t answer my simple question.

Balmorhea said:

John in CR said:

Balmorhea said:

What could be more of a fair, equal comparison than the same controller, same battery, and same motor with the only difference being winding?

Click to expand...

It's wrong because a controller appropriate for a slow wind motor isn't appropriate for a fast wind motor and vice versa,

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It’s the one that comes with the motor. Chosen to be suitable by the motor manufacturer. It isn’t 70A, it’s 35A. It isn’t 24V, it’s 48V.

You still didn’t answer my simple question.

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The same thing happens with the 52V battery and 60A controller the OP talked about, though not as pronounced a difference, and the crap wind motor doesn't get close to the performance the OP desires, but the fast wind motor gets there in a 26", despite it still being too big a wheel for the motor to run at its best because the over-gearing puts it under stress.

I'm done answering your ignorant questions because you simply don't want to learn anything, but spewing false information, because most are here to learn and no one with any real sense wants to knowingly share inaccurate info. Of course what should we expect from someone who not long ago was one of those cycling elitists who thumbed their noses at us calling ebikers cheaters and worse, who only got into ebikes to make money once they gained broader acceptance. On one hand you'll help a cyclist spend thousands on a new pedal bike they don't need to save 100-200 grams that doesn't make a hill of beans difference, but heaven forbid someone should recommend a better controller (the brain of the ebike system) that makes a real difference and can grow with them over some cheap Chinese crap with no flexibility.

John in CR said:

Balmorhea said:

John in CR said:

Balmorhea said:

What could be more of a fair, equal comparison than the same controller, same battery, and same motor with the only difference being winding?

Click to expand...

It's wrong because a controller appropriate for a slow wind motor isn't appropriate for a fast wind motor and vice versa,

Click to expand...

It’s the one that comes with the motor. Chosen to be suitable by the motor manufacturer. It isn’t 70A, it’s 35A. It isn’t 24V, it’s 48V.

You still didn’t answer my simple question.

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The same thing happens with the 52V battery and 60A controller the OP talked about, though not as pronounced a difference, and the crap wind motor doesn't get close to the performance the OP desires, but the fast wind motor gets there in a 26",

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That wasn’t the question. Can you please read it and try again? It’s a really simple question.

Assume that I 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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Slow motor has way more torque ------> if you dont compensate by changing a single parameter, but thats not really a proper comparison.

Once you change the parameter to compensate the slower motor has very slight advantage.

Remember that the more amps you draw, the more losses you will have.

Knowing what motor you plan to use and whats it KV.

Its all about losses.

markz said:

Slow motor has way more torque ------> if you dont compensate by changing a single parameter, but thats not really a proper comparison.

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Leaf 1500W kits come with a 48V, 35A KT controller. Just the one kind. But you can get any winding you want by request, at no extra charge.

To me, it sounds like they know what they're doing.

When John recommends a 24V controller with 140 phase amps to do the job that the default Leaf kit controller does, it sounds to me like he doesn't know what he's doing, at least in terms of results per cost and effort.

The last few paragraphs explains the myth well.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=64907&p=984783&hilit=motor+torque+myth#p984783

ElectricBikeReview.com video of the tour of Grintechs old store.
1V vs 100V - Start at 7 minute mark in the video - https://www.youtube.com/watch?v=IxB2j-egWcQ&pbjreload=101

markz said:

The last few paragraphs explains the myth well.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=64907&p=984783&hilit=motor+torque+myth#p984783

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justin_le said:

Now replace the controller on the Faster 3540 winding with one that has fatter gauge wire so that it's only 10mOhm of resistance, and you can see that the torque difference between the two systems almost completely vanishes

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Well, there you go. What they're talking about appears to be a technicality, a distinction that's irrelevant to someone who will buy a motor and a controller off the shelf and won't be offered a choice of controller wire gauge. I don't care if what I'm seeing on the simulator is strictly speaking an effect of the controller or the motor. The effect is consistent, given the two winds and any off the shelf controller available in the simulation, so ... whatever. I guess we can conclude from this that controllers are routinely not built to make the best of a fast wind. Too bad, but it is what it is. On a 26" wheel, with any off the shelf controller, a slow wind means very slightly better performance under load, off the line, etc. - pulls harder, stays cooler. If not, then the simulator has a problem. I think under these circumstances, there might be some confusion about where the "myth" is.

markz said:

Slow motor has way more torque ------> if you dont compensate by changing a single parameter, but thats not really a proper comparison.

Once you change the parameter to compensate the slower motor has very slight advantage...

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Mark,
Actually that isn't true, because the controllers behave very differently pushing phase current into the 2 different loads with very different sets of resistance, inductance, and BEMF curve. The crap wind motor has only a minor torque advantage that disappears very quickly and reverses to be in favor of the fast wind motor through the mid and upper range rpm. I have some very high efficiency 2 speed motors that do a series/parallel switching inside the motor which doubles the Kv switching from low to high, so I've seen the effect first hand with same controller and battery with Kv changing by double at the flip of a switch. Low had only a small advantage in torque at low speed, and those motors were heat failure prone in low, so I just solder copper over the high/low switch contacts to lock them in high as well as get rid of the extra resistance of the switching mechanism making it even more efficient.

I don't know how that works exactly, so maybe my new more advanced controllers may be able to take advantage of the low speed torque advantage of low Kv winds on paper. My old cheapie Chinese controllers that limit current from the battery side certainly couldn't, and LiveForPhysics post below from the myth thread may shed some light in this regard, but the simulator doesn't accurately model the low speed torque difference, at least for the few different controllers I tried on that motor.

liveforphysics said:

teslanv said:

Coming back to the Myth a little here:

Is it fair to say that for a given motor design (And negating any controller inefficiencies), if you were to compare a 16X4-Turn motor to a 8X8-turn motor, could you accurately say that:

For a given battery voltage at 100% Throttle, the 16X4-Turn motor will spin exactly twice as fast as the 8X8-Turn motor and for a given battery and phase current profile (amperage) the 8X8-turn motor will produce twice the torque as the 16X4-Turn motor.

Or to say this statement a different way:

It takes twice as much voltage for an 8X8-turn motor to spin at the same RPM as a 16X4-turn motor, and it takes twice as much current for the 16X4-turn motor to produce the same torque as the 8X8-turn motor.

I am not trying to propagate any more myth here, just trying to confirm that what I understand about the relationship between a motor's winding, and Speed and torque are accurate.

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Anytime the motors with differing Kv in your example are at the same RPM getting the same input power, they will be making exactly the same amount of torque output, as well as the same amount of heat produced to make that torque as well as identical efficiency and battery current etc.

In your example, the motor with half the turns gets twice the RPM range of the other of course.

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markz said:

Remember that the more amps you draw, the more losses you will have...

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This part is partially true. Heat losses certainly go up with everything that's the same before the motor. Once you get to the 2 different motor windings, the increased current requirements to properly drive a high speed wind motor don't increase losses. You can increase current by the same % as the increase in Kv of the same motor and incur the same losses.
that Kv increases from the slow wind to the fast wind.