How practical is 72v (or 60v) for a street legal direct drive set-up meant for climbing and sub 28 mph speed?

[donn]

Yes! It certainly doesn't make sense to use the existing real life controllers that are modeled in the motor simulator, because what would that prove!?

 

[serious_sam]

All of the windings climb the same, have the same torque, same efficiency, and can run in the same size wheel. It only takes a different combination of voltage and current for the same power input to get the same torque, speed, and power out at the same efficiency. The only time a different winding needs to come into play is if you're already locked into a specific voltage...

...or current.

What you say is true, so I always find it hypocritical that you say that, but then you always go on to say that a faster wind is better.

The reality is, there are usually a larger range of windings available for a specific motor (usually at no cost difference), but controllers are limited and usually have large cost differences for increases in current handling, but usually run the same voltage limit within a brand (e.g. Nucular 6F vs 12F vs 24F).

So what you should really be suggesting, is choose the appropriate winding for the chosen speed and acceleration, according to the preferred controller. And then size a battery according to those performance targets.

None of this faster winds are better bullshit. It's different horses for different courses.

 

[MadRhino]

Well, you can have a cheap controller feeding high power, as well as an expansive one that feeds low power. Preferred controller is a matter of software and functions. If you prefer one that is very expansive, it is not for its power or at least, it shouldn’t be.

I don’t select a motor kv for a controller. It is the wheel size that is the most important factor of selection, because very fast motors are not happy in a large wheel.

 

[dogman dan]

When I got the most out of a slow motor, it was by NOT giving it more power than it could handle. Id done the too much power, melt a motor every spring when it got warm thing long enough. Yeah, it worked in winter, but I kept melting the halls on a motor every spring. It was only ok in winter, and when I did not care how much watt hours I wasted.

All I wanted from that slow motor on the cargo bike was to enforce going slower.

But my goal was very specific, and NOT the goal of the OP here. My goal was to go the farthest possible on 48v, loaded to up to 400 pounds, using a 1000w controller. To reach this goal, you have to go slow. The main thing that got me the 400 pound load possible on 1000w was the 20" rear wheel. And I achieved going slow by using a winding unable to go faster than 18 mph on that voltage in a 20" wheel.

A faster wind would have worked just as good!!! But I get throttle creep and ride too fast at some point in an 80 mile ride, so the winding limited my speed absolutely. I was using a controller incompatible with a DP CA, so it got a bit harder to limit that way. In this case, the build was to see what the max range and max load I could squeeze from a stock E bike kit was. So I had the EBK 10 turn motor, and the 20" rim, and stock controller and display.

The OP wants to limit speed to 28 mph. Thats perfect for typical rpm DD motors on 48-52v. So why a slower motor?

Only if you are already locked in on 72v, meaning you spent your wad on one already and don't have more to spend.

Whatever motor you choose, dont overpower it. Don't think you will get more power from a slow wind at 72v than a fast wind at 48v, if the wattage is below the limits of the motor. Oh yeah, you can overpower any wind motor, briefly. It can be fun to watch the flames shoot out the cooling holes in the motor.

 

[ebike4healthandfitness]

The difference need to be expressed as a percentage. If a slow winding does 30 mph at 72v it will have the same % speed drop at lvc as a fast winding doing the same top speed at 48v, simply because the fast winding will drop more rpm per volt, proportionally.

Learn something everyday never thought of that.
So to lose less rpm as possible use low volts and high turn counts
Down side little current handling and the speed is gonna be crawling so efficiency will suffer.

Think between you all its answered here

That's not at all what MadRhino is saying. He's saying it doesn't make any difference, because the % change in voltage is the same. Just give up trying to invent a condition where it's better to use a slow wind motor, because there isn't one unless you want to go really slow and you're sure you'll never want better performance.

To me it's pitiful that anyone needs to suffer with a slower bike at the end of a ride than the beginning, and that's especially true for those who want to stick to some arbitrary letter of the law written by people who are extremely prejudiced against ebikes. The way around the problem is to build the bike with excess capability and limit the top speed via the controller. Then you can ride the speed you want at all points in the discharge cycle as well as on uphill grades and into headwinds.

One thing I have noticed when comparing Clyte H3548 and Clyte H3525 at higher power levels in the motor simulator is that the slower wind Clyte H3525 at high voltage will do better than the faster wind Clyte H3548 at low voltage.....in climbing and top speed.

H2525 @ 72v with 20" wheel:
32.5 kph climbing 14% grade with 61.1 watt-hours per km power consumption
43.3 kph top speed on flat ground

H3548 @ 36v with 20" wheel:
22.6 kph climbing 14% grade with 62.9 watt-hours per km power consumption
40.6 kph top speed on flat ground

https://ebikes.ca/tools/simulator.html?motor=M3525&cont=PR&batt=B7210_DT&wheel=20i&grade=14&hp=0

https://ebikes.ca/tools/simulator.html?motor=M3548&cont=PR&batt=B3626_GA&wheel=20i&grade=14&hp=0

https://ebikes.ca/tools/simulator.html?motor=M3525&cont=PR&batt=B7210_DT&wheel=20i&grade=0&hp=0

https://ebikes.ca/tools/simulator.html?motor=M3548&cont=PR&batt=B3626_GA&wheel=20i&grade=0&hp=0

With the H3548 being almost twice the wind as the H3525 the results should be a lot closer. The only thing I can think of is that the phase wires are too thin to optimally handle the higher current needs of the 36v and this is why the slower wind H3525 is so much better at climbing.

Regarding the comparison above.....

......Phaserunner is not able to supply enough amps to the fast wind motor (Clyte H3548) during the climb.

 

[Ianhill]

The difference need to be expressed as a percentage. If a slow winding does 30 mph at 72v it will have the same % speed drop at lvc as a fast winding doing the same top speed at 48v, simply because the fast winding will drop more rpm per volt, proportionally.

Learn something everyday never thought of that.
So to lose less rpm as possible use low volts and high turn counts
Down side little current handling and the speed is gonna be crawling so efficiency will suffer.

Think between you all its answered here

That's not at all what MadRhino is saying. He's saying it doesn't make any difference, because the % change in voltage is the same. Just give up trying to invent a condition where it's better to use a slow wind motor, because there isn't one unless you want to go really slow and you're sure you'll never want better performance.

To me it's pitiful that anyone needs to suffer with a slower bike at the end of a ride than the beginning, and that's especially true for those who want to stick to some arbitrary letter of the law written by people who are extremely prejudiced against ebikes. The way around the problem is to build the bike with excess capability and limit the top speed via the controller. Then you can ride the speed you want at all points in the discharge cycle as well as on uphill grades and into headwinds.

I get madrhino pointed out the kv and volt relationship.
I'm pointing out the diff of both hubs run on a same apples 10s battery a 2T will lose 60rpm down to 3.7v where as a 16T will lose only 11.25 rpm granted the 2T is at 4-5 hundred rpm and the 16T 83-94.5 rpm so it will be much lower speed but that mph drop then will be very little won't it ?
I see thats the percentage dropped is the same for both turn variants and the torque drop would mean normally gearing would be used to spin the wheel faster and then it would equal out but with a hub and the rim being the gear then it's just got no option but to pull more amps to climb ?

I don't now all or pretend to I try he helpful and give my previous experiences but clearly from the advice is to run a motor within it's design parameters and don't try be cocky as it will melt in the end just like my scooter did same as Dogman dan winter time ok summer fryed halls

 

[ebike4healthandfitness]

A) I would much rather have larger diameter winding wire that is shorter which means less resistance but it can take more power which means low turn count motors (3T, 4T etc)

B) then a motor with thinner diameter winding wire that is longer which means more resistance can cant take as much power which means high turn count motors (8T etc)

Been running some simulations in the motor simulator keeping battery pack and controller constant. The only variables I am changing is wheel diameter and motor winding (Clyte H3525, H3540 and H3548).

All wheel diameter and motor winding combinations I matched up to produce the same top speed on flat ground, but the smallest diameter wheel with the fastest winding (i.e. lower turn count) climbs fastest while at the same time running coolest and using the least amount of power of km. This tested on various grades.

P.S. One thing to keep in mind is that as tire diameter decreases a person who wants to pedal along with the motor will need a larger chainring and/or smaller cogs in order to keep up.

 

[Ianhill]

A) I would much rather have larger diameter winding wire that is shorter which means less resistance but it can take more power which means low turn count motors (3T, 4T etc)

B) then a motor with thinner diameter winding wire that is longer which means more resistance can cant take as much power which means high turn count motors (8T etc)

Been running some simulations in the motor simulator keeping battery pack and controller constant. The only variables I am changing is wheel diameter and motor winding (Clyte H3525, H3540 and H3548).

All wheel diameter and motor winding combinations I matched up to produce the same top speed on flat ground, but the smallest diameter wheel with the fastest winding (i.e. lower turn count) climbs fastest while at the same time running coolest and using the least amount of power of km. This tested on various grades.

P.S. One thing to keep in mind is that as tire diameter decreases a person who wants to pedal along with the motor will need a larger chainring and/or smaller cogs in order to keep up.

Mxus 4t on 10s 10wh per mile is not to bad, I had a 16tooth rear single and 52t front 20 inch rim peddle at 16 mph to peddle at 28mph on a 20 will be spinning legs like no tomorrow.

That's about the limits of what I got to help sorry fella I'm sure you will pick wise though.

 

[Balmorhea]

All wheel diameter and motor winding combinations I matched up to produce the same top speed on flat ground,

That's a sign that the speed is power limited and not motor RPM limited. It's likely that every one of those windings is faster than optimal for the voltage and current you specified.

The slowest winding that still reaches the top speed you want, is the best one for efficiency and low speed torque.

To your calculator play, I suggest adding this power and speed calculator:
http://www.kreuzotter.de/english/espeed.htm

And this road speed calculator:
https://www.4qd.co.uk/road-speed-calculator/
(Hub motor reduction ratio is 1.)

By figuring out how much power you need to maintain a certain speed, and how many RPM that speed represents, you can more easily match motor output to wheel diameter to winding, to find the top speed you want with optimum efficiency and low speed performance.

For what it's worth, I don't think you are likely to get a combination that tops out at 20 mph by itself but still provides any assist at 28 mph, unless you use some kind of active electronic limiting. If you manage it, it would probably be by using a winding that's far too fast for your available power, and is inefficient and hot at 20 mph without pedaling.

To my knowledge, Leaf Bike is the only hub motor seller that will provide any winding you request at no extra charge, at least for their 1000W and 1500W models. They'll also furnish RPM figures for different windings if you ask them. It's sales "at" leafbike dot com.

 

[Balmorhea]

To me it's pitiful that anyone needs to suffer with a slower bike at the end of a ride than the beginning,

That's because you don't understand bicycles or the principle of enough is enough.

It's OK, boomer.

 

[serious_sam]

but the smallest diameter wheel with the fastest winding (i.e. lower turn count) climbs fastest while at the same time running coolest and using the least amount of power of km. This tested on various grades.

For a hub motor, smaller wheel will always produce better efficiency for a given speed and load, because it doesn't need to produce as much torque for that given load (smaller wheel= more leverage). Since heat is proportional to torque squared, reducing the torque requirements significantly reduces heat produced, and therefore increases efficiency.

The fastest winding is a bit of a red herring in that equation. It just allowed you to keep the same speed with the same controller but smaller wheel. But the winding itself didn't increase the efficiency, it is just a variable in the system you used to keep the speed constant.

 

[john61ct]

OK, so what about this scenario?

No gearing for this thought experiment, just to clarify pack voltage / winding/Kv questions.

Very high weight loaded tandem / cargo rig, long steep mountain climbs, none of those fixed values, #1 goal is just to maximise them.

Need maximum torque at low speeds, starting from a dead stop I may not always be able to get the rig rolling from human pedal power, e.g. if pointing up hill.

25" tire diameter or greater is required, cannot go smaller. Any system voltage between 24V and 72V is OK, whatever works out best, never mind cost issues due to higher voltage, plenty of room for a huge battery pack, spending over a grand on that is NP.

A top speed under 25mph on the flat is fine, but no need to use the winding choice to act as the limiter,

I like the idea of the drivetrain being more powerful than required, and using electronics to limit speed and phase amps.

If the winding choice does not give more torque at lower speeds (and **that* is a main question!)

then can the winding choice help put the top efficiency speed (Wh per mile) into the 15-20mph range?

Maximum range is #3 goal, after reliability / longevity.

I am willing to pay more for high ampacity BMS other kit, controller will likely be FOC and full-featured anyway, likely also using CAv3 if it adds value

_______
Part II - please clarify using just the above first

Does the question become easier stating Nucular 24F as a given? What is maximum phase amps there? Would it work well with the lower pack voltage range?

I assume a Phaserunner is too small for this use case, unless going to 2WD. . .

 

[Balmorhea]

Very high weight loaded tandem / cargo rig, long steep mountain climbs, none of those fixed values, #1 goal is just to maximise them.

Need maximum torque at low speeds,

Any system voltage between 24V and 72V is OK, whatever works out best, never mind cost issues due to higher voltage,

Any winding can put out the same maximum torque, as long as there's the same amount of copper. A winding that's three times as fast can take three times as much current (the winding, not the plugs and phase wires). If parts cost and availability are not factors, then choose a voltage that looks nice to you on paper. It doesn't matter.

Most of us would rather use electrical components that are cheap commodities, not expensive custom or Russian-made parts. When you settle on a voltage that allows you to use cheap commodity parts, then that constrains you to those winding turn counts that do what you want to do, at the voltage and power level you decided upon.

 

[ebike4healthandfitness]

All wheel diameter and motor winding combinations I matched up to produce the same top speed on flat ground,

That's a sign that the speed is power limited and not motor RPM limited. It's likely that every one of those windings is faster than optimal for the voltage and current you specified.

Kv was matched up with wheel diameter so that didn't happen. (Example: H3548 has 20% higher Kv than H3540 so I used a custom wheel diameter on H3540 that was 20% greater in the diameter to compensate.)

 

[john61ct]

Any winding can put out the same maximum torque, as long as there's the same amount of copper. A winding that's three times as fast can take three times as much current (the winding, not the plugs and phase wires)...It doesn't matter.

@John in CR do you agree?

Others?

So, does the "three times" numerically apply to Kv or the "T" windings number or both?

"Taking" lots more current, does that translate to running cooler at that low speed power (torque) level?

 

[goatman]

Learn something everyday never thought of that.
So to lose less rpm as possible use low volts and high turn counts
Down side little current handling and the speed is gonna be crawling so efficiency will suffer.

Think between you all its answered here

That's not at all what MadRhino is saying. He's saying it doesn't make any difference, because the % change in voltage is the same. Just give up trying to invent a condition where it's better to use a slow wind motor, because there isn't one unless you want to go really slow and you're sure you'll never want better performance.

To me it's pitiful that anyone needs to suffer with a slower bike at the end of a ride than the beginning, and that's especially true for those who want to stick to some arbitrary letter of the law written by people who are extremely prejudiced against ebikes. The way around the problem is to build the bike with excess capability and limit the top speed via the controller. Then you can ride the speed you want at all points in the discharge cycle as well as on uphill grades and into headwinds.

One thing I have noticed when comparing Clyte H3548 and Clyte H3525 at higher power levels in the motor simulator is that the slower wind Clyte H3525 at high voltage will do better than the faster wind Clyte H3548 at low voltage.....in climbing and top speed.

H2525 @ 72v with 20" wheel:
32.5 kph climbing 14% grade with 61.1 watt-hours per km power consumption
43.3 kph top speed on flat ground

H3548 @ 36v with 20" wheel:
22.6 kph climbing 14% grade with 62.9 watt-hours per km power consumption
40.6 kph top speed on flat ground

https://ebikes.ca/tools/simulator.html?motor=M3525&cont=PR&batt=B7210_DT&wheel=20i&grade=14&hp=0

https://ebikes.ca/tools/simulator.html?motor=M3548&cont=PR&batt=B3626_GA&wheel=20i&grade=14&hp=0

https://ebikes.ca/tools/simulator.html?motor=M3525&cont=PR&batt=B7210_DT&wheel=20i&grade=0&hp=0

https://ebikes.ca/tools/simulator.html?motor=M3548&cont=PR&batt=B3626_GA&wheel=20i&grade=0&hp=0

With the H3548 being almost twice the wind as the H3525 the results should be a lot closer. The only thing I can think of is that the phase wires are too thin to optimally handle the higher current needs of the 36v and this is why the slower wind H3525 is so much better at climbing.

Regarding the comparison above.....

......Phaserunner is not able to supply enough amps to the fast wind motor (Clyte H3548) during the climb.

im reading this thread and kind of shaking my head, i look at your simulator for 36v and 72v, thats not what i experience at 17s/60v with my PR connected to my HS3540/11rpm/v in a 26od wheel or my xf40/11 rpm/v in 20 inch wheel, both bikes cruise up the hills at 50km/h never overheat. 48v and 52v will blow 20amp controller with those motors

try the phaserunner at 60v/3548 motor statorade/7% hill and you get 45km/h or 28mph and the phaserunner is putting out 50amps and motor temp is 76c never overheat

 

[ebike4healthandfitness]

A) I would much rather have larger diameter winding wire that is shorter which means less resistance but it can take more power which means low turn count motors (3T, 4T etc)

B) then a motor with thinner diameter winding wire that is longer which means more resistance can cant take as much power which means high turn count motors (8T etc)

Been running some simulations in the motor simulator keeping battery pack and controller constant. The only variables I am changing is wheel diameter and motor winding (Clyte H3525, H3540 and H3548).

All wheel diameter and motor winding combinations I matched up to produce the same top speed on flat ground, but the smallest diameter wheel with the fastest winding (i.e. lower turn count) climbs fastest while at the same time running coolest and using the least amount of power of km. This tested on various grades.

P.S. One thing to keep in mind is that as tire diameter decreases a person who wants to pedal along with the motor will need a larger chainring and/or smaller cogs in order to keep up.

Mxus 4t on 10s 10wh per mile is not to bad, I had a 16tooth rear single and 52t front 20 inch rim peddle at 16 mph to peddle at 28mph on a 20 will be spinning legs like no tomorrow.

That's about the limits of what I got to help sorry fella I'm sure you will pick wise though.

According to the Sheldon Brown Gear calculator a person would need 61T chainring and a 11T cog in order to get 28 mph using 90 rpm.

https://sheldonbrown.com/gear-calc.html

 

[Balmorhea]

"Taking" lots more current, does that translate to running cooler at that low speed power (torque) level?

No. The same motor architecture with the same amount of copper makes the same amount of heat to produce the same amount of torque, no matter how many turns in the winding. You're just trading volts and amps to get a given amount of torque and RPM from different windings. This is something that Johnny CR, Luke LFP, and I all agree is true.

If there's a difference, it's in the cables and connectors outside the motor, where high currents could result in increased losses (and most likely require a heavier and more expensive harness).

Where John and I differ is that he doesn't have a problem with spending a lot of extra money on controllers, batteries, plugs, cables etc, so he can use a faster wind than necessary, and a much more powerful motor system than necessary for the job-- and he thinks that's the right choice for everybody else too. I prefer using widely supported voltages with good economies of scale, and I believe that the right amount of power to use is just enough to do the job, and no more.

And of course, he thinks his electric motorcycles are morally equivalent to bicycles, which I don't. If he lived where I do, he'd be obligated to get registration, liability insurance, and a driver's license with motorcycle endorsement. I think that's only right, as well as fair to other motorcyclists and real bicyclists.

 

[MadRhino]

Nowhere but in your twisted mind, does an ebike need to be morally equivalent to a bicycle. Morality has nothing to do with it. There are different uses, legislations and applications all over the world and your personal morality is not taken into account.

 

[john61ct]

Yes morality is not the right word there.

Even legal requirements are in many places not effectively enforced

and very often the law is an ass, and the right thing to do morally is to fight to change it, in the meantime break it, if it is practical to do so in your context / location.

I agree that it is worth spending more for extra capacity, even if it is only rarely needed, the line between "barely suitable" and "not enough" is too greyscale fuzzy for my level of experience.

The limiting factor isn't spending a few hundred more on robust components

it would be unduly adding too much weight, reducing the amount of energy kWh I can carry, thus shorter travel range,

also less food and propane and drinking water etc meaning more frequent resupply trips.

 

[ZeroEm]

My morality is in question by posting in this discussion. I think it is off the rails.

How practical is 72v (or 60v) for a street legal direct drive set-up meant for climbing and sub 28 mph speed?

It's practical if you like 60V or 72V and money is not an issue. It only takes 48V 25A controller in a 26" wheel for <=28mph

 

[ebike4healthandfitness]

It only takes 48V 25A controller in a 26" wheel for <=28mph

Yes, 28 mph with a 26" wheel, 48v battery and 25 amp controller is possible with a Clyte H3548:

https://ebikes.ca/tools/simulator.html?cont=C25&motor=M3548&mass=170&batt=B4816_GA&hp=0

.....but that same 25 amp controller limits the climbing speed and climbing efficiency of the fast H3548 wind compared to the slower H3540 and H3525 winds:

https://ebikes.ca/tools/simulator.html?cont=C25&motor=M3548&mass=170&batt=B4816_GA&grade=7.5&hp=0

H3548 up 7.5% grade yields a speed of 10.9 kph at a power consumption of 96.6 wh per km

https://ebikes.ca/tools/simulator.html?cont=C25&motor=M3540&mass=170&batt=B4816_GA&grade=7.5&hp=0

H3540 up 7.5% grade yields a speed of 15.3 kph at a power consumption of 75.8 wh per km

https://ebikes.ca/tools/simulator.html?cont=C25&motor=M3525&mass=170&batt=B4816_GA&grade=7.5&hp=0

H3525 up 7.5% grade yields a speed of 17.6 kph at a power consumption of 66 wh per km.

 

[donn]

I think you will occasionally see "moral equivalent" used in a rather broad sense, where it's simply about a fundamental distinction that may matter to people. I don't care to take on the motorcycle vs. bicycle question here myself, but indeed it may matter to people.

 

[Ianhill]

The way the law sees it is all that matters to some and the law see it in most places is a bike should not outperform a human only assist them and not increase top speed.

I'll be honest if I took to the road most drop handles would chew my arse I can only do 34mph but I ain't got no peddles and ride off road id proberly buy a drop handle ebike and add a vesc to make a decent speed bike that uses little energy and it's gonna walk under their noses been a factory looker.

 

[ebike4healthandfitness]

It only takes 48V 25A controller in a 26" wheel for <=28mph

Yes, 28 mph with a 26" wheel, 48v battery and 25 amp controller is possible with a Clyte H3548:

https://ebikes.ca/tools/simulator.html?cont=C25&motor=M3548&mass=170&batt=B4816_GA&hp=0

.....but that same 25 amp controller limits the climbing speed and climbing efficiency of the fast H3548 wind compared to the slower H3540 and H3525 winds:

https://ebikes.ca/tools/simulator.html?cont=C25&motor=M3548&mass=170&batt=B4816_GA&grade=7.5&hp=0

H3548 up 7.5% grade yields a speed of 10.9 kph at a power consumption of 96.6 wh per km

https://ebikes.ca/tools/simulator.html?cont=C25&motor=M3540&mass=170&batt=B4816_GA&grade=7.5&hp=0

H3540 up 7.5% grade yields a speed of 15.3 kph at a power consumption of 75.8 wh per km

https://ebikes.ca/tools/simulator.html?cont=C25&motor=M3525&mass=170&batt=B4816_GA&grade=7.5&hp=0

H3525 up 7.5% grade yields a speed of 17.6 kph at a power consumption of 66 wh per km.

If I change the wheel diameter in the above examples from a 26" to 20" something very interesting happens:

https://ebikes.ca/tools/simulator.html?cont=C25&motor=M3548&mass=170&batt=B4816_GA&grade=7.5&hp=0&wheel=20i

H3548 up 7.5% grade yields a speed of 18.8 kph at a power consumption of 65.2 wh per km

https://ebikes.ca/tools/simulator.html?cont=C25&motor=M3540&mass=170&batt=B4816_GA&grade=7.5&hp=0&wheel=20i

H3540 up 7.5% grade yields a speed of 19.2 kph at a power consumption of 60.5 wh per km

https://ebikes.ca/tools/simulator.html?cont=C25&motor=M3525&mass=170&batt=B4816_GA&grade=7.5&hp=0&wheel=20i

H3525 up 7.5% grade yields a speed of 20.6 kph at a power consumption of 56.4 wh per km.

Firstly, the performance across the board increases (in both speed and energy efficiency)......but notice that the three different windings are now grouped much more closely together.

What that tells me is that larger wheels are more sensitive to differences in winding under loads that stress the amp capacity of the controller.