Low speed DD Leaf motor

[Mattias]

Hi guys. Leaf motor say the can make a 80rpm@48v motor.
http://m.leafbike.com/mobile/products_detail.php?ProId=1077

I tried to contact them to get some info about efficiency and maybe a graf but they always refer to the website or a copy-paste answer. I don't know if this is a good motor for my 4 wheel Quad. I now run Mac 16t motors and they are still to fast and get hot if pushed hard.

I also asked if the could build a left and a right motor so that they turn in same direction but only got answered: This motor support clockwise and counter clockwise. Important,should use a controller to drive this motor reverse/backward.

I don't think they understood my question...

I have a leaf DD 1500w in my regular e-bike that work perfect and never gets warm how much I push it, so I would really want to try that on the quad, but if it doesn't work it will be hard to sell a motor that slow.

What do you think, is this a good alternative to my MAC motor?
Will it be efficient at that low rpm and not get warm... Will it have more torque and better slow speed characteristics?

Here is more info on my quad.
https://r.tapatalk.com/shareLink?url=https%3A%2F%2Fendless-sphere%2Ecom%2Fforums%2Fviewtopic%2Ephp%3Ft%3D82322&share_tid=82322&share_fid=55725&share_type=t




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[dogman dan]

80 rpm is realllllllllly slow. So it sounds like a good idea if your use is that slow.

Not sure what voltage the 80 rpm spec is for, so hard to say how slow that really is. If it's 80 rpm at 12v, then that would be slow, but not crazy slow. But 80 at 36v is a wheelbarrow motor.

FWIW, the low speed motor EBK uses for trikes and cargo bikes is 194 rpm @ 36v. It's plenty slow for 15 mph top speed trikes. So 80 rpm @ 36v is crazy slow.

Like I said though, if that slow with heavy loads is your goal, then you need the slow wind in whatever motor you are choosing.

If the load is not so heavy, you can run a big DD motor VERY slow, and remain VERY efficient. No need at all for special winds until you are loading the motor a lot. Sounds like maybe you are loaded up pretty heavy, if you are heating up your current motors.

What is pointless, is to feed a low rpm motor a lot of volts to speed it up. I did that for a time on motors similar to that leaf we are discussing, but it only worked to the general watt limit of the motor. So if you want 1500w per motor, upping voltage to increase the watts will work ok, run efficient, stay cool, etc. Go 3000w per motor, and it will just make heat, regardless of the winding chosen. Because the motor is rated for 500w. Needs more copper to pull 3000w. The low rpm motor will merely stop pulling hard at lower rpm.

This shit is confusing, it took years for John in CR to pound into my moronic brain. But the simple rule is this. Keep your motors within their rating, then choose the winding and wheel size that suits the speed you want. If Slooooooow and heavily loaded per motor is what you want, then a slow motor works great. Otherwise, with light load, no real advantage to a slow motor at all.

 

[neptronix]

That would be the right winding for a 300+ volt setup. You still need to spin the motor to a high RPM in order to make good continuous power. At 80RPM, you are probably looking at perhaps 100-200 watts continuous power.

Much like a gas motor.. the faster she spins, the more power she makes. A Honda Civic would blow past a 16 cylinder car that only spins to 1,000rpm.

But they would not put a 16 cylinder engine into a Honda Civic. Why install an 800 pound engine when a 200 pound engine would do just fine?

 

[Mattias]

80 rpm is realllllllllly slow. So it sounds like a good idea if your use is that slow.

Not sure what voltage the 80 rpm spec is for, so hard to say how slow that really is. If it's 80 rpm at 12v, then that would be slow, but not crazy slow. But 80 at 36v is a wheelbarrow motor.

FWIW, the low speed motor EBK uses for trikes and cargo bikes is 194 rpm @ 36v. It's plenty slow for 15 mph top speed trikes. So 80 rpm @ 36v is crazy slow.

Like I said though, if that slow with heavy loads is your goal, then you need the slow wind in whatever motor you are choosing.

If the load is not so heavy, you can run a big DD motor VERY slow, and remain VERY efficient. No need at all for special winds until you are loading the motor a lot. Sounds like maybe you are loaded up pretty heavy, if you are heating up your current motors.

What is pointless, is to feed a low rpm motor a lot of volts to speed it up. I did that for a time on motors similar to that leaf we are discussing, but it only worked to the general watt limit of the motor. So if you want 1500w per motor, upping voltage to increase the watts will work ok, run efficient, stay cool, etc. Go 3000w per motor, and it will just make heat, regardless of the winding chosen. Because the motor is rated for 500w. Needs more copper to pull 3000w. The low rpm motor will merely stop pulling hard at lower rpm.

This shit is confusing, it took years for John in CR to pound into my moronic brain. But the simple rule is this. Keep your motors within their rating, then choose the winding and wheel size that suits the speed you want. If Slooooooow and heavily loaded per motor is what you want, then a slow motor works great. Otherwise, with light load, no real advantage to a slow motor at all.

It's rated at 48v and 1500w. I don't need to go fast or use mor power than that.

 

[Mattias]

That would be the right winding for a 300+ volt setup. You still need to spin the motor to a high RPM in order to make good continuous power. At 80RPM, you are probably looking at perhaps 100-200 watts continuous power.

Much like a gas motor.. the faster she spins, the more power she makes. A Honda Civic would blow past a 16 cylinder car that only spins to 1,000rpm.

But they would not put a 16 cylinder engine into a Honda Civic. Why install an 800 pound engine when a 200 pound engine would do just fine?

As a car mechanic I see what you mean but I don't think it's the whole truth... You can also build a V8 to work on high rpm in a F1 car or build one for a tow truck that gives a lot power at low rpm. They could theoretically have​ the same volume but it's the internal design that make the difference. Same apply to electric motors, here are​ the key words efficiency and torque and they are different depending on the design.

This leaf motor is rated at a whooping 90% efficiency and that's really good. But that is at a specific rpm "sweet spot" that you can see in a graph on the website. This efficiency sweet spot moves depending on the design and I would like to see a graph for a high turn "slow motor".

If I'm not totally lost I would say a low turn motor have more total power but the efficiency sweet spot are at a high rpm and so if you want to go slow you need a gearing so that you can stay in your high rpm.

With a high turn motor the efficiency sweet spot are at a lower​ rpm and you might not need that gearing to stay efficient and cool


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[neptronix]

Yes, the 90% efficiency happens around 300rpm ( see the dyno graph i posted in the main thread ).
Unfortunately the winding won't change that point very much.. you still have to spin it up. A low turn count wants amps to do that.. a high turn count wants volts..

The motor design you are thinking of is the equivalent of running an engine at 2,000rpm because 150 volts is your limit with standard ebike controllers. You will hit about 320rpm unloaded on 150v, or maybe 270rpm loaded. It will end up making less continuous power than my setup.

It is like putting 1.6L headers, cam spacing, and intake on a v8 so you can maximize your low end torque.. you still end up with really low power density for the motor. You could have made more peak torque by gearing the motor down and letting it flow good at the highest RPM it could tolerate.. ( oldschool Honda engine mentality )

The truth with electric motors is that the faster you spin them, the better they do*. The most power dense and efficient motors are RC motors that spin in the 10,000's of RPMs!
You can play with the ebikes.ca simulator to prove this with a hub. It will give you a good approximation of what the real world is like.

* = this is limited by bearings and thickness of laminations. Above a certain point, a hub motor will experience iron losses that are far too high and create too much heat. A 4T leaf motor in a 16" wheel on 150v would probably run into this problem. Although it'd be making over 200ft-lbs of torque from a stall. Your problem is then the metal that holds the axle in place:lol:

 

[spinningmagnets]

A quad is much heavier than a bicycle, and a low-RPM Leafbike motor with high-amps is a bad idea on a bike. Run a chain from the stock spocket to a jackshaft, and then connect the jackshaft to some kind of motor. I would use a Lightning Rods big block at a minimum, but I am sure there are several viable choices that would work.

 

[cal3thousand]

If the bike runs too fast on a MAC 12T at 48V, then I would go with these options before replacing the motors:

• Go down to 36V on the pack and increase the pack's Ah capacity. This will reduce the speed that the motor is trying to go by 25% and likely give you a bump in range.
• Setup your CA to limit your max speed and power to levels that make your motor happy. The MAC can handle the power levels that you are trying to go, but at 48V is trying to go too fast for the terrain.
• I'd actually change motors before this option, but: Run the motors through a single reduction to reduce your wheel speeds.

 

[neptronix]

Honestly i'd be going with a very large chain drive motor with the right reduction, instead of any hub.

Many of them have better efficiency across the band.. lower weight per kW outputted.. and more compatible with the drivetrain of an ATV.

You will also want something more in the league of 4kw continuous or more.

 

[amberwolf]

I also asked if the could build a left and a right motor so that they turn in same direction but only got answered: This motor support clockwise and counter clockwise. Important,should use a controller to drive this motor reverse/backward.

I don't think they understood my question...

Unless I'm missing something, they are correct.

Perhaps I misunderstand your question, too, or perhaps you misunderstand the issue(s) involved? Some detail below, in case it helps clear up things:



AFAIK, those motors are not made with slanted (offset) lamination stacks, so they are not directional. Simply reversing the phase and hall order would drive the same motor, flipped over for one side, the opposite direction that the original order would spin in the original orientation on the other side.

Some motors, like the old X530x and X540x Crystalyte hubs, *are* directional, because they have offset lamination stacks, which appear to have slanted slots. Makes them more efficient and/or less "cogging" drag in one rotation direction, but it also makes the problems worse in the other direction.

Most motors are made symmetrically, so they can be spun either direction, so you can just flip it over to run it the other way.

The only potential issue is if you need a thread-on freewheel to work on a flipped motor, as it would unscrew itself, but I doubt that's an issue on your quad.

 

[Mattias]

I also asked if the could build a left and a right motor so that they turn in same direction but only got answered: This motor support clockwise and counter clockwise. Important,should use a controller to drive this motor reverse/backward.

I don't think they understood my question...

Unless I'm missing something, they are correct.

Perhaps I misunderstand your question, too, or perhaps you misunderstand the issue(s) involved? Some detail below, in case it helps clear up things:



AFAIK, those motors are not made with slanted (offset) lamination stacks, so they are not directional. Simply reversing the phase and hall order would drive the same motor, flipped over for one side, the opposite direction that the original order would spin in the original orientation on the other side.

Some motors, like the old X530x and X540x Crystalyte hubs, *are* directional, because they have offset lamination stacks, which appear to have slanted slots. Makes them more efficient and/or less "cogging" drag in one rotation direction, but it also makes the problems worse in the other direction.

Most motors are made symmetrically, so they can be spun either direction, so you can just flip it over to run it the other way.

The only potential issue is if you need a thread-on freewheel to work on a flipped motor, as it would unscrew itself, but I doubt that's an issue on your quad.

Ok very good info. I thought you only could do that with sensorless motors... I guess we are lost in translation sometimes

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[Mattias]

Yes, the 90% efficiency happens around 300rpm ( see the dyno graph i posted in the main thread ).
Unfortunately the winding won't change that point very much.. you still have to spin it up. A low turn count wants amps to do that.. a high turn count wants volts..

The motor design you are thinking of is the equivalent of running an engine at 2,000rpm because 150 volts is your limit with standard ebike controllers. You will hit about 320rpm unloaded on 150v, or maybe 270rpm loaded. It will end up making less continuous power than my setup.

It is like putting 1.6L headers, cam spacing, and intake on a v8 so you can maximize your low end torque.. you still end up with really low power density for the motor. You could have made more peak torque by gearing the motor down and letting it flow good at the highest RPM it could tolerate.. ( oldschool Honda engine mentality )

The truth with electric motors is that the faster you spin them, the better they do*. The most power dense and efficient motors are RC motors that spin in the 10,000's of RPMs!
You can play with the ebikes.ca simulator to prove this with a hub. It will give you a good approximation of what the real world is like.

* = this is limited by bearings and thickness of laminations. Above a certain point, a hub motor will experience iron losses that are far too high and create too much heat. A 4T leaf motor in a 16" wheel on 150v would probably run into this problem. Although it'd be making over 200ft-lbs of torque from a stall. Your problem is then the metal that holds the axle in place:lol:

Ok I got it. But if we look at the rc world which I also is deep down into. You would choose a hi turn motor for a rock crawler and a lower turn for a racing buggy and they use the same battery voltage. I special ordered my Mac motors directly from the manufacturer with 16turn and a single side shaft for this quad. It's been working great! Always stays around 60degres Celsius when hiking in off road terrain. Only when pushed really hard it can get hot, like in high grass up a steep hill and almost flipping over

Remember that I have 4 of these motors and they​ help each other. So I'm not very far away from perfect. They have​ a total of 5kw together.

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[Mattias]

A quad is much heavier than a bicycle, and a low-RPM Leafbike motor with high-amps is a bad idea on a bike. Run a chain from the stock spocket to a jackshaft, and then connect the jackshaft to some kind of motor. I would use a Lightning Rods big block at a minimum, but I am sure there are several viable choices that would work.

I know a chain is the best way to go if this was the only thing to worry about.
It now wheight 65kg and 110kg with driver and ready to go. I don't think that is much consider I have 4 motors and 5000watt.

I would say that it's not perfect but good enough. I also need to be able to lift it up myself on the back of the car when traveling. With hub motors there are less moving things that can break and probably less wheight.

I have an other schassi that I will try chain drive on. But now I'm only interested in this DD hub. I was so impressed by it. I think it's a 5t on my bike and I have a 24" wheel and it is so much fun to drive. Wheeles away so easy and the torque and feeling is so good, max speed is 45km/h@48v. And it never gets warm. That's why I started this thread. Could this be a alternative motor for the quad. I mean it would run even cooler with 20" wheel and then having 2 of these in the back it feels like a winner and I love to see a graph of a 150rpm motlr, it would be between 8-10T maybe?

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[amberwolf]

Ok very good info. I thought you only could do that with sensorless motors... I guess we are lost in translation sometimes

Oh, and one other caveat: it won't work with geared motors due to the freewheel/clutch inside most of them, but those very few without one would still work that way, unless they have offset either the lamination stacks or the hall sensor placement (something they might do since the clutched ones are normally never run in reverse anyway).


BTW:

*ALL* hubmotors are sensorless, or can be used that way, AFAIK. It's just the *controllers* that may require (or not) that the motors have sensors.

AFAIK you can use any hubmotor that has sensors with controllers that don't bother to read those sensors.

 

[amberwolf]

With hub motors there are less moving things that can break and probably less wheight.

While the former is generally true, the latter is generally not, as far as DD hubmotors go for the power density especially at low speed. Geared hubmotors may weigh less because they are generally smaller than the DD motors, and their motor spins several times as fast for the same power, and thus can use less lamination steel, copper, magnets, back iron, and weigh less (as the gearing part will not usually weigh as much as the difference of the other things).

So while it would depend on how you did the gearing down and mounting and which motors you used, a non-hubmotor solution would probably be lighter for the same power.

The wheels could also be stronger mechanically because you wouldnt' be depending on random-quality-steel-axles with flawed designs (stress risers) to support the wheels, and could use known-quality/good-design single-ended-axle (or regular) wheels that would be unlikely to break the way hubmotor axles do (usually at the stress risers where diameters change sharply, and or where the cheap metal has been hollowed out for wires).