High Torque Hub Motors

[skyeg3]

Hey Yall,

I am trying to find high torque, low speed hub motors for my quad bike project. Looking at videos of the mxus 3000, It looks like they spin way faster than I need. i want this buggy to be comfortable climbing hills slowly. Are there any geared hub motors?



please see picture. And here is my build thread:

https://endless-sphere.com/forums/viewtopic.php?f=10&t=74352

Thank you!

 

[amberwolf]

There are lots of geared hubmotors. If you search for that term you'll find lots of discussions about the various kinds, and there are several included on http://ebikes.ca/simulator as well (though they may not be listed as geared or direct drive, you can easily google the model numbers listed there and find out which is which).

 

[dogman dan]

If you want a rock crawler, then what you must do, is use some kind of external gear reduction to match your tire rpm, with the motors optimal continuous duty rpm.

You need to do something like the stokemonkey, or other type motor with sprocket, so you can dial in that low gear.

Dual bafang BBs02? Dual GNG kits? Or just some large powerful scooter motors with a sprocket on them?

Love your design for going 10 mph to 60 mph, but hub motors are simply the wrong choice for a crawler. Even if you could find low speed winds of the 3000w muxus, I seriously doubt they would be ideal. So that even takes rewinding them yourself out of the picture.

Move the motors in your design up a foot, and you can then add a chain or belt drive reduction gear.

 

[Drunkskunk]

The slower you run a motor, the less efficient it becomes when producing torque. If you try to run a normal direct drive hub motor at 6mph while crawling over things, it's going to over heat fast, and suck your battery empty at blinding speeds.

If you want low speed torque, you need some form of gear reduction. I think you also need reverse, so a geared hub won't work.

 

[skyeg3]

The slower you run a motor, the less efficient it becomes when producing torque. If you try to run a normal direct drive hub motor at 6mph while crawling over things, it's going to over heat fast, and suck your battery empty at blinding speeds.

If you want low speed torque, you need some form of gear reduction. I think you also need reverse, so a geared hub won't work.

I seem to be missing something. maybe Im also stressing "rock crawling" too much. How much of a reduction do the geared hub motors typically have? 2:1? I want one gear that maxes out at 25-30mph also this will have 20" bmx wheels on it which should help. Are there really no geared hub motors that have good torque without a chain reduction? Also I don't understand why a geared hub motor could not have reverse.

 

[cwah]

Just get a 16" wheel on a high torque mxus. Get a 36v and 200A controller and you should have mega outpuy and low speed to climb anything at 15kmh

 

[Simonvtr]

I have a maxus v2 45 6 Turn on a 17" moped rim.
Max speed @ 49 volts is 18mph on a recumbent trike.
I think the mxus 6t would be a good fit and it would not over heat.

 

[skyeg3]

I have a maxus v2 45 6 Turn on a 17" moped rim.
Max speed @ 49 volts is 18mph on a recumbent trike.
I think the mxus 6t would be a good fit and it would not over heat.

I think that (mxus 3000w 6t) sounds like the ticket. I'll give it more volts too. Also it will have two so should be pretty fast!

 

[Lurkin]

Gearbox would surely be the way to do this properly... but which one will be light enough to justify it?

 

[dogman dan]

Didn't know you could get that muxus in a 6t.

But it will still suffer if you are climbing a big hill very slow. if you get to the top in time, no melty. If you don't get there in time, smoke comes out the motor.

But if your needs really are more like you will travel at least 10mph all the time, or most of it, the muxus 6t certainly has the balls to get up a steep hill. It's more a terrain issue that has caused me to smoke hub motors, than the grade. If it's so rough I have to keep stopping, or slowing to 5mph, that's when I've melted motors every time.

So it depends on the roads you will ride. If 10-20 mph is even possible without crashing, go for the dual 6t muxus.

No doubt, two of those muxus motors running a 3000w max each, will have plenty of power to go up the trail fast! And they will have the thermal mass to take some abuse for awhile.

FWIW, the 6t muxus will NOT have more torque than the 3t, and in fact, perhaps even less. But when "less" is still dealing with a big powerful motor, then you can get by fine with less torque. It's still plenty, especially with two! 8)

What the 6t will do, is give you less excess speed you didn't want, and more fine throttle control when going slower. I'm still a big fanboy of the slow winding motors, even if I was confused and wrong about how they work for years. All I knew then was, it took me longer to smoke the low speed motors than the higher speed ones, using 26" wheels. You'd be using 20", which will help a lot. But it's still not going to be an efficient set up for crawling 2-5 mph, ever.

 

[John in CR]

Just get a 16" wheel on a high torque mxus...

The smaller wheel that equates to lower gearing is good advice. Then what follows including posts from others that follow is pure horseshit. All the different winds of the mxus3000 produce the same heat for the same torque, so there is no "high torque" version. Slow or fast is the difference, and all you have to do is use a lower voltage with higher current for the same power input with the fast motor to get the same results as with higher voltage lower current using the slow motor. Torque is the same. Hill climbing is the same. Heat is the same. Efficiency is the same.

 

[dogman dan]

Yes, heat will be the same if the motor is not stalled. And all the winds, if stalled, will heat.

But the slow wind stalls at a lower speed. So they do, indeed, tend to heat less when ridden too slow up hills. Because they can tolerate a bit slower. Not because of one winding being more efficient per se, but one winding being less stalled than the other.

It's not a difference really in the motor, so much as what speed they like. As you say, the difference is the speed. He wants slower speed, so a slower motor will suit him best.

Stalling two muxus 3000w motors, now that will be VERY HARD to do. In 20" wheel, it might be actually impossible to stall them for more than a half a second at a time. With 6000w of power, he'll hardly be overloading those motors up most hills. So with that much power, both types very likely will see no difference in heating. But he might very well have a harder to control at low speed vehicle, if he uses a 3t winding. So the real reason to choose the low speed, is to have better throttle control at 0-5 mph.

 

[John in CR]

Yes, heat will be the same if the motor is not stalled. And all the winds, if stalled, will heat.

But the slow wind stalls at a lower speed. So they do, indeed, tend to heat less when ridden too slow up hills. Because they can tolerate a bit slower. Not because of one winding being more efficient per se, but one winding being less stalled than the other.

It's not a difference really in the motor, so much as what speed they like. As you say, the difference is the speed. He wants slower speed, so a slower motor will suit him best.

Stalling two muxus 3000w motors, now that will be VERY HARD to do. In 20" wheel, it might be actually impossible to stall them for more than a half a second at a time. With 6000w of power, he'll hardly be overloading those motors up most hills. So with that much power, both types very likely will see no difference in heating. But he might very well have a harder to control at low speed vehicle, if he uses a 3t winding. So the real reason to choose the low speed, is to have better throttle control at 0-5 mph.

What part of different winds being the same motor don't you get? When people who don't know any better set their rigs up incorrectly, the conclusions they reach must be ignored. The physics don't change and it doesn't matter how many times you try to change the wording, those high turn count motors you love to promote don't climb hills any better in any way. They don't make more torque (at any speed). They don't make less heat (at any speed). Since you apparently insist on setting them up incorrectly, it turns out that the slow motor is actually easier to burn up due to the much longer much thinner copper.

 

[cwah]

so what motor are you recommending him John? and why?

 

[Simonvtr]

My understanding of motor is very little compare to other members on this forum.
But from my many years of RC 4wd racing I know that a lower turn motor means you have less copper mass which means your motor will heat up faster and eat up alot of amps.
Compared to a higher turn motor will take longer to heat up.
But in RC racing you are racing against the clock. So in a normal race which last 5 mins you want to match the motor/gear ratio to deplete the battery pack in that given amount of time.
Also you match the motor/gear to the type of track.
In a large oval track I would use a very low turn motor and high gear ratio to get max speed.
But in a more technical track I would use a higher turn motor and gear for best exit torque coming out of a turn.

If all things stay the same wheel size and voltage.
Going up the same steep hill what would be the difference between a 4t and a 6t?
[ PLEASE EDUCATE ]
My understanding is a 4t is most efficient at higher rpm compared to a 6t.
It will overheat faster then a 6t because it would want to reach the rpm the motor was designed to do?
It would eat up alot of amps trying to get to that rpm?
A 6t runs at lower rpm and will take less amps to reach that lower rpm?

 

[John in CR]

Simon,

Just because your toy motors weren't wound properly has nothing to do with modern hubmotors. They fit as much copper as possible around each tooth, so whether it's 4 turns with 15 strands on each turn or 10 turns with 6 strands of the same size copper on each turn, the motor works out to being exactly the same motor. The 15 strand bundle will also be shorter as well as thicker, and the physics work out such that exactly the same heat is created for the same torque at the same rpm. Input power and efficiency are exactly the same, and the only difference is the voltage and current.

Vendors who don't understand, or do understand and still make "high torque" claims are just part of the problem. Others may have RC motor experience like Simon who experienced real differences from running the same load which had improper gearing for the new higher rpm and/or the motor maker was lazy and simply changed the number of turns without changing the thickness of the wire. We've even had an experienced EE on here talk about the same nonsense, because his experience with washing machine motors was the same...ie all they did was change the turn count since they never really looked at efficiency, since even the worst windings still fell within the heat, torque, and rpm specs called for. Based on some pics of the stators of one of the well known geared hubbie manufacturers, I suspect they take a similar lazy way approach that results in substandard higher Kv motors, so of course they get hotter.

 

[skyeg3]

Basically my benchmark for hill climbing ability is this hill near my house in Pacifica, CA. It's a steep dirt road about 1 mile long with an elevation gain of 1000'. If I could get up that in one go without stopping that would be great. (see pic of hill). As for top speed - I don't see needing to go any faster than 30mph. The buggy and rider combined weight will be 300-400 lbs and there will be two of these motors - one for each rear wheel. I am thinking about having a 72v 20ah pack for each motor.

Can anyone explain what is the actual physical difference between these motors? Like what does 4t and 6t actually mean? Sounds like I need to learn a bit about electric motor design.

Appreciate all the help.

 

[Chalo]

For all the talk about "same torque for same heat regardless of winding", we're all aware that 72V at 20A is a lot more practicable than 7.2V at 200A. And that's what it would take for a one turn motor to do a ten turn motor's job. It's not torque alone we look for, but a speed range that's relevant to our application.

When the relevant speed range we're looking for is slow, the winding of the motor should be slow. Low voltage/high current isn't just inconvenient and expensive to get a controller for; it also means much heavier cables, more expensive switches and breakers, fewer options for connectors, less reliable highly parallel batteries, and so forth.

 

[John in CR]

Lies and misrepresentations is all the slow wind advocates can come up with to support their past purchase mistakes instead of admitting to being duped. Back in the beginning I too was duped by the same "slow wind high torque motor" myth. Because it seems intuitive, it's hard to let go, and some still refuse. No, changing how the identical amount of copper is arranged inside a motor does not make it climb hills better or make more torque. It unequivocally is not like a change in gearing.

Unlike Chalo would have you think, of course 36V is inherently safer and less prone to failure than 72V. That's why the cell phone you walk around with in your pocket is only 3.7V. There's absolutely no reason to go to a lethal voltage for a 30mph bike. Plus once you realize you want 30mph even up hills and into headwinds it's much easier to get there, but if you set up at high voltage off the bat, you have to buy a whole new system, including new motors. Setting up for 30mph on 36V is definitely better, much better, especially since you've already realized that using dual hubbies is the way to go for this build.

So what if the wiring weighs a tiny bit more. At least then the wires aren't so spindly that just bumping them a couple of times breaks a wire, causing a short and blowing a controller, or worse, starting a fire. It's not like I'm talking about needing cabling the size of car battery leads. The controllers would actually be cheaper at the lower voltage, but I'd suggest starting with more flexibility going forward and get programmable controllers capable of a range of voltages instead of a fixed voltage.

 

[dogman dan]

Whatever John, all I'm still saying is any motor heats less if you stall it less. Then I said it would be all but impossible to stall two big motors putting out 6000w for long enough to matter. So in this case, heating will be unlikely to be an issue. On too steep a hill, that buggy is just going to spin tires and grind rubber off the tires.

But he'd have a harder to control vehicle when riding it slow, if the motors are faster wind than if they are slow wind.

So uhh, can you stand it if we say a slower motor is good for going slow? The OP titled the thread High torque hub motors. And I have to agree, two muxus 3000w motors sounds pretty high torque.

But the 6t is NOT higher torque than the 3t. It's just gooder for slower.

 

[John in CR]

Say "whatever" all you want, but that doesn't change the fact that you have been the biggest advocate of the pointless slow wind motors with every single argument being baseless and misleading, including the latest version of your twist on words by trying to say they are less likely to stall. On top of that the last post insinuates that they're more easily controlled at low speeds, another fallacy.

Yes I call them slow and low power due to our upper end voltage limitation with controllers. Low speed is handled by the controllers and the magic of PWM. You do realize that my 100mph+ ebike runs just fine at just 5 or 10mph, don't you? Sure the steering is sluggish going that slow, but that's only because of the high speed geometry of my bike and has nothing to do with the motors. I run a 30s pack, so a 10s pack for 37V nominal puts the OP right about where he wants to be as long as he doesn't make the slow wind mistake you're trying to talk him into.

I know you're an honorable person Dan, and that you don't want to intentionally mislead people, so it's high time you stop. They don't make more torque. They don't climb hills better or more efficiently. They can't can't push heavier loads. They don't have a lower risk of heat failure. They don't allow you to run a bigger wheel. They aren't less likely to stall. In fact, the only situation where it could be an advantage to buy a slow wind hubbie is if you were already married to a high voltage, and the speed and power would be too high with a faster wind motor. That's not the case here.

No, setting up for 36V is much better. If performance is still a bit too high, it can still be dialed back with simple controller program changes. If, as is more typical, more performance is desired, then 48V is a simple step up with noticeable results, or 72V a signficant step up but still simple. Starting at 72V or 74V, there's nowhere to go that's simple and cheap, or nearly as reliable.

 

[Chalo]

Why stop at 36V? Why not 3.6V? If you could find a big enough cell, it'd be awesome. Power leads as fat as hot dogs would make your bike look super potent.

 

[teslanv]

If you want to use a "normal" controller with smallish phase wires and a modest battery, the 6T MXUS motor is the best winding for you application.
John is absolutely correct that every winding of the MXUS can produce the same total torque, but he refuses to admit that it's more practical to use a "slow" winding in certain applications such as the one the OP has proposed.
There is theory, which John insists on ramming down our throats, and then there is sensibility.
But the correct answer is actually that the OP should get a Bafang BBSHD, and pair it with a small (42T) front chainring, and a 34T large sprocket cassette/freewheel.
Buy your BBSHD kit here.
http://lunacycle.com/cyber-monday/bafang-bbshd-1000w-mid-drive-kit-in-stock/

 

[dogman dan]

The slower motor is good for bikes that plan to ride slow. For this guy, running two 3000w motors in 20" wheels, no stalling will be happening whatever motor he uses. But he'll have better throttle control with a slower motor, when riding 5 mph.

 

[John in CR]

Why stop at 36V? Why not 3.6V? If you could find a big enough cell, it'd be awesome. Power leads as fat as hot dogs would make your bike look super potent.

The controllers and hubmotors don't exist.