Leafmotor 2000w

[Blacksword]

When asking about fat bike hub motors this week someone pointed me at the Leafmotor and I saw some really excellent threads about leaf motors from the archives.

I wondered if anyone has any experience with the 2000w direct drive version of this motor and how much this could be reasonably overclocked?

https://www.leafbike.com/products/beach-snow-fat-bike-kit/26-inch-48v-52v-2000w-rear-hub-motor-beach-snow-fat-tire-bike-conversion-kit-1088.html

What would be the best winding to request to climb long slow hills without frying the internals?

 

[Balmorhea]

"Overclocked" is imprecise. Are you talking about raising volts or amps? For long slow climbs, it's probably best to leave input power and volts at their recommended levels, and get a slow winding. But if you use a somewhat faster winding and increase the current available, you may be able to climb faster and reduce motor heating that way.

Leaf customer support has always told me unloaded RPMs for a given motor with different turn counts when I asked. If you plug your parameters into a power and speed calculator like
http://www.kreuzotter.de/english/espeed
you can get a sense of how much power you need, and then you can set the motor winding to deliver adequate power at a corresponding speed. I use
https://www.4qd.co.uk/road-speed-calculator/
to convert speed into RPM and vice versa.

Understand that a direct drive hub motor like Leaf won't give you both slow climbing ability and fast cruising ability.

 

[Blacksword]

Thanks yes sorry 'overclocked' that was a little for effect, I build a lot of PCs, but yes pushing high current and or voltage for the fun of experimentation.

I am really not interested in speed, its a bonus 20mph on throttle only would make me happy, but its long slow hill climbing ability I want. I am new to this so exploring the hub motor landscape and trying to understand as much as I can right now.

Is there any primer on windings and performance on hills I can go do some learning with? I'd like to know what to ask them for intelligently. I am not sold on the leaf motor only, many folks have suggested other alternatives QS and MXUS, I am looking for a good fit for a fat bike without underpowering it or alternatively on the extreme side turning it into a motorcycle, I want to be able to haul the weight of the frame and me around on some 30 mile long backpacking days in hilly terrain.

So much fantastic knowledge here from all the forum members if some of the regulars ever run a convention or publish a sequential video series or book - I would say take my money $$$

 

[Balmorhea]

Using a fat bike, rather than a plus MTB, normal MTB, or fat tire touring bike, will cost you weight and range. That difference between 3" and 4" tires is decisive in terms of efficiency. You can do what you want with any of the above, but with a fat bike, you'll need more battery and more power to do the same job.

I don't know what the RPM/volt for different windings of the 2kW fat bike motor are, but to use the figures for the 48V/1500W motor-- 8 turn winding yields an unloaded speed of 290 RPM. For a 29" outside diameter fat bike wheel, that's a free speed of 25 mph. That means close to 20 mph cruise speed, and peak power at about 12-13 mph.

If you ask sales at leafbike dot com, they'll give you unloaded RPM numbers for different windings of the motor you have in mind. 80% of the free speed is the efficiency sweet spot, and 50% of the free speed is peak power RPM. Climbing at speeds below 50% of the unloaded speed is increasingly inefficient and causes rapid heat buildup.

If you are going to use a 26" fat bike, pick the motor winding that gives 250 to 300 RPM at your battery's voltage, that is if you want 20 mph cruise and competent climbing. You'll get more range and better climbing with a slower winding, but at the expense of cruise speed.

 

[John in CR]

Long slow steep climbs are not the domain for any direct drive motor without gearing them down with either a small wheel or getting them out of the wheel and using a gear reduction. It is very load dependent though, as light people can get away with much more before heat problems arise. The Kv of the motor really bears no relevance, a common misconception. Cooling mods can make a big difference, since sealed motors can't dissipate much heat, especially at low speeds.

 

[John in CR]

... You'll get more range and better climbing with a slower winding, but at the expense of cruise speed....

These kinds of statements are patently incorrect. Otherwise identical motors wound to different Kv's are capable of identical performance (speed, torque, efficiency, hill climbing, etc.) They just require different combinations of voltage and current (same power), to achieve identical results. Differences in performance or efficiency only arise when you arbitrarily limit one of the variables, because you are locked into a certain battery voltage or current limits of a controller you already possess. Even then the PWM operation of the controller mitigates much of the difference.

 

[Balmorhea]

... You'll get more range and better climbing with a slower winding, but at the expense of cruise speed....

These kinds of statements are patently incorrect.

You surely knew I was talking about using the same battery and controller, because I said so in the part of the paragraph you trimmed out. But you have some peculiar axe to grind.

There is no good reason for most people to deviate from cheap and easy-to-find 36V to 52V batteries and controllers when they can, at no extra cost, pick a motor winding to work with the power system instead of the other way around. The motor winding is arbitrary. Other factors, less so.

If you start with a given battery and controller, a slower winding will give you more torque, lower top speed, and more range in almost every case.

But go ahead and imagine a 2V, 1000A bike motor system if it makes you feel warm/fuzzy.

 

[John in CR]

... You'll get more range and better climbing with a slower winding, but at the expense of cruise speed....

These kinds of statements are patently incorrect.

You surely knew I was talking about using the same battery and controller, because I said so in the part of the paragraph you trimmed out. But you have some peculiar axe to grind.

There is no good reason for most people to deviate from cheap and easy-to-find 36V to 52V batteries and controllers when they can, at no extra cost, pick a motor winding to work with the power system instead of the other way around. The motor winding is arbitrary. Other factors, less so.

If you start with a given battery and controller, a slower winding will give you more torque, lower top speed, and more range in almost every case.

But go ahead and imagine a 2V, 1000A bike motor system if it makes you feel warm/fuzzy.

There's no good reason to perpetuate myths and common misconceptions. The OP doesn't say anything about using a controller or battery he already has, yet you insist on spouting absolute nonsense about slow wind motors giving more range and climbing hills better. Any time I see anyone repeating those old debunked myths I protest loudly, because it's those myths prevent a real understanding of how our systems perform. The better our group's understanding, the more likely we'll be able to get manufacturers to provide the needed motor specs, which are Kv and phase-to-phase resistance,...and the real reason these 2 quite easy to obtain measurements aren't commonly given as standard specifications is because even many manufacturers don't have the solid foundation of understanding. You share some great bicycle related knowledge, so please learn the basics about motors. Kv gives us both rpm/volt and torque/amp . The torque limits of a motor are set by the iron core and the magnetic circuit (how the copper is wound bears no relevance.), and the phase-to-phase resistance tells us how much heat current creates in the copper which is especially important since the copper heat losses increase with the square of current.

 

[Balmorhea]

[There is no good reason for most people to deviate from cheap and easy-to-find 36V to 52V batteries and controllers when they can, at no extra cost, pick a motor winding to work with the power system instead of the other way around. The motor winding is arbitrary. Other factors, less so.

If you start with a given battery and controller, a slower winding will give you more torque, lower top speed, and more range in almost every case.

There's no good reason to perpetuate myths and common misconceptions. The OP doesn't say anything about using a controller or battery he already has, yet you insist on spouting absolute nonsense about slow wind motors giving more range and climbing hills better.

Thing is, most of us aren't electrical engineers who build our own controllers and chargers. We don't get to freely choose whatever random voltage we like. We are working with common voltages that offer us lots of commercial product options and power levels. If you want the most choices, you use 48V equipment. And once you've nailed down the number of volts and amps you're working with, the way you modify the torque and speed of a hub motor system is by choosing an appropriate motor winding.

Trying to work at the problem backwards is a mistake, at least from the standpoint of having commercial products easily available.

I'll reiterate: when you know the voltage and power you're working with, using a slower motor winding will give you more range, better climbing, and a lower top speed. This is true and you know it.

 

[Blacksword]

Well I would prefer to start with readily available cost effective batteries and voltages since I'm just learning here and will most likely be building a 52v pack.

So far I've found quite a few confusing posts on windings but nothing that explains it clearly for a beginner, if someone could turn me to a clear guide I'd be grateful. I need the average Joe guide

How do I determine which voltage and current and controller is required to drive a particular motor and windings? Where should a person start when designing the system.

 

[2old]

Start with your requirements and budget, then work from there. For instance, I wanted 30 mph or so with 25 mph cruising for my "errand" bike. Turns out (learned this from a member who doesn't seem to post now) a 1000w, 48V motor with 30 amp controller and 52V, 10 ah battery was perfect. Five or six years later, it still works.

 

[John in CR]

...I'll reiterate: when you know the voltage and power you're working with, using a slower motor winding will give you more range, better climbing, and a lower top speed. This is true and you know it.

That's the most ridiculous set of qualifications I've seen anyone use on ES to try to prove their incorrect statements about slow wind motors being better on hills were in fact correct. Not only do you want to fix both voltage and current to prove your point, but since you didn't also fix gearing it's still not necessarily true.

 

[Balmorhea]

Well I would prefer to start with readily available cost effective batteries and voltages since I'm just learning here and will most likely be building a 52v pack.

So far I've found quite a few confusing posts on windings but nothing that explains it clearly for a beginner, if someone could turn me to a clear guide I'd be grateful. I need the average Joe guide

In the most general terms? Suppose you have a motor with one turn of wire around each pole. Let’s say if you connect a battery, it turns at 1000 RPM with a torque of 1 unit. If you rewind the motor with two turns of wire (that are half as heavy) around each pole and connect the same battery, the same electrical current will cause the magnetic field to be twice as strong. The motor will turn with 2 units of torque but at only half the RPM. With three turns, you get 3 units of torque and one-third the rpm.

The math is actually more complicated than that; there are more factors than winding and wire gauge alone. But that’s the basic principle.

The motors we use have a fixed rpm per volt, which is abbreviated kV, and a fixed torque per amp. Different windings of the same basic motor change these values in inverse proportion to each other.

 

[Balmorhea]

...I'll reiterate: when you know the voltage and power you're working with, using a slower motor winding will give you more range, better climbing, and a lower top speed. This is true and you know it.

That's the most ridiculous set of qualifications I've seen anyone use on ES to try to prove their incorrect statements about slow wind motors being better on hills were in fact correct. Not only do you want to fix both voltage and current to prove your point, but since you didn't also fix gearing it's still not necessarily true.

We are discussing a direct drive hub motor, like the title says. My original assertion stipulated the same battery. What is your damage? Can your mind not keep a context between successive posts in the same thread?

 

[John in CR]

...I'll reiterate: when you know the voltage and power you're working with, using a slower motor winding will give you more range, better climbing, and a lower top speed. This is true and you know it.

That's the most ridiculous set of qualifications I've seen anyone use on ES to try to prove their incorrect statements about slow wind motors being better on hills were in fact correct. Not only do you want to fix both voltage and current to prove your point, but since you didn't also fix gearing it's still not necessarily true.

We are discussing a direct drive hub motor, like the title says. My original assertion stipulated the same battery. What is your damage? Can your mind not keep a context between successive posts in the same thread?

You vary the gearing of a DD hubmotor by changing the wheel size. Stick to bicycle related issues where you have useful input instead of wasting time attacking someone who refutes your incorrect statements with factual input.

 

[Bullfrog]

Thanks yes sorry 'overclocked' that was a little for effect, I build a lot of PCs, but yes pushing high current and or voltage for the fun of experimentation.

I am really not interested in speed, its a bonus 20mph on throttle only would make me happy, but its long slow hill climbing ability I want. I am new to this so exploring the hub motor landscape and trying to understand as much as I can right now.

Is there any primer on windings and performance on hills I can go do some learning with? I'd like to know what to ask them for intelligently. I am not sold on the leaf motor only, many folks have suggested other alternatives QS and MXUS, I am looking for a good fit for a fat bike without underpowering it or alternatively on the extreme side turning it into a motorcycle, I want to be able to haul the weight of the frame and me around on some 30 mile long backpacking days in hilly terrain.

So much fantastic knowledge here from all the forum members if some of the regulars ever run a convention or publish a sequential video series or book - I would say take my money $$$

Go get a BBSHD (mid drive) and a 52v battery...put a 30T front sprocket on the motor and use a 22T White Industries Freewheel on the rear hub. You can climb a tree AND run about 20 mph without over heating the motor.

At speeds below about 20 mph you are going to over heat any DD Hub Motor and any Geared Hub Motor if you stop and start a lot or climb steep hills for very long.