DIY built. (Leaf, MXUS, MP5)

[sisachosudo]

Hello guys,

After overthinking the whole issue a bit too much, I decided to start building my own project using an old bike. I am a bit lost with numbers, Amps, volts and the like so I will be updating this post with more doubts in the future.

Let me give you a picture of the initial situation:

• I want the motor to be a rear Direct Drive. It has to last many years and be efficient at high speeds. I plan to pedal quite a lot and I don’t mind helping after stops.

• The battery will be allocated in the downtube, using the bottle cage screws. Still to be decided but it will be in the range of 48 or 52V and 13.5 - 17Ah battery pack. Still reading about the cell types in order to make a decision.

• Motor will be mounted in a 700c sized wheel

• Very seldom I will be pulling a bike trailer (15 to 20kg) in flat terrain at low speed.

• Integrated controller and torque sensor are a big plus.

• I prefer cassette over freewheel.

I am looking after something to get 1000W continuous and will be limited later on if needed. After checking plenty of options, I am left with the following motors:

1.- Magic Pie V5: If I am not mistaken, the only one with built in controller.
2.- Leaf 1000W (is the 1000W direct drive?)
3.- MXUS 300X: The lightest of all the options at 6.4kg.

I would love to hear your opinions about these three motors. Do they all have torque sensor? Can they be configured to ride with PAS or throttle only?
I guess all of them have the option of reg.braking.

Thank you very much for taking the time to read this post.

 

[amberwolf]

None of htem have torque senosrs, because those would not be in the motors--those are usually in the BB, replacing the original one, so you usually have to take the pedal cranks off to install it. Very few controllers support torque sensors, but there are options like the Cycle Analyst v3.x that can add that support to just about any controller, if you get a torque sensor the CA supports. (see http://ebikes.ca or the CA3 beta thread here on ES).

PAS is also not in the motors, it is a function of the controllers. The MP series often has controller built into the motor (there's lots of posts and threads about the Magic Pie series if you want to read what's been written already), but which functions it has I don't remember.


Regen is also not in the motor, it's also a function of the controllers. But the motor does have to be a DD motor, not a geared hub, to support it.


There are literally thousands, hundreds of thousands, of different controllers out there, and they each have their own set of functions and capabilities and power and voltage limits. So picking a controller is the hard part...and then actually getting the controller to do what you wanted can be a task, depending on the wiring and programming. (and if the vendor actually sends you the right controller, or has any info on what to do with it, for a number of the Chinese sales sites, ebay, etc).

Sometimes the controller / etc comes with the motor in a kit (though it may not be pre-setup with the same connectors on each, so it may or may not just plug in and go). If that controller does what you want, then you're all set.


Integrated controllers (built into the motor) are a disadvantage in that they make heat, and the motor makes heat, so they both make the heat problem worse, and can cause problems with shutdown when you need it, or even failures, depending on the actual power levels you use vs how much heat the system can shed.




The battery itself will need to be able to supply the current the controller puts out, so don't get a controller that supplies more than the battery can handle, or it will shorten the life (and range) of the battery.

But the current has to be enough to drive the motor hard enough to do what you want it to. If you want quick acceleration, you may need a fair bit of current; similarly hill climbing may need that too.

Then the motor has to be able to support that kind of current for the time needed to do those types of things.


Gotta go to work now, so more later if there's time.

 

[sisachosudo]

None of htem have torque senosrs, because those would not be in the motors--those are usually in the BB, replacing the original one, so you usually have to take the pedal cranks off to install it. Very few controllers support torque sensors, but there are options like the Cycle Analyst v3.x that can add that support to just about any controller, if you get a torque sensor the CA supports. (see http://ebikes.ca or the CA3 beta thread here on ES).

PAS is also not in the motors, it is a function of the controllers. The MP series often has controller built into the motor (there's lots of posts and threads about the Magic Pie series if you want to read what's been written already), but which functions it has I don't remember.


Regen is also not in the motor, it's also a function of the controllers. But the motor does have to be a DD motor, not a geared hub, to support it.


There are literally thousands, hundreds of thousands, of different controllers out there, and they each have their own set of functions and capabilities and power and voltage limits. So picking a controller is the hard part...and then actually getting the controller to do what you wanted can be a task, depending on the wiring and programming. (and if the vendor actually sends you the right controller, or has any info on what to do with it, for a number of the Chinese sales sites, ebay, etc).

Sometimes the controller / etc comes with the motor in a kit (though it may not be pre-setup with the same connectors on each, so it may or may not just plug in and go). If that controller does what you want, then you're all set.


Integrated controllers (built into the motor) are a disadvantage in that they make heat, and the motor makes heat, so they both make the heat problem worse, and can cause problems with shutdown when you need it, or even failures, depending on the actual power levels you use vs how much heat the system can shed.




The battery itself will need to be able to supply the current the controller puts out, so don't get a controller that supplies more than the battery can handle, or it will shorten the life (and range) of the battery.

But the current has to be enough to drive the motor hard enough to do what you want it to. If you want quick acceleration, you may need a fair bit of current; similarly hill climbing may need that too.

Then the motor has to be able to support that kind of current for the time needed to do those types of things.


Gotta go to work now, so more later if there's time.

That's a very useful lesson there Amberwolf. Appreciated!

I thought PAS, torque sensor and regen were some features available depending on the motor you choose. I see they are not.

I am going through Neptronix's post regarding the LEAF 1500W motor. It is a ton of information to digest and sometimes I get lost with the numbers. Sorry if I ask something that has been posted that before.
Do you know if all the benefits from that LEAF 1500W reviewed by Neptronix are also applicable to the 1000W?

I am planning on buying a full kit containing one of the 3 motors listed above and the battery will be from em3ev matching the controller/motor.

One thing that surprises me is that a Leaf 1000W kit is less than half the price of the MXUS (from Grin Tech.)

Leaf Kit here: http://www.leafbike.com/products/di...w-rear-hub-motor-bike-conversion-kit-902.html

MXUS Kit here: https://www.ebikes.ca/shop/electric...rive/mxus-rear-cassette-kit-advanced-pas.html

Is there that difference in quality of the motor or other components of the kits? If you believe there is a better kit out there... I am all ears.

Thank you!

 

[amberwolf]

I thought PAS, torque sensor and regen were some features available depending on the motor you choose. I see they are not.

They can be available based on the *kit* or *system*, but not on the motor itself.

Do you know if all the benefits from that LEAF 1500W reviewed by Neptronix are also applicable to the 1000W?

I don't know enough about either to say. Depends on their contruction and design. Since neither is likely actually designed or made by "leafmotors", but probably from other manufacturers, they could both be completely different. I'm sure there's a thread or threads about both of them that give all the necessary info to compare; possibly even a direct comparison thread, somewhere. If both are listed on the http://ebikes.ca/simulator, under ALL MOTORS, then you can compare them directly under the conditions you'd be using them under.

One thing that surprises me is that a Leaf 1000W kit is less than half the price of the MXUS (from Grin Tech.)

They're very different kits, and you can get a whole lot more with the Grin setup, especially if you're getting the torque sensing BB and Cycle Analyst.

It also comes with a professional wheel build with the correct thickness Sapim brand spokes for the rim used, so they're thin enough to tension properly without damaging the rim.

It also has better controller options (for either higher peak power, or higher voltage, or for more features in a smaller space (phaserunner)). The controller, along with the Cycle Analyst and torque sensor, can provide all of the same functions as the Leaf controller, only can be better, plus the torque control itself.

Can come with a nice torque arm (or two, better).

Instead of having to use the crappy levers that come with kits, you can instead get the Tripwire sensor(s) to use with your existing levers.

Has the option to pre-add Statorade to the motor to help it shed heat if you think you want to use it at higher power levels than it's made for, for more than moments at a time.

You have the option of either of two windings, which will affect the startup torque and top speed, depending on load, controller current, and battery voltage. (see the simulator link on the page to determine which one suits your needs better).


The Leaf kit doesn't do any torque sensing, doesn't ahve the option for it that I can see, just the typical on/off PAS (meaning, you set the amount of assist you want on the LCD, then whenever you pedal at all, you get all of that level of assist immediately, and you stop pedalling, and get no assist), and throttle (which would let you have anything from zero to full).

It (probably) comes with an automated wheel build that hasn't been touched by a professional wheel builder, so it may or may not be true, and is probably not tensioned correctly (because doing so would likely crack the rim, over time if not immediately, becuase the generic noname spokes are too thick for the rim used).

Doesn't list a torque arm, so you'd have to invent something (or buy one from someone else like Grin or EM3EV).

Don't know if it has more than one winding option.


I don't know anything about Leaf's support/warranty history, but Grin's has generally been good (with some exceptions that I've read about here on the forum).


The motors themselves are probably the same kind of quality between the two places. Performance of each you can check out and compare in the simulator, if they're both listed there.

Grin has a number of different motors that would probably do what you're after, which you can check out in the simulator. (My uses are more extreme than most, for torque and burst/continuous power, though I don't need much speed, so I don't know that what I'd use would be appropriate for yours ).


You could also get the Leaf kit and add the Grin CA & torque sensor, though you'd need to configure everything yourself (whereas if you get the kit from grin you can have them make sure its' already configured), and you'll probably have to change some connectors on either the Grin stuff or teh Leaf stuff.

 

[neptronix]

You never defined what high speed was.
Your motor choice depends totally on how fast you want to go and what kind of hills you wanna take.

Can't help you without specifics.

Although you could play with the ebikes.ca motor simulator and find out.

https://www.ebikes.ca/tools/simulator.html

If your top speed is 30mph then i like the 30mm wide 9C for it's weight.
Leafmotor has horrible controllers but their wheels are built pretty damn well, so you'd want to pair that with a controller + throttle + screen combo from someone else. Make sure you get a controller that's programmable so you can increase or decrease the power to your tastes.

 

[sisachosudo]

Thank you guys.

You never defined what high speed was.

Because I am not even sure of that :?
It will be my first e-bike, I know I would like to go fast but not sure how safe I will feel going at 40 km/h in a bike on flat terrain.
I would say that my goal is to average 35-40 km/h but after reading the forum I believe that after trying the e-bike I will be loving the +40km/h zone.

I use the simulator a lot even that it is difficult for me to fully understand the numbers. Today I got a big surprise when playing with it as the 9C+ 2707 seems to have more range than the MXUS or LEAF (850 watts/h battery).
Maybe these two motors are not the best options when looking for range? It is a pity that Grin does not offer the 9C+ as a rear hub, only front.

My daily commute will be 30km with a couple of demanding hills but I don't mind slowing down there, there is no need in going uphill at 25km/h, I just don't want to arrive at the office needing a shower or having to deal with a sweaty back when I am cycling at 0-5°C outside.
I cycle to work everyday since 3 years ago and I know I will be pedaling enough.

The more I look, the more lost I find myself
I don't mind paying a bit more now to have something that will serve me for more years.

 

[sisachosudo]

Hello, I've been playing with the simulator for a long time today.

Am I doing the right thing to compare two motors?

- I set the motor, battery and controller type.
- Vehicle parameters: 700C, MTB and 100kg.
- Human power set to 125w
- Grade: 2%
All these specs above are equal for both systems, only the motor type is different.

Then I adjust the throttle in both systems until I get the speed I believe I will be needing.
With these specifications I can see in the table which is below the graph, the range I will get with each motor.

I am getting very similar readings regarding range for the MXUS, Leaf and 9C. Tricky decision.

But after going through the complete post of amberwolf and being myself a newbie I will leave the Leaf aside and aim for a kit from a quality vendor like em3ev or Grin. I don’t have the knowledge to buy cheap and upgrade/configure it myself.

One extra question. How can I simulate the Magic Pie V5?

Thanks again.

 

[neptronix]

I use the simulator a lot even that it is difficult for me to fully understand the numbers. Today I got a big surprise when playing with it as the 9C+ 2707 seems to have more range than the MXUS or LEAF (850 watts/h battery).
Maybe these two motors are not the best options when looking for range? It is a pity that Grin does not offer the 9C+ as a rear hub, only front.

The trick with selecting a motor is finding one that's appropriately sized for the speed you want to travel. Each motor has an efficiency curve and there is a sweet spot.

When comparing motors, throw the most amps at it possible ( 40A+ ). Starve a motor for amps it needs to travel at X speed and it will run inefficiently. This will skew comparisons because different motors require different amount of amps to produce X rpm..

The more I look, the more lost I find myself
I don't mind paying a bit more now to have something that will serve me for more years.

Yeah, my first 6 months on here were reading and figuring out what the hell to build. Even still, it took 10 builds to zero in on the dream bike. Welcome to the club :lol:

The best thing you can do is buy more than you need because you might catch the speed bug later...

A MAC is an excellent starter motor because it's happy doing 40kmh - 53kmh and comes in at a pretty light 10lbs/~4kg.
The Bafang G310 has to be my current favorite for lower power at 5.6lbs/2.55kg and is good for the 30-40km/h range of speed.

Direct drive is a good idea when you need more power than the MAC and/or need to go offroad / live in pothole central which will destroy the planetary gears of any geared motor.

MXUS 3000x would be my personal choice for a smaller DD just because it's nicely weight optimized for the power it outputs. It's roughly on par with the much lighter MAC.

 

[sisachosudo]

Each motor has an efficiency curve and there is a sweet spot.

If I understand well, the sweet spot is at the top of the efficiency curve and the ideal situation is when the speed I am planning to cycle falls right into that spot. Am I right?

I learn more with one of your replies than with 1h reading by myself Thanks.

 

[donn]

The trick with selecting a motor is finding one that's appropriately sized for the speed you want to travel. Each motor has an efficiency curve and there is a sweet spot.

When comparing motors, throw the most amps at it possible ( 40A+ ). Starve a motor for amps it needs to travel at X speed and it will run inefficiently. This will skew comparisons because different motors require different amount of amps to produce X rpm.

Well, that's one thing to look at, but it doesn't appear to me to be the whole picture. For example ... given a MXUS 3005 on a 5% grade, at 40 amps I get 43kph but an overheating outcome; at half throttle, 25kph, no overheating (and twice the range, due mainly to wind resistance I suppose.) The computed motor efficiency is a couple percentage points higher at full throttle, but in every way that matters, it appears to be less efficient - shorter battery range, maybe shorter motor life. I could have picked a motor that worked a lot better at 40 amps under a load, but that's kind of my point, you have the knowledge you need to apply that rule sensibly, but not everyone does.

If I were shopping for another direct drive motor, I'd be interested in how much cogging drag. Mine seems to me to have very little; maybe it's the same with every modern DD, maybe there are some that are much worse, or better, no idea. My impression is that they know how to make motors that are a lot better in this respect than the early ones that gave DD that reputation, but does everyone do that now. Are there tradeoffs?

 

[neptronix]

Each motor has an efficiency curve and there is a sweet spot.

If I understand well, the sweet spot is at the top of the efficiency curve and the ideal situation is when the speed I am planning to cycle falls right into that spot. Am I right?

I learn more with one of your replies than with 1h reading by myself Thanks.

You're welcome.

The sweet spot for efficiency is at the top of the efficiency curve, yeah. The sweet spot for power is always past that and at a lower efficiency point.

Looking at this dyno plot for my favorite motor today, the leafbike 1500w, we see that peak efficiency happens at 1000W, which correlates to the amount of power you'd be using at 30mph, so you could say this would be the optimal motor for 30mph.
But looking at the graph, we also see that we have pretty good efficiency at 2075 watts inputted because we are only losing 276 watts to heat. That's about what a motor of this size can continually shed with a little help... IE get into a tucked position, pedal, throw hubsinks on it, statorade, etc :thumb:

2000w is required to travel at 40mph so we can call this a 40mph capable motor with a little help on the cooling.

donn basically points out that you need overhead in your design for those times that you're gonna climb a monster hill or ride against wind etc. Yes, you need to 'derate' the top speed you're aiming for to reduce the continuous load if you have to occasionally climb hills and such so that your motor can cool off between pushing 2-3x the load on flat ground.