MXUS 3000 Hub Motor - V1 V2 V3

[madin88]

you have forgot to half battery and controller Ohms on the 3t setup. thats at least one reason that 6T is faster (less voltage sag)
i always set these values to zero

 

[macribs]

you have forgot to half battery and controller Ohms on the 3t setup. thats at least one reason that 6T is faster (less voltage sag)
i always set these values to zero

Zero Ohm and superconductor? :wink: /joke

To get a result as close to real life as possible in the simulator, I think Ohm is to needed to be accurate to give best result, yes? Setting the value to zero seems it will give to good to be true result.

Conclusion: While a 3T MXUS may be able to run fine in a 28" (Fat) Tire without overheating, it is NOT as efficient as a 6T with twice the voltage and 1/2 the current.

I think that one thing to consider is that for most users there often is not really an option to double the voltage, as many controllers tops out at 20s. I mean if you get powerful motors like this you have plan to abuse it and have fun, right?

So for many users they need to decide on controller and after that they must keep voltage within limits of the controller. Even though many controllers has high current like 200-400A it is hard to volt past 20s. Ideally we should probably use a >24s setup or more but that is expensive.

While many do not aim for 60 mph top speed, I am sure most of those who consider these motors would like at least 40 mph. But acceleration and climbing with the same voltage and wheel would be better in a 4T or 5T then with a 3T. Less top speed but quicker.

Another thing to consider is where can you remove/stand heat the best, heat in the controller or heat in the motor.

I think that give the motor the best condition to work in, smallest wheel OD. Enough voltage to be efficient or within controller limit. And then crank the current when needed by OVS.

 

[John in CR]

If two differently wound motors have the same total number and size strands on the teeth, the differences that arise are only from the phase wire terminations in the motor outward. In terms of capabilities and efficiency they're the same motor with the same amount of copper and same magnetic circuit, so they make the same amount of torque at the same rpm creating the same amount of heat. Through the use of his simulator, Justin demonstrated exactly that on previous occasion.

 

[madin88]

i believe the reason why 3T motor is less efficient compared to all other, higher wound types is the losses in the thin phase wires come into play.
on 4T and above winds the losses are negligible compared to losses in the motor, but on 3T the phase wire losses are much higher (if we talk about same torque output).
P loss = I² x R

 

[Rix]

Here are two different simulations of the MXUS 45mm Motors:

The first simulation is a MXUS 4504 (3T or 12Kv) winding in a 28" Tire, with a 36V battery and an 80A Controller.
The second simulation is a MXUS 4506 (6T or 6Kv) winding in the same 28" tire, but with twice the voltage and 1/2 the current.
All other parameters are identical.
In therory, the Myth says that these should be identical performing systems.


You will notice that the 6T winding has a higher max speed than the 3T, so if I reduce the throttle down to 91% on the 6T to match the max speed of the 3T set-up, I get the following:



And here are both 3T and 6T windings overlaid:


Conclusion: While a 3T MXUS may be able to run fine in a 28" (Fat) Tire without overheating, it is NOT as efficient as a 6T with twice the voltage and 1/2 the current.

Thanks for posting TeslaNV, Justin's simulator also tell me that most likely total copper fill on the 6T has got to be at least a little more than on the 3T which is why the NM Torque data isn't closer then that. Without inputting this into Justin's Simulator, I am betting the gap in efficiency would move a little closer together between the 3T and 6T if say the tire size was reduced to 24". For my own curiosity, I think I will check it out.

 

[madin88]

Thanks for posting TeslaNV, Justin's simulator also tell me that most likely total copper fill on the 6T has got to be at least a little more than on the 3T which is why the NM Torque data isn't closer then that.

3Tx20 has same copper fill as 6Tx10 - only losses between connections inside the motor are a tiny bit higher.
IMO the real reason for its lower efficiency is that in the simulation phase wire losses are included in total efficiency. thats the reason why 3T has less top end -> because of its higher amp need, the voltage drop from controller to motor is much higher and therefore torque also is lower

 

[Rix]

Thanks for posting TeslaNV, Justin's simulator also tell me that most likely total copper fill on the 6T has got to be at least a little more than on the 3T which is why the NM Torque data isn't closer then that.

3Tx20 has same copper fill as 6Tx10 - only losses between connections inside the motor are a tiny bit higher.
IMO the real reason for its lower efficiency is that in the simulation phase wire losses are included in total efficiency. thats the reason why 3T has less top end -> because of its higher amp need, the voltage drop from controller to motor is much higher and therefore torque also is lower

I did not know that, thanks for the correction. I didn't consider that, but that makes sense.

 

[teslanv]

you have forgot to half battery and controller Ohms on the 3t setup. thats at least one reason that 6T is faster (less voltage sag)
i always set these values to zero

Yes, in theory, for truly equal performance between systems, you would need to reduce the system resistance in half. Easy to do with the simulator, by selecting 1/2 the values. Much less easy to do in practice. It requires double the ampacity of the battery and phase wires and connections, as well as all the components in the controller's power stage. This is all glossed over in the theory of the myth discussion, but it is a reality that we must accommodate for when configuring complete systems with off-the-shelf and non-modified components.

 

[John in CR]

In practice the speed wind wins, because you don't end up going to double the phase amps and begin to appreciate the attraction of smooth starts without doing so by artificial means that end up coming back to kill on hills. I've been using speed wind 40mm stator motors since 2008, and I live in a mountainous country and push a much higher than typical load before considering I often carry a passenger. None of those have temp sensors, and most are still sealed, and all have been bogged down on grades too steep, yet I've never burned one up. Those are set up for a top speed right around 60mph whether it's with a moto wheel with a 20" OD or 24" OD. While that's still just anecdotal evidence it trumps anything the slow wind camp can counter with, simply because it's in direct opposition to the myth.

As far as the sims go, with Justin proving through sims that the motors are identical regardless of winding why go any further? Without understanding I'll always just take Justin, Miles, LiveForPhysics, etc. word for it without question. Then I'll go back and figure out why they are correct. LFP has opted in favor of speed wind motors to reduce BMS costs, and he looks at controllers as simply buck convertors so pack voltage doesn't even matter. I opt for them because controller voltage limitations make the speed winds capable of more power. Justin and Miles look at motors from the standpoint of electric assist, so to them the motors are identical and using what is convenient in terms of equipment you already possess or staying with the common 36V/48V options.

 

[Rix]

In practice the speed wind wins, because you don't end up going to double the phase amps and begin to appreciate the attraction of smooth starts without doing so by artificial means that end up coming back to kill on hills. I've been using speed wind 40mm stator motors since 2008, and I live in a mountainous country and push a much higher than typical load before considering I often carry a passenger. None of those have temp sensors, and most are still sealed, and all have been bogged down on grades too steep, yet I've never burned one up. Those are set up for a top speed right around 60mph whether it's with a moto wheel with a 20" OD or 24" OD. While that's still just anecdotal evidence it trumps anything the slow wind camp can counter with, simply because it's in direct opposition to the myth.

As far as the sims go, with Justin proving through sims that the motors are identical regardless of winding why go any further? Without understanding I'll always just take Justin, Miles, LiveForPhysics, etc. word for it without question. Then I'll go back and figure out why they are correct. LFP has opted in favor of speed wind motors to reduce BMS costs, and he looks at controllers as simply buck convertors so pack voltage doesn't even matter. I opt for them because controller voltage limitations make the speed winds capable of more power. Justin and Miles look at motors from the standpoint of electric assist, so to them the motors are identical and using what is convenient in terms of equipment you already possess or staying with the common 36V/48V options.

John, just curious, but are you getting 60MPH out of a 48v set up? I am not being a smart a$$, I sincerely want to know what you got going on that's the case. I am getting ready to start another build soon. I will be running the MAXE on 16S with the MXUS 4T and I am figuring with OVS max @ 7, I should break 50MPH. Even though everyone is free to run as many volts as their hearts desire, I agree with you about motors with lower turns and less volts.

 

[Samd]

I have to admit its what initially attracted me to the mxus. The thought of inexpensive controllers running on lower voltages, and a couple of commoditised 48v batteries in parallel to handle the ampacity. Cheaper system overall.
Was surprised then when people started mating them up with dearer components such as the Max-e , although I totally get that its for a high end build in that case.

 

[macribs]

@Rix I might be 2 drunk to understand this, but I always thought John in CR was a high voltage man? I've seen several posts where he runs way more then 100v. Does he have a new build that is running 48v? Oh well 1 in the morning and my glass i almost empty. Time for bed, I will check thread tomorrow with a heavy head and fools remorse

Cherioo all you bastards!

 

[teslanv]

Without understanding I'll always just take Justin, Miles, LiveForPhysics, etc. word for it without question.

Justin, Miles and LFP are smart guys, no argument there. But I don't take everything they say as gospel. Only as a starting point to extend my understanding.

John, you generally run a smaller diameter tire with those high speed winds, if I'm not mistaken.

I do as well, on my "fast" Ebikes. In fact the next race bike in my queue will be a 15Kv QS motor with a high-power sine wave controller. I fully appreciate the benefits of high Kv motors.

OTOH, with respect to slower speed bikes (under 35 mph) where larger tires are desired (such as a Fat Bike), a slow wind (high Kt) motor makes sense because the controller can be of lower spec and low cost, even voltage up to 18S are reasonably safe and the BMS (if present) is not as complex or as costly as you suggest.

 

[markz]

OK I've been playing around with the simulator, 3T compared to 6T.
I see how the torque line can match, upping the controller amps and changing the diameter of the wheel. That makes a lot of sense now.

However I have a fixed controller, and a fixed motor (fixed = factors you cant change), and the only factors I can change are the battery and wheel. Which is my case.
The battery I can have increased voltage to increase speed. Increase amps to increase torque, I guess that would be on the phase, and changed in the controller. Is anyone putting 242A to the phase? Can the Lyen 18fet handle 242A on the phase for 60seconds?

The wheel size difference does not show up on the graph in terms of torque, but the speed changes I see.
Efficiency seems to be 6% difference, until 28km/h when it reaches 10% diff. The higher eff is 6T.

This efficiency leads me to think the 6T is better then the 3T, but the above quote prooves me wrong.

What size tire would you prefer and what top speed are you shooting for?

A Smaller wheel will result in greater acceleration and climbing ability, but a larger wheel will generally provide for a better ride experience. A higher Kv motor (3T) will be more efficient in a small diameter tire and faster overall, while a 6T motor can handle larger tires like a fat bike tire much better without overheating, and provide greater overall torque and require less current to do so.

That graph is the default 40A setting compared to the 65A the 18fet is suppose to have. There is lots of torque difference from the amps.
The max speed did not change (voltage), I felt 60kph, was way to fast for me. It was fun, I admit. I think 50kph max would be good for street riding.
There is a 30N-m difference at 15kph, but if I could rock it up a short 12%-16% hill at ~20kph I'd be happy, from a 15-20kph cruising speed, with a speed-up to the base of the hill run of about 30kph. Then

So once I put a smaller diameter wheel on my 4T, I will be able to climb hills better. . Just not from a stand still, like a 6T with its higher torque at the lower end of speed.
On my 26" I did feel my 18fet get kinda warm.

This whole different tooth count issue, is like a teeter totter, you lower one, up another to get the same effect of a different tooth count motor.
The issue then comes down to, building around whatever you have. You have "Fixed items" that are already bought, and "Variable items" that you need to buy in order to complete your eBike. In my case I have a fixed motor 4T, and a "semi-fixed" controller 72V 65A 18fet (because I can change the internals for different volts and amps - not to sure if I really want to be doing that though). I've heard from other es members that thet is p 18feerfectly suited for the 4T.

 

[Rix]

@Rix I might be 2 drunk to understand this, but I always thought John in CR was a high voltage man? I've seen several posts where he runs way more then 100v. Does he have a new build that is running 48v? Oh well 1 in the morning and my glass i almost empty. Time for bed, I will check thread tomorrow with a heavy head and fools remorse

Cherioo all you bastards!

Well I am not drunk....yet, got a few hours to go. I don't know if John in CR is a low volt or high volt kind of guy, I was going off his post about 48 volts and 60MPH. I may be misunderstanding what I am reading, because I have consumed any adult beverages yet.

 

[Rix]

I have to admit its what initially attracted me to the mxus. The thought of inexpensive controllers running on lower voltages, and a couple of commoditised 48v batteries in parallel to handle the ampacity. Cheaper system overall.
Was surprised then when people started mating them up with dearer components such as the Max-e , although I totally get that its for a high end build in that case.

Funny you say that, I originally wasn't going with the MXUS, until Allex mounted one for testing on his Bomber and acceleration was better than the 5403. That changed my mind. If you look at the simulator, the MXUS 4t is really close to performance of the TC4080, and only a pound heavier, and cheaper. Yep, going to be quick.

 

[madin88]

John, just curious, but are you getting 60MPH out of a 48v set up? I am not being a smart a$$, I sincerely want to know what you got going on that's the case. I am getting ready to start another build soon. I will be running the MAXE on 16S with the MXUS 4T and I am figuring with OVS max @ 7, I should break 50MPH. Even though everyone is free to run as many volts as their hearts desire, I agree with you about motors with lower turns and less volts.

Instead of using OVS7 to achieve the top end you like to have, it would be better to take the 3T motor.
Or go with 20s instead of 16 and use lower OVS level. This would be MUCH more efficient.

btw: the coming days i will assemble my heavily modded 3T motor. the mods in detail:

- custom axle (will offer them also for sale)
- 8mm² phase wires
- shilded extra cable for halls
- entire inside painted black (justin has proven that this would improve cooling / heat absorption by approx 20%)
- aluminum heat sinks attached to the inner side of covers to increase surface area
- 2 blower wheels from pc fan also attached to the sidecovers for good air convection

the goal:
i want to have a motor with same (or more ) continuous power than the Cromotor, but with the benefit of 3-4kg less unsprung weight for a more comfortable riding and for less physical effort if i need to carry the bike upstairs into my flat

 

[chucho]

John, just curious, but are you getting 60MPH out of a 48v set up? I am not being a smart a$$, I sincerely want to know what you got going on that's the case. I am getting ready to start another build soon. I will be running the MAXE on 16S with the MXUS 4T and I am figuring with OVS max @ 7, I should break 50MPH. Even though everyone is free to run as many volts as their hearts desire, I agree with you about motors with lower turns and less volts.

Instead of using OVS7 to achieve the top end you like to have, it would be better to take the 3T motor.
Or go with 20s instead of 16 and use lower OVS level. This would be MUCH more efficient.

btw: the coming days i will assemble my heavily modded 3T motor. the mods in detail:

- custom axle (will offer them also for sale)
- 8mm² phase wires
- shilded extra cable for halls
- entire inside painted black (justin has proven that this would improve cooling / heat absorption by approx 20%)
- aluminum heat sinks attached to the inner side of covers to increase surface area
- 2 blower wheels from pc fan also attached to the sidecovers for good air convection

the goal:
i want to have a motor with same (or more ) continuous power than the Cromotor, but with the benefit of 3-4kg less unsprung weight for a more comfortable riding and for less physical effort if i need to carry the bike upstairs into my flat

Any special paint for the black paint? are you painting inner side covers or everything? are ussing any primer to paint the aluminium before the black paint?

 

[John in CR]

Without understanding I'll always just take Justin, Miles, LiveForPhysics, etc. word for it without question.

Justin, Miles and LFP are smart guys, no argument there. But I don't take everything they say as gospel. Only as a starting point to extend my understanding.

When they say the same thing on a subject, if you disagree you should figure out where your misunderstanding is.

John, you generally run a smaller diameter tire with those high speed winds, if I'm not mistaken.

I will always run the smallest tire I can live with regardless of the winding, because a smaller tire is the one sure route to greater overall efficiency or greater performance for any given model of motor. Changes in winding (assuming equal copper fill) accomplishes neither.

OTOH, with respect to slower speed bikes (under 35 mph) where larger tires are desired (such as a Fat Bike), a slow wind (high Kt) motor makes sense because the controller can be of lower spec and low cost, even voltage up to 18S are reasonably safe and the BMS (if present) is not as complex or as costly as you suggest.

Higher Kv wind motors do slow just fine, in fact equally as well as low Kv motors. You've got to let go of the myth, because the different ways you try to word it misleads your customers. My purpose for posting is to prevent you from creating a whole new generation myth propagators. Of course lower voltage BMS's are less complex, but that's really LFP's argument for the highest Kv motors possible, since I know little about them because I am the BMS on my bikes. On the subject of cost, price/performance is my primary criteria, and you can't put low cost and controllers in the same sentence and keep a straight face.

It's great that you're bringing in a good size motor to sell at a price that saves people money by avoiding air shipment from China, and you include more technical details than anyone, which is commendable. Why muck it up with false statements about low Kv motors being better in big wheels or more efficient on hills. Once you get a full understanding, then you can get down to just 2 different windings, one for those who really only want low speed and the 3T is too fast in a full size wheel even at only 36V. That will simplify inventory as well as dealings with the supplier.

Comparing the phase-to-phase resistance for the 3T and 6T, I may have found the reason for differences showing up in the simulator. You should remeasure to be sure those figures are accurate, because if they are then the 3T doesn't have near the copper fill it should. The 6T should have a bit over 4 times the resistance, because it's double the length and 10 strands vs 21 strands. It could be that the copper is there, but not all 21 strands are electrically joined. I don't know how the factories do that part but I've had trouble getting all the strands well connected at both ends when using magnet wire to maximise copper through the axle. Unless I'm missing something there are only 3 possible explanations for 220mOhms for the 6x10 and 70mOhms for the 3x21:
1. Measurement error
2. 21 are there but some aren't connected
3. Not all 21 strands are there

Hopefully it was just a measurement error or an isolated instance of a poor phase termination, but it definitely warrants follow up. The 3T resistance seems high by 10-15mOhms, which doesn't seem like much, but it can easily be hundreds of watts of extra heat. That would throw the results for the 3T out of whack.

 

[teslanv]

I believe the difference is explained by the 2.5mm2 phase wire's 50cm length before it reaches the windings. When I made the phase wires shorter (they were ~80cm long), the phase resistance was notably reduced.
On the 3T motor I upgraded the phase wires on, the Phase resistance is .059 Ohms.

 

[madin88]

Comparing the phase-to-phase resistance for the 3T and 6T, I may have found the reason for differences showing up in the simulator. You should remeasure to be sure those figures are accurate, because if they are then the 3T doesn't have near the copper fill it should. The 6T should have a bit over 4 times the resistance, because it's double the length and 10 strands vs 21 strands. It could be that the copper is there, but not all 21 strands are electrically joined. I don't know how the factories do that part but I've had trouble getting all the strands well connected at both ends when using magnet wire to maximise copper through the axle. Unless I'm missing something there are only 3 possible explanations for 220mOhms for the 6x10 and 70mOhms for the 3x21:
1. Measurement error
2. 21 are there but some aren't connected
3. Not all 21 strands are there

John, please dont be angry with me, but you should READ and not only write.
It was mentioned that it is quite sure most of 3T motors shipped does not have 21 strands. I have called the factory because of this and they said its very hard for the workers to fit 21 strands so they mainly did only 20 strands.
Also it was said that justin does the tests with stock phase wires. They are about 1m long (at least on my motors) and have 2,6mm²
Guys, now look how the losses grow with the amps:

at 50A: 0,75V drop and 37W
at 100A: 1,5V drop and 150W
at 200A: 3V drop and 600W

with my 8mm² wires:

at 50A: 0,28V ddrop and 14W
at 100A: 0,57V drop and 57W
at 200A: 1,13V drop and 226W

Yes there could be a problem with the wye joint, but i don't think so.

I must say i don't see anything wrong about what teslanv says.

- if you do not want to go fast (as ex fat bike) than a slower motor will offer more system efficiency -> right
- the controller can be of lower cost -> right
- generally higher system efficinecy (less amps -> lower losses over stock phase wires and inside controller, higher inductance -> also better for the controller)
- a wee bit less copper losses inside the motor even if copper fill is the same

what should be misleading here? i would say the same to my customers

 

[markz]

madin88 - Wow you must be heating up your motor a lot.

 

[John in CR]

@Rix I might be 2 drunk to understand this, but I always thought John in CR was a high voltage man? I've seen several posts where he runs way more then 100v. Does he have a new build that is running 48v? Oh well 1 in the morning and my glass i almost empty. Time for bed, I will check thread tomorrow with a heavy head and fools remorse ...

Except for my SuperV, which I run at 30s (111v nominal) for going on 2 years, all of my other ebikes are and have been 74V nominal (20s lithium polymer or 23s lifepo4) since 2008.

While I could probably figure out a way to run a 26-29" wheel and reach 60mph on 48V, I'd never do it because I'd take a big hit to overall efficiency trying to get to the acceleration I've come to expect.

 

[litespeed]

Well for the second time it appears I lost my halls in my 6T. I was doing some full throttle runs and pulling my son up our slight hill on his skate board. Did it easily with me, the bike and him. 205 lbs me, 120 lbs bike and 165 lbs him. Temp on the outside never exceeded 120 degrees but not sure what that translates to on the inside. I'm ordering fans, 10 more genuine Honeywell SS41 halls and cutting holes for forced cooling CowardlyDuck style. Amps max at 70 and phase is turned down to 100 so I'm not really pushing it that hard...or so I believe anyway.

Not sure what is up with the halls sensors though. Spec sheet says good to 150 Celsius, surly there is no way I reached that with a 120 degrees or 49 degrees Celsius on the outside covers? Anyway I pulled the hub apart so I could measure to see what size fans I can fit in there. Looks like 6--25mm square fans.

I think I just need to order the QS205 or QS273 motor and deal with the larger mass.

Tom

 

[teslanv]

Well for the second time it appears I lost my halls in my 6T. I was doing some full throttle runs and pulling my son up our slight hill on his skate board. Did it easily with me, the bike and him. 205 lbs me, 120 lbs bike and 165 lbs him. Temp on the outside never exceeded 120 degrees but not sure what that translates to on the inside. I'm ordering fans, 10 more genuine Honeywell SS41 halls and cutting holes for forced cooling CowardlyDuck style. Amps max at 70 and phase is turned down to 100 so I'm not really pushing it that hard...or so I believe anyway.

Not sure what is up with the halls sensors though. Spec sheet says good to 150 Celsius, surly there is no way I reached that with a 120 degrees or 49 degrees Celsius on the outside covers? Anyway I pulled the hub apart so I could measure to see what size fans I can fit in there. Looks like 6--25mm square fans.

I think I just need to order the QS205 or QS273 motor and deal with the larger mass.

Tom

The 6T will overheat pretty quick at 100A phase. It is only rated to handle 30 Phase Amps continuously.