MXUS 3000 Hub Motor - V1 V2 V3

[John in CR]

What is the advantage from the 0.35mm lamination over the 0.5mm lamination? Is the lamination material the same for both versions?

Below 1000rpm there won't be much difference, though if you're operating at the margins even 50 or 100W may be enough to make a significant temperature difference. If someone would take simple measurements for inclusion in Miles' motor spreadsheet, then we could easily calculate the difference at any rpm desired. Unfortunately people choose rely on purely anecdotal evidence for all the popular motors, so no one can make an even a reasonably educated guess at realistic controller settings. Wildly overstated claims just make things worse. eg Take Alex's claim above to push 400A into his Xlyte 5403. DoctorBass measured the phase-to-phase resistance of that motor to be right at 0.1 ohm. If you pump 400A thru one it will then generate 16kw of heat in the copper, which will increase to over 20kw of heat as the motor gets up to operating temperature. Anyone who believes that motor can withstand that for more than a very few seconds at a time I have some swampland to sell.

 

[teslanv]

If someone would take the simple measurements for inclusion in Miles' motor spreadsheet, then we could easily calculate the difference at any rpm desired.

I need to find a reliable way to measure milliohms. My Fluke DVM will only measure to 0.1 ohms.
I will have a 3T wind to test soon.

 

[hydro-one]

load up a phase with a known current and measure the voltage drop across the winding?

 

[Icewrench]

MXUS 5 turn Raw phase resistance numbers
1.69 amps
.287 volt drop
I`ll let someone else do the math.


Edit Yes this is a mxus 3000 v1
Thanks for the math lesson John

 

[Brake]

If someone would take the simple measurements for inclusion in Miles' motor spreadsheet, then we could easily calculate the difference at any rpm desired.

I need to find a reliable way to measure milliohms. My Fluke DVM will only measure to 0.1 ohms.
I will have a 3T wind to test soon.

Ooooooh I want one!!!!

 

[teslanv]

Bare motor, Bicycle or Moto Rim? 8)

 

[John in CR]

MXUS 5 turn Raw phase resistance numbers
1.69 amps
.287 volt drop
I`ll let someone else do the math.

Way to go Icewrench. Hopefully those with the other winds will follow suit.

Since I can do it, it must be nice and simple. Just use Ohm's Law Resistance = Voltage drop / current, so the phase-to-phase winding resistance is 0.170 ohm. Is that a V1 MXUS 3000?

If you're ready for the eye opener (at least it was for me), calculate copper losses (heat generated in the copper of the motor from it's resistance) for different current levels, and then you quickly see why people run into heat problems. That formula is Current Squared X phase-to-phase resistance. eg at 50A the heat generated is only 425W, but at 100A it is 1700W. Note that the current in question is phase current, which is higher than battery current in the lower half of the rpm range.

 

[John in CR]

Bare motor, Bicycle or Moto Rim? 8)

Those would be a consideration when measuring no-load current, not phase resistance. Ideally you want to measure no-load current with a bare motor, since the wind resistance of a spinning wheel will present some load and increase the no-load current. If done with a rim laced, then avoid high rpm. To best take advantage of Miles' effort, measure it at 2 different rpms. Measuring no-load current gives us the iron losses, because the copper losses are miniscule at such low current, and having 2 measurements at different rpms enables calculation of the fixed and variable portions, so we can predict heat losses in the iron and magnets at different rpm.

While the no-load current of a bare motor is best for Miles' motor spreadsheet, it's also good to know with rim and tire on for your own rig for comparison purposes. The aerodynamics will be different rolling down the road on your bike, but it will still give you a some idea of the power usage just to spin the wheel at a given speed.

It will be interesting to see the differences between the V1, V2, and V3 motors, and then guys will have hard info when ordering, as well as offer some guidance in controller settings.

 

[teslanv]

load up a phase with a known current and measure the voltage drop across the winding?

How to generate a known current? Still don't have a bench top Variable power supply, and any time I connect a charger/power supply, it shorts when I connect the leads to the phase wires...

 

[hydro-one]

use a lipo battery mabye a couple 18650 cells? should provide some current.

 

[Icewrench]

I use a 12 volt battery with a 1157 taillight bulb in line to an ampmeter to a phase lead and another phase lead back to the battery. Connect a voltmeter across the phase leads to read the volt drop.
Give the numbers to John as he is good with math.

 

[teslanv]

I use a 12 volt battery with a 1157 taillight bulb in line to an ampmeter to a phase lead and another phase lead back to the battery. Connect a voltmeter across the phase leads to read the volt drop.
Give the numbers to John as he is good with math.

OK. So basically add a resistor in series between the battery (or other power source) and the DMV (Ammeter). I think I get it now. I can do the math. :wink:

 

[teslanv]

OK. I found a 36W Halogen bulb and used that for a resistor.

I tested a MXUS 1000W motor (9X7 Wind) and came up with the following: (This is the motor I have upgraded the phase wires to 12AWG)

0.545V drop with 3.05A so that works out to 0.179 Ohms resistance in the phase to phase wires.

And using the formula (I^2) x Ohms, I get 447 Watts of waste heat at 50 Phase amps. That sounds about right for a 9X7T 1000W 9C Clone motor...

 

[hydro-one]

So basically add a resistor in series between the battery (or other power source) and the DMV (Ammeter)

the battery, dvm, and motor winding (and wire between, and connection interstatia) are all resistors.
another thing is once u understand this, u dont need fuses anymore. the wire is a fuse.

 

[Allex]

What is the advantage from the 0.35mm lamination over the 0.5mm lamination? Is the lamination material the same for both versions?

Below 1000rpm there won't be much difference, though if you're operating at the margins even 50 or 100W may be enough to make a significant temperature difference. If someone would take simple measurements for inclusion in Miles' motor spreadsheet, then we could easily calculate the difference at any rpm desired. Unfortunately people choose rely on purely anecdotal evidence for all the popular motors, so no one can make an even a reasonably educated guess at realistic controller settings. Wildly overstated claims just make things worse. eg Take Alex's claim above to push 400A into his Xlyte 5403. DoctorBass measured the phase-to-phase resistance of that motor to be right at 0.1 ohm. If you pump 400A thru one it will then generate 16kw of heat in the copper, which will increase to over 20kw of heat as the motor gets up to operating temperature. Anyone who believes that motor can withstand that for more than a very few seconds at a time I have some swampland to sell.

Yeah a motor gets up in temp pretty fast, look at my video with 400phase from 27°C to 45°C in just 10seconds. Does not make many runs like those to get it over 120°C
https://www.youtube.com/watch?v=MmuKBPBY67w#t=45

 

[madin88]

Measuring no-load current gives us the iron losses, because the copper losses are miniscule at such low current, and having 2 measurements at different rpms enables calculation of the fixed and variable portions, so we can predict heat losses in the iron and magnets at different rpm.

don't iron losses also rise if load increase (like copper losses) I have something about roughly 50% copper and 50% iron losses in mind..

 

[John in CR]

Measuring no-load current gives us the iron losses, because the copper losses are miniscule at such low current, and having 2 measurements at different rpms enables calculation of the fixed and variable portions, so we can predict heat losses in the iron and magnets at different rpm.

don't iron losses also rise if load increase (like copper losses) I have something about roughly 50% copper and 50% iron losses in mind..

The iron losses are strickly related to rpm and are incurred whether powered or not. Think of it as motor drag. It has too parts, eddy currents in the stator steel and magnets which increase mostly linearly with rpm (more specifically motor frequency, and hysteresis losses which are mostly fixed (I think it's what we commonly call the cogging force). That's why no-load current measurements are needed for at least 2 rpm, because it enables the fixed and variable components to be calculated.

The 50/50 part is peak efficiency for a given voltage (and duty cycle). ie peak efficiency is the point where copper losses equal iron losses. If the rpm goes higher then iron losses increase more than copper losses decrease, and adding more load to decrease rpm requires more current and copper losses increase by more than the iron losses decrease.

Our hubmotors are very underutilized in terms of rpm, so copper losses are dominant. This why it is always a big advantage to "volt up and gear down" with a hubmotor as long as you don't push the frequency too high. Lower pole count hubmotors have a significant advantage in this regard, because their alternating current operating frequency is proportionately lower. The reason high pole counts are common is because far less stator steel is required.

 

[madin88]

is it correct that:
iron losses are always the same (RPM related) and it does't matter if one motor put out 1 Nm or 100 Nm?
or: only copper losses rise under load (if current rise) and iron losses even now decrease due to RPM drop?

 

[John in CR]

is it correct that:
iron losses are always the same (RPM related) and it does't matter if one motor put out 1 Nm or 100 Nm?
or: only copper losses rise under load (if current rise) and iron losses even now decrease due to RPM drop?

Yes, the iron losses at a given rpm for a motor are fixed regardless of current flowing thru the copper. It may vary a little with temperature, but otherwise it's fixed even if you're just coasting at that rpm down a hill.

When you measure no-load current at WOT, then that's a measure of maximum iron losses. The rest of the losses other than a tiny bit of windage (air drag of the spinning rotor inside and out) and bearing friction, is virtually all from resistance in the copper.

The reason our motors have such low efficiency in the early stages of acceleration isn't because much changes on the loss side (it's primarily current squared times resistance), though some of the blame is higher phase currents at low rpm. It's because copper losses are so high compared to the power being produced, because power = torque X rpm, so power is very low.

 

[madin88]

thanks for your answer John. Its good there are people like you in the board with such good knowledge

if we are talking about improving hub motors, to enhance copper fill would help a lot for lowering heat at given torque output.
I have thought of rewinding one 3T MXUS by hand. Now it has about 4,2mm² cross section and i believe >6mm² should be possible without problems when using bigger gauge strands, BUT i have read something about "skin effect" which gets poorer the bigger each strand gets. Have to learn more about this and its effects..

 

[Punx0r]

Skin effect is thankfully irrelevant at the frequencies seen in any normal motor

 

[John in CR]

thanks for your answer John. Its good there are people like you in the board with such good knowledge

Thanks but the bits and pieces I know is thanks to others sharing on ES. The part I'm pretty good at, once I have a grasp of something, is putting it in plain English that anyone can understand.

 

[Seya]

Off topic a little but can anyone tell me if this motor has a spline or a threaded free wheel?

 

[teslanv]

Off topic a little but can anyone tell me if this motor has a spline or a threaded free wheel?

As are almost all HUb Motors, it is a threaded freewheel. The only Hub motor I am aware of that takes a cassette is the New Clyte Motors that Ebikes.ca sells.

 

[amberwolf]

THere are others, like the Fusin "1000W" in my review thread for it.

and someone recently had a thread asking about the MXUS one Grin sells.