MP3 torque: Is it good or not?

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cwah   10 GW

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MP3 torque: Is it good or not?

Post by cwah » Feb 20 2012 6:35am

Hello there,

I was checking the motor specification for the Magic pie 3 on 16 inch wheel. I've found this data sheet:
Image
http://www.goldenmotor.com/magicpie/16i ... 20Data.pdf

It's only around 16-17 N.M at 20A. It's not huge I think compared to other motors.

The data sheet comes from 2009, so I'm not sure if the information are up to date or not (the new one is suppose to have 30% more torque).


If we compare this to the G209 motor at 3.5kg, the torque is quite similar:
Image
http://crystalyte.com/G%20series%2030KM.pdf

It's also around 16-17 N.M at 20A.


The only difference is that the MP3 is much more efficient than the much smaller motor. Several member have reported good torque from MP3, but actually it seems to be identical to a motor 2 times lighter.

So is it more torquy only because it's able to handle more amps without melting?
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Re: MP3 torque: Is it good or not?

Post by Scottyf » Feb 20 2012 8:10am

So is it more torquy only because it's able to handle more amps without melting?
YES

People put alot more than 20amps through a MP direct Drive hub. Most put double that to get it shifting.

Check out the geared hubbies. THese create much more torque at the same amperage.
Image

Still I thought it was high speed your after?
You'll have to loose some of that torque as a trade of for speed.
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cwah   10 GW

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Re: MP3 torque: Is it good or not?

Post by cwah » Feb 20 2012 9:04am

I only aim for 50 kph, but I've noticed in London I do a lot of stop and start. So maybe good torque at 40 kph would still be fine.

I was thinking that with Direct drive hub, what is great is the regen feature allowing to increase the distance. Especially on city with redlight everywhere.

Not completely sure what I'm after though :lol:
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Re: MP3 torque: Is it good or not?

Post by Scottyf » Feb 20 2012 11:02am

I think we've all noticed.
Pick one.

The magic Pie will be heavy. But fast.
Geared Motor - Lighter, more torque. Sheds heat slower - can't be overvolted as high.
(I'm running a geared motor up to 500rpm sensorless) which is a wind for 20mph in a 24 inch wheel. Apart from mines in a 28inch wheel.

I think you should aim for a smaller Direct Drive motor if speed is your game.
I don't think the geared variants can offer what your looking for in that small a wheel.

I think you'd be more than happy with a smaller direct drive and it will do what you like.
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cwah   10 GW

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Re: MP3 torque: Is it good or not?

Post by cwah » Feb 20 2012 1:08pm

I like speed... but I looooove torque. I'm hesitating about getting a huge DD such as a MP3 for good speed and torque and regen :D

I'm just afraid a small DD won't have enough torque.

This small mini hub motor I just purchased is going to melt if I use it at more than 10amps on it:
Image
http://www.conhismotor.com/ProductShow.asp?id=76
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Scottyf   100 W

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Re: MP3 torque: Is it good or not?

Post by Scottyf » Feb 20 2012 2:44pm

Why would it melt?
People run the geared small hubs at 20amp, they don't shed heat as well and work fine and there geared.

Have you tried?!?
Most rated motors will take at least 3 times what there rated for.
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Re: MP3 torque: Is it good or not?

Post by MadRhino » Feb 20 2012 3:51pm

cwah wrote:...
I was thinking that with Direct drive hub, what is great is the regen feature allowing to increase the distance. Especially on city with redlight everywhere...
What is great about regen is braking efficiency, it doesn't add significant range unless you have looong slopes where you can sacrifice downhill speed for continuous regen.
Make it fool-proof, and I will make a better fool.
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cwah   10 GW

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Re: MP3 torque: Is it good or not?

Post by cwah » Feb 20 2012 4:08pm

Scottyf wrote:Why would it melt?
People run the geared small hubs at 20amp, they don't shed heat as well and work fine and there geared.

Have you tried?!?
Most rated motors will take at least 3 times what there rated for.
I mean this motor is really inefficient from 10amps onward. I bet at 20amps it has around 30-40% efficiency and probably 20% efficiency at 30amps.

Unless I only use around 5 amps continuous, which is probably not enough to maintain a decent speed, it's going to be a very inefficient motor at more than 20mph.
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Re: MP3 torque: Is it good or not?

Post by neptronix » Feb 20 2012 4:22pm

Mp3 and mp2 are the same, in terms of the motor itself ( the controller is going to be different of course )

Frankly, in that spec sheet, they are not even pushing the motor at all. 35 volts and 22 amps, OH MY! someone could get hurt with all that power ;)



When I first hooked up 33a/57v power to it, it was already doing unintentional wheelies. This motor is super, super underrated.

The smaller direct drive motors are weak, IMHO, i owned one of that size and width ( mxus/9c/gm non-magic pie hub are generally the same ), and it sucked ( given the same wattage ) compared to my MAC and magic pie. Despite being a slower wind than the MAC 8T that i have, the acceleration / torque felt like i was running half power, in reality the copper gets so hot so quick that the resistance inside grows exponentially when you start to push the motor at all.

The smaller diameter DD hubs are an absolute dead end for performance.. they heat up rapidly on even on short 2000w-3000w bursts..

The secret of the magic pie's high torque is the diameter of the motor. I would put it right up against my MAC motor in terms of how much torque it can make. But it's not totally a fair comparison since my magic pie is in a 20" wheel and a much slower wind. You won't get the same performance as me in a 26" wheel, but it will be miles ahead of the smaller diameter DD motors.
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My first major build: 1.6kW 8T MAC motor on a Trek 4500.
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Re: MP3 torque: Is it good or not?

Post by cwah » Feb 20 2012 4:33pm

neptronix, at 30 amps do you mean the Magic pie 3 has more torque than any other motor? Because in the data sheet it doesn't seem so.
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Re: MP3 torque: Is it good or not?

Post by neptronix » Feb 20 2012 4:44pm

cwah wrote:Unless I only use around 5 amps continuous, which is probably not enough to maintain a decent speed, it's going to be a very inefficient motor at more than 20mph.
Which motor are you referring to? I get roughly the same efficiency as the MAC/BMC motors on my 20" magic pie doing 30mph. It never heats up even after extended use at 30-35mph ( using the 120% speed switch, which is super inefficient ) and 4000w bursts of power.
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
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Re: MP3 torque: Is it good or not?

Post by neptronix » Feb 20 2012 4:45pm

cwah wrote:neptronix, at 30 amps do you mean the Magic pie 3 has more torque than any other motor? Because in the data sheet it doesn't seem so.
No way, it wouldn't compare to something like the cromotor :)
But in a 20" wheel size, it is right up there with the crystalyte 53xx.
The advantage is the diameter of the motor.
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

cwah   10 GW

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Re: MP3 torque: Is it good or not?

Post by cwah » Feb 20 2012 4:49pm

neptronix wrote:
cwah wrote:Unless I only use around 5 amps continuous, which is probably not enough to maintain a decent speed, it's going to be a very inefficient motor at more than 20mph.
Which motor are you referring to? I get roughly the same efficiency as the MAC/BMC motors on my 20" magic pie doing 30mph. It never heats up even after extended use at 30-35mph ( using the 120% speed switch, which is super inefficient ) and 4000w bursts of power.
I'm refering to the mini DD hub from Conhismotor:
http://www.conhismotor.com/ProductShow.asp?id=85

Its peak efficiency is around 3-5 amps (78%), at 12amps it has 60% efficiency. The efficiency curve should be similar to the small DD G209: At 20 amps it has around 40% efficiency and at 23+ amps less than 20%.


This motor is very efficient at 15mph (around 6-7 amps), but for 30 mph, it's not very efficient
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Re: MP3 torque: Is it good or not?

Post by neptronix » Feb 20 2012 5:09pm

Oh totally forget that thing, that is the worst case scenario for direct druve hub motors ( small diameter, small windings/magnet, etc ).

It will most likely start heating up around 20-25mph and fully saturate at 30mph, lol.

4.7kg? that's heavier than a MAC/BMC motor, and probably handles about 1/2 the power or less.
I wouldn't recommend that motor to anyone.
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

cwah   10 GW

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Re: MP3 torque: Is it good or not?

Post by cwah » Feb 20 2012 5:41pm

The problem is that I have a 16" wheel. I talked to cell_man and he confirmed that the mac motor can't handle 30mph on 16" wheel. With the geared it would end up with 4000RPM and may result in stator loss. :(

Otherwise I'd have got the mac, but now it's more about alternative for my brompton :)
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Re: MP3 torque: Is it good or not?

Post by neptronix » Feb 20 2012 7:36pm

The magic pie can come in a 16" size.
Due the the non-standard size dropouts though, i think only the front motor would work.
But then your front fork probably can't handle that power..

Honestly, i would consider converting another bicycle.
<--- went through 4 different bikes before he found the perfect one. Luckily i bought them used..
"Love and compassion are necessities, not luxuries. Without them, humanity cannot survive." - Dalai Lama

My first major build: 1.6kW 8T MAC motor on a Trek 4500.
The new all-arounder: Leafmotor 1500w @ 4kW on a Turner O2 full suspension.
The monster scooter: 20" eZee on a Cannondale Semi Recumbent.
Whipper-snapper: ? on a lightweight BikeE Semi Recumbent

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Re: MP3 torque: Is it good or not?

Post by cwah » Feb 20 2012 7:50pm

That's fine for the rear dropout. It's only 110 mm wide but because it's steel I can extend it.

Then I'll add 2 strong torque arm and it should fly :lol:
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