12" Rear hub motor

[AviG70]

I'm starting a new electric stand scooter build that requires a 12" rear hub motor, the scooter will need to run at about 25-30 mph on that motor, if I'm not mistaken that's 840 RPM.

30 mph = 30 X 5280 /60 = 2640 Feet per minute.
A 12" diameter wheel has (12"(=1ft)/2 X Pi X 2) 37.7" of circumference, that's Pi feet of circumference.
So 2640 / Pi = 840 RPM

What would be the motor wattage needed to reach such speeds?
I also need it to be pretty light, I aim at a target weight of no more then 40 lb for the whole thing including front and rear suspension so about 9-10 lb weight more or less is left for the motor, is that doable?
I have not yet succeeded in locating such a motor so I thought one of you guys may help pointing me in the right direction.

Thank you

 

[ian.mich]

I'm starting a new electric stand scooter build that requires a 12" rear hub motor, the scooter will need to run at about 25-30 mph on that motor, if I'm not mistaken that's 840 RPM.

30 mph = 30 X 5280 /60 = 2640 Feet per minute.
A 12" diameter wheel has (12"(=1ft)/2 X Pi X 2) 37.7" of circumference, that's Pi feet of circumference.
So 2640 / Pi = 840 RPM

What would be the motor wattage needed to reach such speeds?
I also need it to be pretty light, I aim at a target weight of no more then 40 lb for the whole thing including front and rear suspension so about 9-10 lb weight more or less is left for the motor, is that doable?
I have not yet succeeded in locating such a motor so I thought one of you guys may help pointing me in the right direction.

Thank you

http://www.leafmotor.com/hub-motors/12inch-electric-scooter-motor.html
You're looking at something like this hotrodded. They don't seem to have rpm info, likely have to buy it, install new phases, air cool, 72V controller and battery. you say your target is 40lb, including battery? I see this 12lb motor and >30lb bike with no battery? Likely want to read about lipo.

 

[Tommy L]

John in CR might have something for ya. He has sourced some strong hub motors, apparently.

Tommy L sends....

 

[John in CR]

Too strong for a stand up scooter. Plus the OP is looking for a motor to run a 12" OD stand up scooter wheel. Even our MiniMonster is too much for this application. I'm wondering if there might be small tire that could use the spoke flange of a common hubbies as the "rim". Goldenmotor.com has a cheap hubbie in the right size before, though I doubt it would go to 30mph. They now have a Smart Pie with an integrated rim and and built in controller that seems to even have the tire. Even the weight is near the OP's range at 5.5kg. Model# MW-12SP -- 12" Motor Wheel halfway down the page at http://goldenmotor.com/ . It even has a built in controller and is self-ventilating for cooler operation. The problem is even the 48V model looks like it's only 20mph. Another problem, at least for me, is the $295 price tag....plus shipping. Their high power 16" motor for $250 and can do thousands of watts is many times the motor and is only $250.

John

 

[AviG70]

Thank you guys for your kind advice,
Tommy, I just sent a PM to John, hope he may have some solution for me.

Ian, I believe it's doable at 40 lb more or less, may be even less. I'm not building this scooter based on an existing bike that weigh 30 lb to start with but rather I'll be making my own aluminum frame so I hope I'll hit that weight target. Thank you for the link to the 250W hub motor, but this is a very weak model, I'm not sure how many watts I need to go at 25-30 mph but it's much more then 250W.

 

[AviG70]

I'm still going through the sites trying to find the correct motor...

What do you think about one of these:
http://www.uumotor.com/10-inch-electric-motorcycle-hub-motor-800w-to-4000w.html
They seem to be spot on RPM wise.

Do you think that with some machine work they can be trimmed down to the desired weight for a bare hub motor?
Anyone know how are their motors quality wise?

 

[John in CR]

About the smallest tire you'll find to fit those 10" scooter/moto rims is 16". There is a motor on that site which looks to be exactly what you need. Note that their other 12" one is low efficiency junk, but this one looks good and at $155 http://www.uumotor.com/12-inch-500w-gearless-hub-motor-direct-drive-regen-braking.html

 

[Tommy L]

So sorry John in Cr........

To me, a Scooter is like a Vespa. I forgot that in this day and age, the Scooter is the stand up style unit.

Tommy L sends....

 

[AviG70]

About the smallest tire you'll find to fit those 10" scooter/moto rims is 16". There is a motor on that site which looks to be exactly what you need. Note that their other 12" one is low efficiency junk, but this one looks good and at $155 http://www.uumotor.com/12-inch-500w-gearless-hub-motor-direct-drive-regen-braking.html

Dear John,
What I mean to do with the 10" hub motors is machine off the 10" outer rim completely, remove the drum or the disk break completely, leave only enough to install a 6 bolt standard 160 mm bicycle disk, make the rest of the motor casing a little thinner, then weld a 12" bicycle rim to it and then install the desired tire. Tire+Rim+Tube =~ 1Kg so to start from a 14 Kg hub I'm not sure that's doable, even to start from the MiniMonster might weigh less in the end.

The 12 INCH 500W GEARLESS HUB MOTOR DIRECT DRIVE REGEN BRAKING you gave me a link to, it only goes to 20 mph and I need more. Have you worked with it personally? Do you know if they are the manufacturers of this motor? Will I be able to take the 36V 500W version and feed it 48V reliably to get that extra speed?

Do you know any company that would be making a custom BLDC hub motor design?
Avi

 

[John in CR]

Avi,

You can't go welding on a hubmotor shell. It will ruin the magnets. I can't help you if you don't listen. That other motor is perfect, but you didn't bother to look at the performance chart further down the page. On 36V and only 18A it's hitting it's max power at almost 600rpm. Feed it with 48V and a 30A controller and it's likely to put you exactly where you want to be with some headroom on speed, and a ton of acceleration.

Looking at the dimensional drawing, another route you could go is any smaller diameter hubbie with spoke flanges. Then get you 12" tire to know the diameter and bolt 2 rings, like giant washers, to the spoke flanges. Size the OD of those rings to match the size you need for them to form the rim for the tire you want, or even start with a rim and bolt the 2 halves to the spoke flanges in this manner with nice support from bolts that reach all the way across. I can't believe I haven't thought of this sooner, because it's perfect for some stuff I want to do for the kids.

John

About the smallest tire you'll find to fit those 10" scooter/moto rims is 16". There is a motor on that site which looks to be exactly what you need. Note that their other 12" one is low efficiency junk, but this one looks good and at $155 http://www.uumotor.com/12-inch-500w-gearless-hub-motor-direct-drive-regen-braking.html

Dear John,
What I mean to do with the 10" hub motors is machine off the 10" outer rim completely, remove the drum or the disk break completely, leave only enough to install a 6 bolt standard 160 mm bicycle disk, make the rest of the motor casing a little thinner, then weld a 12" bicycle rim to it and then install the desired tire. Tire+Rim+Tube =~ 1Kg so to start from a 14 Kg hub I'm not sure that's doable, even to start from the MiniMonster might weigh less in the end.

The 12 INCH 500W GEARLESS HUB MOTOR DIRECT DRIVE REGEN BRAKING you gave me a link to, it only goes to 20 mph and I need more. Have you worked with it personally? Do you know if they are the manufacturers of this motor? Will I be able to take the 36V 500W version and feed it 48V reliably to get that extra speed?

Do you know any company that would be making a custom BLDC hub motor design?
Avi

 

[AviG70]

Very sorry, I'm trying very hard to listen and learn... I read everything you write carefully and then read all the links you provide as well, including the performance chart, only after that if I have more questions then I reply to you so thank you for further clarifying this matter.

Regarding motor performance charts, I don't know the difference between P1 and P2?

Would you know of a good place to purchase this type of controller/kit?
Is there a complete solution for integrated controller/charger/BMS in one box?

I appreciate all your help

 

[John in CR]

That's power in and power output. Near the max rpm there is no load or very little load, so very little work is done and power output and efficiency are both low. Power is torque X rpm, so as the dyno starts to load it down, the motor makes more torque and power. They didn't include the full chart, where it continues to load it down and rpms drop and efficiency and power fall off at the other end of the spectrum.

i haven't seen a motor like that rigged for a standup scooter, and their price looks good, so why not buy from the source you found?

Let us know how it works out.

John