Doubling up a mini hub Farfle style??!

[Whiplash]

I have been really trying to find the best match of performance/size/weight for my new bike. To be honest that is why I'm dragging my feet a bit. I really want a nice compact but fairly powerful motor to mount to the swingarm of my bike small in diameter so it looks right from the side profile. The MAC is close but really is too big to be honest. I want to get close to 2500- 3K watts of power and I was wondering if I used a DD mini hub and doubled it up like Farfle did with the magic pie motor and re wound for a fairly high KV so I could get it spinning fast then gear it down on say 12s if I could make this work? I think I could keep the width down where it won't interfere with pedaling and get the nice little mini powerhouse I want. Any opinions? I'm just thinking this could be the ticket for me as the motors are really cheap so getting two is still less than any other motor...

Nobody has gone this so I figure its worth investigation??...


Maybe farfle had the right idea just different application..

 

[neptronix]

You can go dual pie, but it will be wide as the MAC if not more..
How 'bout a john in CR motor?
For lightness, how 'bout an Astro?

Wish i had 2kW MAC lawnmower motor results for you.. it's much narrower in the lawnmower version after the shaft is cut down some.

 

[Whiplash]

Yeah a dual pie was not the intent here. I was talking about the mini front wheel motors that will take around 750 watts typically. I don't want to run more than one stage of reduction either, I was thinking of joining two of those with a rewind and bigger phase wires/cooling mods to get to around 2K watts THROUGH THE GEARS. I think this would be a great compact setup for a mid powered bike and still handle decent power. I just want something small in diameter and around 5" wide when mounted that can take 1500-2000 watts semi continuous or maybe a bit more for bursts. There has to be a way!

 

[spinningmagnets]

I've recently been looking at direct-drive smaller motors, similar to the old Crystalyte 408. Hard to get internal guts info, and I don't really want to buy ten different motors just to be able to write up an index. Here's a couple of suppliers if you want to dig through them:

http://www.conhismotor.com/ProductShow.asp?id=284

http://www.uumotor.com/12-inch-500w-gearless-hub-motor-direct-drive-regen-braking.html

 

[Whiplash]

The second one seems interesting. Wonder what it'll really handle power wise?

 

[Whiplash]

What do you think of this little guy with a double wide stator and vented or oil cooled?? Think it could do over 2K? It would come in at 5-1/4" wide cover to cover so it could work! So with double the stator it should do double the rated torque with the same amps right? That puts it at 30Nm at the RATED input. So if we figure it at a safe (I would think) 750 watts per stator that's 1500 watts with hopefully more capable being vented or oil cooled. Do you think it could do that kind of power? I imagine my wind COULD add copper fill since I'll take my time versus the factory and its 10 second winds!

If I'm way out in left field stop me, but I really like this idea due to the very compact motor once the spoke flange is trimmed off for the mid drive setup.


http://www.conhismotor.com/ProductShow.asp?id=84

 

[Whiplash]

Additionally the above motor's end turn losses would be less as well! I am thinking this could be the setup for me!

 

[Whiplash]

Anyone know anything about this little guy? It looks exactly like the conhismotor I posted above and THEY claim it'll handle 30A @ 48v!! If that's true, this thing double wide could be my holy grail!! ANYONE have experience with these people? Do they know what they are talking about??

http://www.leafbike.com/products/e-bike-hub-motor/gearless-20-24-26-700c-28-inch/26-inch-36v-250w-rear-brushless-motor-wheel-943.html

 

[WhatcomRider]

Anyone know anything about this little guy? It looks exactly like the conhismotor I posted above and THEY claim it'll handle 30A @ 48v!! If that's true, this thing double wide could be my holy grail!! ANYONE have experience with these people? Do they know what they are talking about??

http://www.leafbike.com/products/e-bike-hub-motor/gearless-20-24-26-700c-28-inch/26-inch-36v-250w-rear-brushless-motor-wheel-943.html

Whiplash, did you watch the video that is linked on that page? My impression is that it is exceptionally quiet and smooth running. It could be just the ticket. I encourage you to email them with a numbered list of questions. The quality of their answers should give you a pretty good idea if they know what they are talking about.

 

[Whiplash]

Good point, I think I will. If it will in fact handle that kind of power even if its only for a few minutes at a time. Once I double it up I should be able to pull a solid 2500 watts if not more since it should be more efficient due to less end turn losses and hopefully better copper fill HOPEFULLY lol! I am pretty excited about this, I have been searching for a motor that can do this for a while now. And the fact that it does not have gears to strip means a simple temp probe inside will keep it reliable using the CA3. I think I'll try one and see how it does stock, that should be a good indicator... I mean its so cheap to just try!

 

[crossbreak]

The rotor is about 50mm thick, will have a hard time to place a 100mm wide rotor into your frame :? I'm keen to see this motor from the inside. Never opened one, since the side covers sit so tight. I got the old version without 6-hole disc mount, maybe the new version isn't that hard to open up. Once placed it into the frame for testing. Really a nice motor. You can push 1500Watt through it if you gear it fast. Now it's spoked in a 26" wheel. It runs 48V/30amps since years. Still runs great, barely gets warm. But not as silent as the Clyte HS-series. It's quite low efficiency at low rpm, just no comparison with a geared motor of the same size, have to run it fast, then it's a great one.

 

[Whiplash]

Thanks cross! I was hoping someone had real world experience with one! I am putting this in the swingarm just behind the BB in the swingarm. I can fit about 150mm max width, so hopefully after I trim off the extra material on one side of each of the magnet rings, I can press them together using a piece of large tubing as the joint along with some devcon epoxy for good measure. It'll be tricky to get the magnets aligned during the joining of both halves but I'm sure it can be done. If you say it'll handle 1500 watts then I have FINALLY found the recipe! 3000 watt capable silent AND small diameter!! I'm going to go for it as soon as I get the cash! Best part is, its only about $350 shipped for the TWO motors direct from conhismotor!

I wonder how hard it would be to just stack the two stators on a new shaft and forget re winding it? Could that work?? Obviously I would lose the end turn gains but if what you said is true it may not matter too much. I would just have to get the two stators lined up perfectly to each other right? Then I could still use one controller and just parallel all the wires....HHHMMMMMMmmmm...

 

[Whiplash]

Hey Cross, do you think it would handle more than 1500 if I did some cooling mods and ran it at say 72ish volts? I'm thinking 18s Lipo should do it well! Maybe if I run it up there I can get away without doubling it??

 

[John in CR]

The easy and sure way, and capable of far more later with higher voltage and cooling mods:


Any smaller and you need higher rpm, which generally gets far noisier. Series/parallel switching of the windings makes thru the gears unnecessary if you want speed and still climb a vertical wall. Better build quality is non-existent, and better efficiency is hard to find which means no heat worries.

 

[Whiplash]

Yes I agree your motor is far superior but for half the price of yours, if I can get 3000 watts in a package 127mm in diameter or less, and likely lighter than yours as well I just have to try it...

 

[flathill]

Just remember for radial flux hub motors

Double the width = double torque (linear finction)

But double the diameter = quadruple torque (square function)

Overall cubic function for torque

 

[Whiplash]

Yes that makes sense. The motor makes 15nm of torque in stock form with stock amps (18-20). If I am running 30A+ I should see around 22.5Nm in stock form. Then I double that figure for my double wide motor and that gives me around 45Nm. So it should be really powerful for a bike through the gears since I should have a gear ratio of about 2.75 in low gear I'll see about 123Nm at the wheel in a bike that weighs less than 100#. That's 91lb.ft. of torque in US numbers, that's a LOT! I have to believe that is enough for me.

Anybody know how much torque the MAC motor makes at 30A 12s lipo? I could use that to compare the two motors to know for sure if this one will do what I want since I already have that one working on my other bike mid drive....

Thanks!

 

[sabongi]

check ebikes.ca/simulator and choose bmc_v2 trq motor!

 

[Whiplash]

Its looking like the MAC I have is capable of around 50Nm at 30 A but I don't get as much reduction with that motor as I do in this new design. With my gearing I should be seeing about 80lb.ft. at the wheel so the little motor due to higher rpm and more reduction nets about 10 more lbs of torque at the wheel in low gear. This is assuming equal wattage input but the small motor can take more power than my MAC can. 1500 watts will kill bearings on the Mac if overdriven for long in the taller gears. I have done it..

 

[MitchJi]

Hi Whiplash,

This is assuming equal wattage input but the small motor can take more power than my MAC can. 1500 watts will kill bearings on the Mac if overdriven for long in the taller gears. I have done it..

Why not disable the clutch and mount a FW on the output shaft?

Yes I agree your motor is far superior but for half the price of yours, if I can get 3000 watts in a package 127mm in diameter or less......

How much do you bill for your labor?

 

[Whiplash]

Well actually it kills the bearings on the planetary gears not the clutch. Plays it really is too big of diameter for where I want yo put it. It'll work but not have the look I want. As for my labor, I usually don't bill myself lol.. I know your point though...