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Small wheel hub motors

hubmotors

#1

I would like to consider the option of hub motors for my tiny board 24" with small wheels.
I think I can fit a 5030 or 5035 motor into the 59mm urethane wheel. With a dual drive system, a 6S battery and 25kmh max, I would need 100kv motors. Is it technically possible with the copper inside a 5030/5035 to get such a low kv?


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#2

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#3

I’m planning to build a custom hub motor. But before that, I need to be sure that’s technically possible…


#4

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#5

The fact that I’m considering a dual drive and a 25kmh max speed couldn’t cool down the motors?

Also boosted boars seems to use small motors in dual without heat issues…


#6

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#7

I’ve got some CAD files from a 40 and 50mm hub motor that was once in design if you’re interested.

The idea was scrapped because it simply wasn’t powerful enough in practice. If the stator is lengthened, it would probably work, but them its not truly a hub motor so much as a motor that has some thane attached to it.


#8

Yeah would love to see these CAD!

Were you considering dual drive at the time ?


#9

Yeah. You’d need 4x drive with these wheels. If you lengthen the stator (1.5-2x) you might be OK.


#10

http://shop.subsonicplanes.com/category.sc?categoryId=48

I’ve never seen these before!! And I looked a lot. Good stuff. Bit expensive.
Im selling the smallest hub motors I’ve seen for sale. Steelhubs.com. help me make these! It’s still experimental and progressing. I use a rare 4725 stator soon to be 4727.


#11

@Hummie I dunno, I know people like the 60-80mm wheel sizes, but I feel like big wheels are better for eBoards because the inertia will carry you further than a smaller diameter wheel will (plus smooth ride). Heat buildup is an issue you’ll have with making things smaller.

@brams Boosted can get away with small motors because of two features hub motors do not have:

  1. Gearing (meaning that the work to turn the wheel is distributed over several rotations, whereas a Hub Motor is a 1:1 direct drive).
  2. Cooling (Boosted Motors are exposed to the air without insulation. Hub Motors are heavily insulated by the wheels around them and warmer due to the amount of power needed to generate sufficient torque).

My opinion on the current state of community hub motors:
Before I bring out the haters and criticisms, they all bring different things to the table and are all pretty incredible. These notes compare Size/Heat/Shock + Sliding Durability based on what I’ve seen and what I would predict from the designs I’ve seen.

A) Hummie Hubs are small and dense but get a little on the warm side (still safe and good, and not really an issue unless considering thermal waste and the potential for a shorter life due to thermal wear-down on the windings/magnets). The bell + cap design should hold up against most sliding and shock damage.

B) Jacob’s Hubs are large in diameter and stay cool thanks to their decent ventilation (perform as well as Hummie’s for practical purposes. They generate less thermal waste but are probably more susceptible to mechanical wear [as in they’re tough, but I doubt they’d hold up against serious sliding]).

C) Carvon Hubs are essentially normal motors that are inline with the wheel and probably get as warm as a same size motor geared 1:1. They’re a different breed of hub motor from A or B. I have not read a recent comparison, but I would assume they stay relatively cool since they’re exposed and imagine that they’re mechanically susceptible to both sliding and shock by design, but I’ve heard nothing to support my imaginings.).


#12

Right now, of the three you listed, I would say the carvons are the least problematic. I say that cause I can’t do my normal route with hummies motors without having to stop multiple times to cool them down.

Because of the design on carvons, you can have the gear inside slip, and eat up the inside grooves design to hold the plastic gear ring in place. This only seems to be a problem if the board is jointed hard, and you don’t notice the ring slightly popped out and kep riding, as happened to me. I also had the hanger bend on the carvon, which is scary.

With hummies, mechanically, they are sound motors. Ridden many miles, with both the aluminum and now the steel. Temps are slightly better on the steel, but still too hot. My test is an 8 block test, which involves a 2 blocks of flat, 1 block of steep hill, followed by 1 block of flat, a block of slight up, 2 blocks down, 1 block flat, and 1 block up a slight hill again. on the aluminium, I was at 245 F, way too hot. The steel got to 198 F, which is still too hot. Part of my problem could be the difference between 10s and 12s. The other part is likely the low amp limits, due to the limits of the space cell. I did do a test climbing a hill with my laptop connected to the vesc. It shows me hitting do a constant 26-27 amps on one motor (the limit is set to 25). What this says to me is, I need a 12s that can pull more amps. Maybe 50 pounds is the difference, but hummie has very little heating issues, and generally doesn’t take breaks, while I find my self always taking breaks to let them cool.

Bottom line, I think a 4wd hub settup using hummies motors is the best option. Will get lots of torque, and will keep the motors much cooler (at least, that’s the hope). This is what I’m building right now, and am almost done with.


#13

Bottom line for me is that hub motors shouldn’t be too small. If you’re really keen on this, get in touch.

I predict that the smaller the hub motor, the thinner the wire gets. Therefore you’ll need more voltage and fewer amps (to keep cool for the same performance). The VESC can’t do 12s or more reliably and Jaanb’s motors are wound with 0.19mm wire.

You’ll need a higher voltage ESC and a higher voltage battery. The development costs for a hub motor hovers in the $2,000-$5,000 range right now so all things considered, it’s not economically worth it unless you’re selling it to offset the investment.


#14

Not necessarily. Hummie showed me his motor vs a tacon 160 today. His stator is much smaller than the tacon but the wire is much much thicker.


#15

no cooler motors from higher voltage. the classic amps and volts equal watts equation …the volts get converted to amps in the motor or something like that. Vedders site has a better explanation.

the motors are small. stators small. more power out of this little size though is definitely possible. nothing magic but theres room for more copper for sure and a bit longer stator. stronger magnets. Yea it could get longer too and that would be another way to go instead of wider.

it all depends on what you expect though. I can blast from one side of the city to the other at 25mphplus all day long. evohyax is a big guy and travels some long steep blocks but for me the same blocks arent a question and I do much steeper. I have a trigger finger and go everywhere fast and I’m happy on the terrain in san francisco. I’ve ridden the boosted and the evolve gt and these two motors blow them away.


#16

Still, I just found out that carvon is selling these Chinese EMC boards
http://www.carvonskates.com/store/p32/CARVON_Emc_--_Electric_Mini_Cruiser_with_Single_Hub_Motor.html
which are no more than these https://wholesaler.alibaba.com/product-detail/Sport-electric-skateboard-with-remote-control_60493394037.html?spm=a2700.7782932.0.0.syld9Q

It’s 6S 2500mah powered by Samsung 18650 with a 400w carvon/hub motor in 70mm wheels.
400/(6*3.7) = 18 amps per hub. It’s not very powerful but I’m still talking about a 22-24" deck.

Maybe I can reverse engineer these hubs to stuff them in 59mm wheels. I’m curious what KV these are and what stator size they use.

EDIT : Just found the complete tear apart here! https://www.flickr.com/photos/kasparsdambis/albums/72157667661928215


#17

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#18

+1 to the fact that volts DOES NOT convert to amps. Still seeing this all over the board.


#19

http://vedder.se/forums/viewtopic.php?f=6&t=6&start=60


#20

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