K2 kickboard mod with 3kw rc outrunner

Lightweight / Folding / Portable EVs - seats optional

K2 kickboard mod with 3kw rc outrunner

Postby exco » Thu Dec 19, 2013 11:20 am

I missed out on sharing most of the build process / thoughts / obstacles on my last build (GNG middrive) and thought I'd try to get it right this time ;-)

The idea is in my head for a while now. If the motor arrives this year ... which it won't ... it could be done soon. (or later)


Bought this for 37€ on ebay
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Put bigger rubber tires on it:
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and was amazed finding out you could stil buy all spare parts for cheap here.

I will probabl even get air tires if I can find 110mm ones - because that's the size of the rubber ones (initally there were 80mm PU on it) - and I already had
to slightly modify the break for the wheel to fit.
Image


I also got some busted Makita 2.5Ah, 18 V LiPo packs on ebay (paid more than I'd like to admit) ... ~50€ for 6 packs.
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Those sat around for half a year having tried to revive them - and cutting the dead cells out.
Now I made this Frankenstein pack to get them balanced.
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I will use my unliked bmsbattery smart bms with the pack later.

Because I'm too lazy atm to program an Attiny I just bought a servo tester for 50 cents and added a horribly expensive 20€
push potentiometer to it.
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Motor will be the el cheapo Aeolian-C6374-10-KV170 motor.
ESC quite possibly from Alien Power.

That's it for now.

Suggestions?
Last edited by exco on Mon Dec 30, 2013 8:25 am, edited 2 times in total. View post history.
K2 kickboard build thread (63mm, up to 3kw) | cad files on github
Backfire LRS build thread (GNG "450W" mid drive) | cad files on github
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Re: K2 kickboard mod with 3kw rc outrunner

Postby sk8norcal » Thu Dec 19, 2013 4:19 pm

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Re: K2 kickboard mod with 3kw rc outrunner

Postby exco » Sun Dec 22, 2013 3:09 pm

Thanks. Those look nice - and I already researched a bit beforehand.

After my 3rd iteration the CAD looks like this:
Image

First parts:
Image

CAD files: Github
K2 kickboard build thread (63mm, up to 3kw) | cad files on github
Backfire LRS build thread (GNG "450W" mid drive) | cad files on github
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Re: K2 kickboard mod with 3kw rc outrunner

Postby exco » Fri Dec 27, 2013 8:16 pm

More parts...
Motor mount with slots for belt tensioning:
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Back plate - old and new. The brake will be reused.
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Wheel adapters (where the bearings were before) mounted with set screws (and holes drilled into the axle).
ImageImage

Mounted together - belt pulleys also fixed with set screws (and holes drilled into the axle)
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Put together for first tests:
Image

I still need to program the controller - and buy the appropriate one from alienpowersystems.com after this one goes up in smoke (probably tomorrow)
and build some suitable battery pack.
K2 kickboard build thread (63mm, up to 3kw) | cad files on github
Backfire LRS build thread (GNG "450W" mid drive) | cad files on github
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Re: K2 kickboard mod with 3kw rc outrunner

Postby exco » Sat Dec 28, 2013 10:22 pm

"gas pedal"
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no name controller "100A" sky wing
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with 18x FDD8896 N-Channel Mosfets

First motor test


and first test run with the el cheapo controller and 6S LiPo:


Guess the motor mount isn't holding up to the torque ;-)
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electronics fixed with good old blue tape
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no load rpm 1295 ... at 4.2V*6*170rpm/V *12 / 40 = 1285 rpm ... sounds legit
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Yields in 1295U/min * 11cm * pi / 100 cm/m / 1000 m/km * 60 min/h = 26.85 km/h @ no-load ... or estimated 26.85 km/h * 0.8 = 21.5 km/h.

The controller will do 7S - so without going for a better controller I could do ~25km/h or ~35km/h @10S.
Last edited by exco on Mon Dec 30, 2013 8:26 am, edited 1 time in total. View post history.
K2 kickboard build thread (63mm, up to 3kw) | cad files on github
Backfire LRS build thread (GNG "450W" mid drive) | cad files on github
exco
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Re: K2 kickboard mod with 3kw rc outrunner

Postby torqueboards » Sat Dec 28, 2013 10:58 pm

Nice ESC. Does it also have braking like a car ESC? How are you programming it?
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Re: K2 kickboard mod with 3kw rc outrunner

Postby exco » Sun Dec 29, 2013 8:12 am

torqueboards wrote:Nice ESC. Does it also have braking like a car ESC? How are you programming it?

Yes, it has 3 braking modes. No ABS though ;-)


Programming is a real pita - with the throttle and audible feedback from the motor:
Image

Image
K2 kickboard build thread (63mm, up to 3kw) | cad files on github
Backfire LRS build thread (GNG "450W" mid drive) | cad files on github
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Re: K2 kickboard mod with 3kw rc outrunner

Postby torqueboards » Sun Dec 29, 2013 4:55 pm

Awesome, thanks for the photos. Which brake setting do you use? Are you only using motor braking or do you use the brakes on the kickboard?
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Re: K2 kickboard mod with 3kw rc outrunner

Postby sk8norcal » Mon Dec 30, 2013 1:26 am

exco wrote:Wheel adapters (where the bearings were before) mounted with set screws (and holes drilled into the axle).
Image

.


cool build,
where u get those wheels?
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Re: K2 kickboard mod with 3kw rc outrunner

Postby exco » Mon Dec 30, 2013 4:36 am

torqueboards wrote:Which brake setting do you use? Are you only using motor braking or do you use the brakes on the kickboard?

I used "soft brake" for testing to save the belt because my motor mount wasn't sturdy enough and it would already cause belt slip.

I plan on using a higher brake setting after building a sturdier motor mount.

Also I plan on re-attaching the rear brake - at the moment it doesn't have any mechanical brakes.

sk8norcal wrote:cool build,
where u get those wheels?


Thanks.
I got those on ebay.
K2 kickboard build thread (63mm, up to 3kw) | cad files on github
Backfire LRS build thread (GNG "450W" mid drive) | cad files on github
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Re: K2 kickboard mod with 3kw rc outrunner

Postby made_in_the_alps_legacy » Mon Dec 30, 2013 9:53 am

exco wrote:Programming is a real pita - with the throttle and audible feedback from the motor


3 shorts bips followed by 3 long bips then 3 shorts bips --- :lol: I know what u mean and wish u good luck for a carefull programming - your build deserves it :wink:
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Re: K2 kickboard mod with 3kw rc outrunner

Postby exco » Mon Dec 30, 2013 9:56 pm

I redesigned two parts today - the motor mount proved to be way sturdier:
Image
(upper: old - 4mm, too small cross section, lower: new - 5mm)

I weakened the other part (unfortunately no pic) too much because I tried to get a better line for the belt.

The belt was already worn down to ~25% teeth remaining - but it still had a lot less slip with the sturdier motor mount and
so the acceleration/deceleration was way better. The front wheels were even lifting off the ground a few times with
the lighter guys.


Also today we got to test the kickboard out on the "parking lot" and the cumulative distance was about 2.5 kilometers and
afterwards I could charge 2600mAh into the 6S battery pack.

~ 2.6Ah * 24V = 62.4Wh aka ~ 25 Wh/km
I have no idea if those are good/realistic figures ... I will attach a volt/amperemeter later.
This would limit the travel distance to about 5km.


The attractive figure was the top speed though ;-)
Image
Looks like 22 km/h to me ;-)

I made some videos - which unfortunately all suffer from horizontal video syndrome *darned*.
I need to check if someone else made some good ones.
K2 kickboard build thread (63mm, up to 3kw) | cad files on github
Backfire LRS build thread (GNG "450W" mid drive) | cad files on github
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Re: K2 kickboard mod with 3kw rc outrunner

Postby exco » Sat Jan 04, 2014 8:56 pm

Some more pictures:
Image
Image
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I still haven't completed the 3p6s 18650 battery pack - and I also need to measure the Wh/km and top speed with 7s ;-)
K2 kickboard build thread (63mm, up to 3kw) | cad files on github
Backfire LRS build thread (GNG "450W" mid drive) | cad files on github
exco
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Re: K2 kickboard mod with 3kw rc outrunner

Postby exco » Sun Jan 05, 2014 9:21 pm

So for now I think this build is complete.

I should still put an AT5 belt and pulleys on it after this 10mm T5 belt snaps (it's already worn down a lot).

This is the first time I actually did sth. for myself with the lasercutter at our hackerspace ...
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These are insulator rings for the 18650 cells
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The complete pack
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and even completed in shrink wrap (I bought for my ebike build over a year ago)
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Fits quite nice imho
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The top speed is now 27km/h and the measured energy consumption is 13Wh/km.

K2 kickboard build thread (63mm, up to 3kw) | cad files on github
Backfire LRS build thread (GNG "450W" mid drive) | cad files on github
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Re: K2 kickboard mod with 3kw rc outrunner

Postby exco » Mon Mar 10, 2014 8:12 am

some more pics of the kickboard evolution:
T5 10mm (left) vs AT5 16mm pulley (right)
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worn down belt vs new one
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old bent 8mm shaft vs new hardened one - is still a hack ... should get a larger diameter than 8mm
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pressing the adapters into the rims
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process of removing the old ball-bearing
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Image
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press-fitting new pulley (in addition to 2 grub screws)
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^^ somewhen I need to build a new shaft with additional bearing on the opposed side of the pulley to counter the pulley load

view of the completed rim-adapter-shaft
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Fully assembled ... again ;-)
Image
K2 kickboard build thread (63mm, up to 3kw) | cad files on github
Backfire LRS build thread (GNG "450W" mid drive) | cad files on github
exco
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Re: K2 kickboard mod with 3kw rc outrunner

Postby kkEdlund » Tue Mar 11, 2014 6:31 pm

Wow, this is probably the coolest build I've seen on this site. I actually signed up here to get help with a K2 kickboard build, but it was too challenging so I gave up and did a normal longboard. After seeing this, I think I will have to go back and finish the scooter now.

Awesome job on your build!
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