# Pocket bike conversion



## Johnny5 (Aug 11, 2015)

Hi everyone, 

I wanted to have some fun and experiment with the new Samsung 18650 25R I got and convert a pocket bike for my nephew in the process. I would like to keep it light so I have been looking into small RC motor but Riba2233 pointed out that it might not work for my goal 60-70kmh (40mph). I was hoping to use an kelly controller or something similar for an easy throttle configuration but feel free to point out other options. I just finish testing the 4th cells and they all seem to be as good as advertised.

http://www.revolt.org.il/rv-100-with-hall-sensors/


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## riba2233 (Apr 29, 2015)

Kelly would be fine choice if you can give bit more money. Popular alternative is chinese infineon style controllers, but i don't like them personally. So revolt and kelly combination should work great!  If you have some more questions fell free to ask!


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## Johnny5 (Aug 11, 2015)

Looks like this controller is a good match and not too pricey, I should be ordering stuff as soon as I get paid. http://kellycontroller.com/kbs72101x40a24-72v-mini-brushless-dc-controller-p-506.html


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## riba2233 (Apr 29, 2015)

Yeah, it should be good! Maybe you could just take first stronger model, just in case you wanted more power one day  You can always limit controller to lower power. 

http://kellycontroller.com/kbs72121x55a24-72v-mini-brushless-dc-controller-p-529.html

Price difference is not big.


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## Johnny5 (Aug 11, 2015)

Thanks for the suggestions, although in my experience when the "swap" is done right it's usually quite easy to resell, now let's just hope it translate to electric vehicle also hehe. I almost picked up a pocket bike for 50$ this morning but the guy could be a publicist for McDonald cause it sure looked nothing like the pic.


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## riba2233 (Apr 29, 2015)

Lol good one


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## Johnny5 (Aug 11, 2015)

There's something I still don't fully get or it is really impressive but does this motor really put out 25kw you think.... http://alienpowersystem.com/shop/brushless-motors/120100-outrunner-brushless-motor-50kv-25000w-2/


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## riba2233 (Apr 29, 2015)

It can put out that much, but only at like 7000 rpm, brutal aircooling (designed for airplanes) and for very short time. 

Also, it's not easy to find controller that can power that motor easily.


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## Johnny5 (Aug 11, 2015)

Yeah I assume cooling would be an issue if I was to use it for something else but still pretty impressive for the size.


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## riba2233 (Apr 29, 2015)

http://alienpowersystem.com/shop/br...nrunner-brushless-motor-rc-boat-150kv-23000w/

This one is even more impresive, but needs 25000 rpm.


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## Johnny5 (Aug 11, 2015)

Well I do have a canoe and Id like to upgrade the minn kota on it, I didnt modify it to a square back for nothing hehe


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## Johnny5 (Aug 11, 2015)

Im starting to wonder at what level of continuous discharge on those cells you need water cooling for, I wouldnt want a bad luck like the e-cigarette blowing up in your face type one. Btw I realized you're the one selling the neat lil spot welder on endless sphere, let me know when you have some ready again Ill take one if the budget allow it, having renter can be more stressful than I thought.


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## riba2233 (Apr 29, 2015)

Sure, no problem, I'll let you know!  

I wouldn't worry about batteries, you will be drawing peaks, continuous will be less and that shouldn't be problem for cells.


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## Tomdb (Jan 28, 2013)

Now ask yourself this, how long can you pin the throttle and draw max power? 

All the fooling around a side. Weld up a pack, and build a simple discharge rig, huge resistors (long lengths of steel or heater elements) and a contactor. If you got the money or connection get a flir and an amp meter. Hook it up and turn on the contactor.

I built this setup in the past to do cycle measurements on an agm batterypack. All controlled via a microcontroller with data logging, however no need for all fancy controls unless you want them.

I would just cool the batteries in oil, the right kind ofcourse, easier to do then water cooling.


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## Johnny5 (Aug 11, 2015)

Thanks for the tip, I remember wondering why they used oil for cooling in one pack I read about, guess Ill have to do more research on it. Still trying to see option on BMS and chargers to, but its gonna have to wait till next month as I decided to rebuild another engine to finance this project... looking fwd to work a lot cleaner hehe.


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## Johnny5 (Aug 11, 2015)

Hi, now that I have 2 engine block at the machine shop so I got sometime to play around with the batteries. I tested my dewalt samsung battery and it ran at full power on my drill for 38 mins so that got me thinking about using that instead for the pocket bike. I did see a few other similar projects maybe getting 2 drill motor could get me to 30mph/50kmh speed.


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## riba2233 (Apr 29, 2015)

They probably could, but would probably have short range. And you would use them at full power constantly which would probably kill them soon.
They are cheap used, but new they are more expensive then loose cells.


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## Johnny5 (Aug 11, 2015)

So plan C already hehe, that would be the easiest of the em all, no clue if it will actually work.


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