Since exco is not big on baking cookies for Christmas, he invested his time in a project he was thinking about doing for some time: Building an electrified kickboard.

The ingredients are:

• A cheap (used) kickboard form eBay
• Better wheels
• 63mm 3kw outrunner + cheap “100A” ESC
• a cheap servo tester
• a horribly expensive potentiometer
• cogged belt pulley
• drive belt
• Two used 3S 5 Ah Li-Po batteries (from his previous 60 km/h RC car build)
  
• some wire
• A day of CAD work (more, GitHub)
• A day of milling aluminum (and some minutes on a lathe) (more, more, more, more)
• A day of assembly
  It’s a pretty bare-metal job. Instead of adding a microcontroller and programming some firmware he opted for a simple push potentiometer to control the motor speed (video of first motor test)

A first try to build a belt tensioning mechanism by sliding the motor mount looked nice enough but didn’t manage to hold up to the torque and had to be re-designed.

Once that was sorted out it was time for a test ride. Impromptu as always the two battery packs went into his trouser pockets (don’t try this at home) and were connected via a long Y-cable to the motor controller. He’s currently in the process of building a new battery pack from used Makita battery packs with 18650 cells.

Check out the video of the first test drive:

If you’re planning to built your own e-something, Maedler has a nice online calculator for dimensioning the drive train.

For this build the no-load RPM was measured at 1285 rpm which would yield a theoretical maximum speed of 26.85 km/h. Actual measured speed was 22 km/h using 6S Li-Po cells or around 25 km/h using 7S cells.
Mind you, on a kickboard this is scary fast and quite literally brings tears to your eyes from the cold winter wind draft.

There’s also a more detailed build log over at the Endless Sphere forum and a whole bunch of extra photos.