Electric Scooter

Intro:

I’ve wanted to give a scooter an electrical system for a while now ^-^. Moreover, I’d like to ride a scooter that has suspension and pneumatic wheels (for all the bumpy roads on campus), a carbon-fibre deck, and be foldable – all ideas that popped up in my head after commuting around the MIT campus over the summer. But actually making a scooter frame will be interesting, and I hope to garner some skills from it: welding, working with composites, and design of the battery power system. In late October, I got techX funding to work on the scooter, and I finished it in the end of January.

Power System:

Charles G. taught me how to put together battery packs and also supplied me with Li ion batteries (though from a few years back…2006?). Nevertheless, batteries. 3.3 V each, with ~2.2 Amp-h. Some steps to put together a battery pack (for notebook purposes).

  1. Bin batteries according to open circuit voltage – for batteries sitting out for so long, some have left their voltage. (choose only 3.3 V, I guess). Positive end = pin end.
  2. Buy balance connector (according to the amount of batteries in one series pack. For example, with a 5 cell pack, you need 6 pins – 1 for +, 1 for -, and one for each junction). Also buy 1/4″ wide grounding braid to connect.
  3. Assemble. Here’s some guy’s tutorial
    • Hot-glue batteries together
    • Scrub the tops/bottoms of bottom to ensure solder attaches
    • Put solder on ends you want to be attached, spreading with a chiseled-tipped soldering iron. Remember to angle iron and use lots of solder (and spread slowly) but also to complete the task quickly in order to not heat up the battery excessively.
    • Use big iron for + ends and smaller iron for – ends
    • Don’t short cells together with your soldering iron.

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Entire electrical system: batteries shrink-wrapped connected to kill power switch, motor controller, and motor2015-01-24-14-24-02-e1474430262343

Materials

I gathered supplies from around MIT, which simply has a wealth of materials (mostly, Charles has a ton of EV parts and batteries that drastically reduced the scooter’s cost).

  1. Drive Train
    • Disk Brake: works more effectively than a band brake – bought from a scooter system; waterjet an adapter
    • Back suspension : Added a suspension spring from a bike to cushion
    • Bike Hand Lever for braking

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2015-01-15-17-21-142. Frame

  • thicker, pneumatic wheels – to lessen effects of bumpy terrain
  • used remnants of my old scooter
  • Bamboo Front Fork: to lessen weight (and learn how to use bamboo), I made my front fork out of bamboo, heat treated with a blow torch, and then fastened to other pieces with hemp string and epoxy. This process is similar to how bamboo bikes are made.

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