Should I build an Electric Scooter?
I have been fascinated with the modern electric scooter as of late. I think it’s the combination of low cost power and the simple form factor of two wheels. I had ridden a number of rental scooters in southern California and enjoyed the rides. This led to doing research and learning more about them. What kind of scooters are there? How do they work? Can you build them? This led to further research and YouTube binges. It was at this point that I realized I really wanted to build my own scooter from scratch. This is related to my long-time desire to learn how to weld properly having only welded steel with a stick welder once or twice.
Research
There are ton of videos from around the world of people making custom scooters which are inspiring. They range from low tech and functional to this (which is not a scooter but uses the same core technology):
As it turns out there are many types of scooters being sold today with wildly different price points, features and power levels:
$399 Xiaomi Mi (M365)
$298 Gotrax GXL
$499 Glion Dolly
$117 Razor Power Core E90
$278 Swagtron Swagger
$169 Razor E100
$429 Razor EcoSmart Metro
$1,349 NANROBOT D4
$1,199 Mercane Widewheel
$799 Ninebot by Segway ES4
$1,100 Green Bike Electric Motion X1
Some of these cost a LOT of money! At this point I was thinking I should definitely build my own. My use case was to commute from a parking lot to an office building twice a day representing a trip distance about one-mile. There are some rental scooters in the area which I have a maybe a one in ten chance of finding on any given day. The trip cost per day of two rental scooter rides (to the office and back)averages to about $4. If I was to pay for a rental scooter every day rough math says I would hit $500 in about 125 days. I felt this was sufficient justification for investing in a scooter. I am also aware this is not a far distance: for me saving time and being able to get home quickly is the most important factor in using a scooter. I wanted a vehicle with the following requirements:
- Portable: Must be able to come apart quickly and easily. Fit comfortably in a sedan car trunk and hide well in the office (like under a desk) while charging.
- Reliable: Should function well in below freezing weather, hot weather, rain, etc. Electronics and battery should be reliable and high quality and not crap out.
- Stable: Provide a safe ride over terrain regardless of comfort. Includes things like deck surface, tire grip, etc.
- Modifiable: Able to be dissembled and put back together easily for modifications or maintenance.
- Somewhat Secure: Difficult to steal. Trackable via GPS if stolen.
Now that I had my list I needed to figure how a scooter works. Modern electric scooters and bicycles are built from the following technologies and parts:
- Lithium Ion Polymer (LiPo) battery
- Electronic speed control (ESC)
- Brushless DC motor(s)
- A throttle controller of some sort
- Disc brakes and brake handle
- Aftermarket stuff. This is everything from tubeless tires, hooks, security cables, dashboards, etc.
One of the best videos I watched while reading about components was how a brushless motor works. I thought I knew the theory but this video really helped me understand it clearly. The video is incredibly well produced and even tells you how to use an ESC with an Arduino!
Scooter Parts
Using the very popular Xiaomi Mijia M365 scooter as a reference (it’s the best-selling scooter in China) I googled eBay and other sites like AliExpress and Banggood to see how much the raw components might cost for comparison.
Battery pack
In order to build my own clone of a 36V 280WH 7.8Ah battery pack I would need to buy cells like the popular Panasonic 18650B, use a DIY spot welder to attach the batteries together, connect a BMS to each cell and wrap it all up with wires and connectors. Buying a new pack is about $70 USD.
Motor
Unless you have a machine shop you need to buy a motor and wheel combo. The 36V 250W brushless wheel motor has a peak power of 500W, max speed of 40km/h (25 mph) with a max torque of 16Nm. Buying a new one is $135 USD.
ESC
The M365 has a combined mainboard an ESC. The M365 part is $45 USD. Alternatively you can buy a 36V Throttle (with speed controller!) for $35 USD
Frame
I did not have an adult sized scooter anywhere so I would need to buy a new one or look on Craigslist. Foldable large scooters range from $50 to $160.
Other Parts & Accessories
- Wheel with brake disc $35 USD
- Misc bicycle cables
- Bicycle brake handle
- Misc switches, shrink wrap, connectors, etc.
Summary
Just buying the above parts to power drive a motor on a scooter frame without any nice to haves is already creeping above $375 without shipping. This doesn’t include the time needed to fabricate, mount, solder test and build a functional scooter with my above requirements. This was not what I expected! If I had access to more spare parts, felt comfortable and had the tools to fabricate and weld aluminum I might consider it for the fun factor. Down the road I still would like to build a scooter or perhaps an electric powered Ezroller.
Since Walmart is selling the Xiaomi M365 for $399 it seems like a good deal. I just bought one and will find out if it was worth it. Since it’s Walmart I can always return it!
