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Electric scooter

Twice a year in my suburb (like most other places I guess) there's a council clean-up week, aka Free Shit Week, when the neighbourhood becomes a supermarket full of free stuff, most of which is crap. But one man's trash is another man's possibly slightly useful trash, so I like to wander around and see what's on offer. One of the things I've found is an old electric scooter. It didn't work, but why let that stop me?

Batteries

The batteries that were in the scooter were flat, and they wouldn't charge. So, after verifying with a benchtop power supply that the motor actually worked, the first step was to replace the batteries. I got two 12V, 15Ah sealed lead-acid batteries the same size as the old ones, and a charger. That was easy, but the batteries are pretty expensive. Luckily I have a secret contact deep within the battery industry, with access to batteries at wholesale prices.

Scooter batteries

With the new batteries the scooter's 180W motor ran, but it just ran continuously at full speed. The throttle did nothing. In my eagerness I hopped on anyway and zoomed up the footpath, assuming I would be able to reach down to the power switch at the base of the scooter, while moving, and switch the scooter off.

I was wrong. I ended up having to jump off the scooter and heave it by the handlebars into the air while the back wheel spun madly. Unfortunately I'd forgotten how heavy the thing was with eight kilograms of batteries in it, and in the chaos and confusion I failed to keep the back wheel back off the ground, causing it to zoom into a hedge. Still holding the handlebars, I rather ungracefully managed to reach the switch and turn it off.

All in all, a successful trial run.

Brake

The brake lever assembly was broken off when I found the scooter, so I figured I'd better fix that up before I bothered fixing the throttle. I went and bought a hose clamp, placed it over the affected area and tightened it up. A pretty crude solution, but it works.

Scooter brake

Throttle

A bit of testing and Googling revealed that the issue with the throttle was due to the Hall effect sensor in the handle not working properly. This was lucky because if the sensor had been working properly, the problem would have been with the controller. The controller interfaces the throttle signal and power supply with the power output to the motor. I couldn't repair or reverse-engineer the controller because inside its black plastic casing, all its circuitry is entombed in some kind of concrete like substance, making it a black box in both the literal and figurative senses.

The other fortunate thing is that for an electric scooter the Hall effect sensor can be replaced by a 5k potentiometer and it still sort of works. I went out and bought a potentiometer, some wire, and a connector to plug it into the controller. I soldered it up and ran the wire up to the handlebars where I taped the potentiometer next to the grip.

Scooter throttle

I didn't think to buy a knob for the potentiometer so I stuffed an old wire spool onto it.

Scooter throttle with wire spool as knob

That completed phase one of the scooter project, getting it into a useable state. It's pretty fun to ride, if a little dangerous. The tires are solid and of course there's no suspension, so it's pretty shaky on the crappy footpaths around my house, and it tends to need a bit of a push getting up hills. But all in all it's a pretty cool thing to have around.

Complete scooter

Complete scooter

Complete scooter