Saturday, May 11, 2013

Franken Scooter

I crashed the electric scooter last winter. In the process, the fragile lithium-ion battery flew out and tumbled in the street. I put it back in. Since then it has run for only a few minutes at a time before some part of the scooter turns itself off automatically. Turning off and back on again doesn't seem to fix this. I have only been able to get it back on by pulling and re-adding the fuse that protects the battery from overloading.

I didn't want to spend the $500 for a similar li-ion so I scavenged some sealed lead-acid batteries instead. I needed to run all four of them in series to get the 48V the engine was expecting but I didn't want to charge them in series. Instead I installed a switch network that allowed me to charge them in parallel with a single 12V charger. Since the switches are in the circuit during drive and thus pulling a lot of amps, I doubled them up for each connection.

I used holes already cut in the sides of the scooter to run the wiring and a basic home-depot switch carrier. Of course, not all the switches I managed to find were the same or even fit in the switch carrier. A lot of hot glue keeps them together.

In practice, it doesn't have the acceleration of the lithium and it almost always shows 'battery low' on the console. But it was able to run up a 20deg hill for many blocks on end and still hits at least 20mph.

All in all, I consider it a win. :)

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