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Reducing E-Waste with Analog Solar Bikes

Apr 18, 2024

in: community

Electric bicycles, or e-bikes, have become one of the fastest growing markets in human transportation. Combining many of the advantages of both a bicycle and a motorcycle, while being power efficient enough to charge with solar panels, no wonder over a million e-bikes were sold in the US in 2023. However, unlike purely mechanical bicycles, e-bikes produce e-waste. We propose a solution.

Electric bicycles are, like most consumer goods, designed and manufactured to provide the most utility for the lowest cost. Multi-layer PCBs, motor controller ICs, surface mount device (SMD) components, conformal coatings, and of course solder are all used in the production of nearly all consumer electronics, e-bikes included. However, when an e-bike breaks down, repairs often mandate the replacement of the full controller assembly or battery module. This, of course, produces multi-material e-waste, which is difficult to recycle and toxic to dispose of in landfills. While this is no worse than other consumer electronics, for many e-bike users it may be unnecessary.

Robots Everywhere founder MK Borri designed a “controllerless” e-bike, built entirely from analog components. Five MOSFETs, a filter capacitor, a 3904 transistor, a few resistors, and trim potentiometers for tuning are all that is needed to run the motor and provide speed control for this bike. It’s truly a work of art. It uses the existing chainrings, and allows the rider to provide manual power from the pedals. The most important thing, however, is that it is designed to be repaired using no tools other than a soldering iron and wire strippers, and produces the absolute minimum e-waste: only the exact failed components have to be disposed of. All together, this allows for a much lower build cost, and near zero repair cost.

“Why is this not everywhere?” is a valid question to ask, and the answer is tuning. Because this is an analog circuit, many variables exist, requiring adjustable bias resistors. Every individual assembly must be tuned after installing on the bicycle, creating additional labor during installation. Many manufacturers find this inefficient, and many users find it inconvenient, though most bicycle owners are used to a bit of geartrain tuning on a regular basis.

As such, our goal is to release this design, with a schematic, PCB layout, and bill of materials, under an open source hardware license. We hope that makers and environmentally conscious individuals will adopt this design of an efficient, low-waste ebike, and keep a bit more junk out of our landfills.

For more information on the design itself, including the prototype schematic, refer to the previous article.