Nap Pepin had been waiting on the side of the highway near his Alberta, Canada, home for more than hour when the tow truck finally pulled up. The driver looked at the stranded electronics technologist and his homebuilt electric trike and asked, “Ran out of juice, eh?” Pepin wasn’t sure what the problem was, but he knew he still had plenty of charge. He had been tinkering with battery-powered three-wheelers since 2005, and by that point, late last year, he had spent hundreds of hours designing a battery pack to ensure that his vehicle, the Lithium Hawk, would never unexpectedly lose power.
Pepin, 48, has been making vehicles since he was a kid. After building an electric trike using some parts from a kit in 2010, he decided to make his own three-wheeler from scratch. He designed an aluminum chassis, chose an AC motor that could handle the trike’s 1,000-pound estimated weight without overheating, and selected a pair of car wheels for the front. He wanted the trike to be rear-wheel-drive, so the back wheel was critical. Conveniently, he found several people who had converted Honda Goldwing motorcycles into standard gas-powered three-wheelers and no longer needed the shaft drive that powered the bike’s rear wheel. The shaft drive was ideal for his project, in part because it allowed him to outfit the trike with highly efficient tires. He bought one, originally priced at $3,500, for $106 on eBay.
Despite all the mechanical engineering involved, the batteries presented the biggest challenge. Typically, as lithium cells run down, their performance degrades. Pepin wanted his vehicle to be more like a gas-fueled car, which provides more-consistent acceleration. So he ordered several types of lithium batteries, bought testing equipment, and spent two months analyzing the batteries’ performance under a variety of conditions.
Pepin may build a real body for the Lithium Hawk to increase its range, but right now he thinks it looks cooler without one. The vehicle gets plenty of attention and is street-legal. Pepin discovered that a manufacturing flaw in the motor controller caused his highway breakdown, and he has now corrected it. He’s also designing a system that will regulate the power sent to the battery pack to maintain a constant temperature, so that the Lithium Hawk will perform as usual even in the subfreezing Canadian winter.
Time 2 years
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.