Home-built solar electric scooter fits in a suitcase
By Ben Coxworth
March 25, 2011
Three years ago, Terry Hope was working as an engineer on a Canadian schooner. He wanted to take along an electric scooter, but was told by the captain that he couldn't bring aboard anything that couldn't fit in a suitcase. His response, naturally, was to set about designing an electric scooter that could fit inside a suitcase. Flash forward to 2011, and his home-built solar-electric Kinetic Photovoltaic Vehicle (KPV) is on the road.
Terry started with a stock steel scooter frame, and augmented it with a variety of hand-made and off-the-shelf parts.
In its current incarnation, the KPV has a 396 W-h/24-volt battery, 28 W-h/12-volt booster battery, 10.8-volt ultracapacitor bank and a 12-volt kinetic generator.
The batteries can be fully charged from mains power within 15 to 45 minutes, and the scooter can travel around 13 miles (21 km) per charge.
Power can also be supplemented by the scooter's 50-watt solar array. This takes the form of 14 monocrystalline cells contained within five panels mounted on the front of the bike, which are intended to serve as an aerodynamic fairing. Using rocker switches, the rider can direct power from the array into either of the batteries, or the capacitors.
The KPV weighs 44 pounds (20 kg), which makes it a bit heftier than another portable last mile transport solution we covered recently - the YikeBike. The solar array adds another 6 pounds (2.7 kg) when attached. Its top speed is 20 mph (32 km/h).
The kinetic generator consists of a sprocket mounted on the non-motor side of the rear wheel, which is linked to five gears that rotate a set of small 3-phase alternators. These alternators convert alternating current to direct current with a claimed 74 percent efficiency, and store the electricity in the capacitors. A booster switch gives the rider access to these power reserves.
Terry hopes to have Version 2 of the KPV completed within the coming months, which he says will be lighter and faster, with increased torque and solar capacity. He's also considering adding lights, laser guidance(!), and a 7-inch WiFi/3G/4G/GPS bluetooth touchscreen display – he might be needing a bigger suitcase.
"I don't think about mass producing it, at least not at this time and date," Terry told us. "However I do think that with lighter stronger materials and improved solar efficiency possibly with CIGS [copper indium gallium selenide], soon someday an ultra portable solar vehicle will be widely accepted. This would be one of the main reasons for continuing the project."