Karmin, a Mountain View resident, rides around town on a contraption of his own making: a solar powered three-wheeler. He often can be seen at the helm of this strange vehicle cruising down Castro Street on the way to Posh Bagel, his favorite downtown eatery.
The electric trike, which he made seven years ago out of junk motorcycle parts and about $200 worth of steel, would go nowhere without its special canopy: four solar panels mounted over the driver's seat.
By day Karmin is a tugboat captain who works out of San Francisco. His commuter car is a Honda Insight hybrid, which he drives from Mountain View to a San Francisco dock. Although the Honda gets up to 70 miles to the gallon, Karmin has plans for an affordable electric vehicle that can make the 100-mile commute without gas.
In the meantime, he built his trike for running around town, and for towing behind his van when he travels across the country. It won't win any awards for looks or speed, but Karmin believes that over the last seven years his vehicle has demonstrated the utility of a $2,400 set of solar panels, which constantly charge the trike's batteries.
Using only eight six-volt batteries, the trike's top speed is about 35 miles per hour, with a range of about 30 miles. His normal routes around town allow the panels to keep the batteries charged — although, if heavily used, the batteries may need two days for to re-charge using the panels (a regular wall socket charger could do it in a few hours). Karmin has a voltmeter mounted on the trike to keep track.
Altogether, the batteries — placed between the rear wheels to keep the vehicle from tipping — put out a paltry 48 volts. But add more batteries and a higher amperage controller for the twin Etek motors, and the trike would really "jump," Karmin said.
One of the trickier parts to make was the brakes, he said. The motorcycle discs that came with the wheels wouldn't stop the trike fast enough, so Karmin had some large discs custom-made. The trike doesn't have reverse — Karmin said he's foregone the $300 reversing solenoids, for now.
"I just push it back with my feet," he said.
When the Voice caught up with Karmin, he was loaning his trike to about a dozen construction workers who were using it as a self-contained power supply as they tore down a house in Palo Alto. Karmin said it provided more than enough power for the job — "way too much," in fact. The crew's gas-powered generator was not working, and besides, it would run continuously, even when not in use, burning up to four gallons of gas a day and spewing out however much pollution.
Karmin is no newcomer to solar power; he even sold solar panels in the late 1970s. Back then, he said, the belief was that the panels would pay for themselves in one year over power produced by a gas-powered generator. "Now it's a lot faster," he said.
For his next EV project, Karmin said he would invest in a set of expensive lithium nano-phosphate batteries made by A123.
"A good battery that works, that's all we need. Then fuel cells can go to hell and gas can go to hell," he said. "Once an electric vehicle can do 500 miles on a charge, there's no reason to do anything else."