Retrofit electric-drive powertrain for medium-duty trucks

Stating that it is challenging convention, Wrightspeed  has rolled out its Route-- an electric-drive powertrain retrofit featuring an on-board generator that is engineered for the medium-duty commercial fleet market. The company claims the Route will save over 20 times more fuel than a 100-mpg car.

Wrightspeed uses the following scenario to illustrate how the Route will save more fuel than such a highly efficient car:

Urban cars average 12 miles per hour and drive an average of 12 hours per week. That's 7,500 miles per year. If such a car got 100 mpg, it would burn 75 gallons annually. If that car were to replace a 40-mpg hybrid, which would burn under the same conditions, 188 gallons, the fuel savings would be 113 gallons per year. On the other hand, the Route can provide trucks with 44-mpg performance (cost equivalent) at an average of 30,000 miles per year at, which equals consuming 700 gallons. When the Route replaces an 8-mpg conventional powertrain that burns 3,750 gallons annually, the fuel savings is 3,050 gallons. And that amounts to 27 times more fuel saved.

By preserving existing truck chassis and bodies, Wrightspeed said its drivetrain also can avoid the capital costs, time and pitfalls of learning how to make trucks as cheaply and as well as the established vehicle manufacturers.

The company said this factor also frees it to address more than the new medium-duty truck market; because their trucks run so many miles (an average of 30,000 miles annually), commercial truck fleets are accustomed to regularly replacing powertrains.

Unlike a pure battery powertrain, the Wrightspeed Route does not restrict fleet operations with range limitations, because it has an on-board generator that charges the 40-mile battery in the field. Unlike in a conventional hybrid, the efficient electric motors are always producing the variable torque necessary to turn the wheels, according to Wrightspeed's marketing manager, Maya Giannini.

Giannini said this frees the generator from having to perform over the entire speed-load map, and allows it to operate at its most efficient point to charge the small, high-power battery. Wrightspeed calls this system architecture a Range-extended Electric Vehicle (REV) powertrain.

"It's the best of both worlds," said Giannini. "The Route combines the efficiency of an EV with the unlimited range of a mild parallel hybrid. And our generator fuel system can be fitted to run diesel, compressed natural gas, or landfill gases; so, the Routeis really the best of all three worlds."

Wrightspeed has retrofitted an Isuzu NPR with their Route powertrain. With its conventional diesel powertrain, the NPR averaged about 12 miles per gallon in testing with a metro drive cycle. With the Route, under the same test conditions, Wrightspeed measured 44 miles per gallon (on a cost equivalent basis), a more than 300% improvement, Giannini stated.

"The measured miles per gallon will vary widely with drive cycle, said Giannini. “We are modest in our calculations, because fleet operators are looking for a new technology they can trust to reduce their bottom line. They carefully track their fuel usage, and inflated efficiency numbers do nothing to further their trust in the clean tech industry."

According to the company’s founder, Wrightspeed has chosen to focus on commercial trucks instead of developing electric cars because it makes more economic sense.

"For electric drive to make economic sense, you have to displace enough fuel to pay for the technology," said founder & CEO Ian Wright. "That pretty much rules out passenger cars, because they don't burn enough fuel. Medium-duty trucks on commercial routes burn thousands of gallons of fuel annually."

Wrightspeed's Route was demonstrated to the public during a Ride & Drive event at the 2012 Alternative Clean Transportation (ACT) Expo in Long Beach on May 16.




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