Small Company Sees Future in Range Extender Trailers for Electric Vehicles

Small Company Sees Future in Range Extender Trailers for Electric Vehicles

By John O'Dell November 1, 2010

By John O'Dell, Senior Editor

The idea's not new, but commercial execution would be: a follow-along generator that produces juice for battery-electric vehicles to keep 'em running long after their initial grid-derived charge is depleted - an EV range-extender.

Electric Motors and Vehicles Co., an Indiana startup with a background building specialty camping and hunting trailers sold through Jeep dealers, says it is developing a power regeneration unit - PRU - that will turn any EV into a long distance runner.

EV pioneer Alan Cocconi and Tom Gage developed a similar concept more than a decade ago for a prototype electric sports car their company, Southern California-based AC Propulsion, built to showcase the power of electric drive systems.

Their T-Zero, which posted a 0-60 time of 3.6 seconds, could become a cross-country traveler when Gage and Cocconi hitched up a small trailer called the Long Ranger that was fitted with a 20 kilowatt gasoline generator and the necessary connector cords.  It was attached to the rear of the T-Zero via a so-called smart hitch, which lets the trailer act like it is part of the car, making it easier to back up and to maneuver in reverse and in tight quarters.

The PRU takes things a few steps further said EMAV co-founder and president Wilhelm Cashen.

"It is self-propelled," he told us in a recent interview. Because of its on-board propulsion, the car doesn't tow the trailer so much as the trailer follows the car, linked to it by the hitch. Thus, said Cashen, "it produces hardly any drag so it doesn't make the car [batteries] work harder to pull it. And it produces enough power to also keep charging the EV's batteries."

Cashen said the company hopes to have a proof-of-concept ready to show by early January and to have PRUs on sale by the end of 2011 or early 2012.

EMAV, which opened its doors about a year ago and has a dozen employees including Wilhelm and co-founder Keith Rosenbaum, got started building trailers for Mopar, Chrysler's parts divsion. The company's located in Wakarusa, near Elkhart - the trailer capital of the country and home to the new Think USA EV plant and the Navistar electric truck conversion facility.

The small trailer chassis EMAV developed will be the foundation for the PRU, said Cashen, who described the initial model as a 6-foot trailer with extra storage for occupants of the EV and a 65 kilowatt generator powered by a small diesel motor.

Proprietary control electronics will transfer the load on the trailer hitch - which varies with speed and the drag that increases as a trailer is pulled up grades - into a signal that tells the gen-set how much juice to produce to both propel the trailer and an send extra power to the EV, Cashen said.

The rig - which exerts little drag on the EV except when going uphill - burns about 2 liters of fuel per hour, he said - the equivalent of 1.05 gallons every two hours (the specs he later provided - left, click on spec-sheet to enlarge - showed consumption of 0.8 gallons per hour at peak output, 1.5 gallons per hour running at 50 percent of peak).

The size of the generator and the on-board fuel tank will be variable, depending on the distance between fillups that would be designed into each PRU model, he said.

Cashen, a power control engineer (he described partner Rosenbaum as the business guy, an attorney and the company's CEO) said the idea behind the PRU is to give EV drivers an option that drivers of extended-range plug-in like the Chevrolet Volt have - to be able to drive all day without worrying about where to find a charging plug.

The difference is that with a Volt or other range-extended plug-ins under development, the all-electric range before the on-board gas generator kicks in is fairly limited, around 40 miles.

Cashen believes the PRU will give EV drivers the best of both world - the ability to dive their battery-electric cars to the full range of the grid-charged battery pack, perhaps 100 miles on average, without any tail[pipe emissions, with the option to hook up the generator-trailer for longer trips.

Drawbacks?

Well, the price tag is steep - Wilhelm says EMAV is targeting $15,000 retail.  That's on top of whatever the EV costs.

And the trailer will need a place to stay when it s not attached to the EV, something that would tax many people's garage or yard space.

Cashen says EMAV's market plan sees the PRU as a limited-appeal addition to the EV driver's arsenal and that the company's goal is just 10 percent market penetration.

EMAV is a development company and would not be building the generator-trailers itself but rather would work though contract manufacturers and market the finished trailers to car makers and dealers to sell to the EV buyers.

"For electric cars to be truly viable for a mass consumer audience, we need to bridge the gap between low-range electric vehicles that can travel moderate distances to electric vehicles which can truly become the sole family vehicle," said Cashen.

"Our goal is to move the marketplace beyond the first generation of electric vehicles to more powerful and rugged cars that also have endurance. This will evolve the electric car paradigm from a supplemental to a primary car for consumers."

Or at least for those who have an extra $15K - admittedly cheaper than buying a second, gasoline-powered car for long trips, although it would cover a lot of rentals - and a place to keep the trailer when it isn't needed as a range-extender.

We expect, though, that  the PRU or products like it, will find favor with some portion of  EV buyers and could even put EVs on some consideration lists they'd never otherwise occupy.

And that's not a bad thing at all.

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PRU rendering and spec sheet courtesy of Electric Motors and Vehicles Co.

T-Zero photo courtesy AC Propulsion via GNU Free Documentation License.

John O'Dell:  is an AutoObserver Senior Editor. Follow @AutoObserver on Twitter.