The idea of putting some extra energy into a trailer that attaches to your all-electric vehicle when you need it is not a new one. Electric vehicle (EV) drivers have been designing their own for years, for example the EV Pusher, made by R. Sparks Scott, which took the front half of a 1978 Volkswagen Rabbit running on biodiesel and then pushed a 1981 VW Rabbit modified to be a pure electric vehicle. If you don't think the DIY method is for you, take a look at the PRU from new company Electric Motors and Vehicles Company (EMAV). PRU stands for Power Regeneration Unit, and it's a, "self-propelled electric vehicle power regeneration system that substantially extends the range of any electric vehicle." How this will work is not exactly spelled out in EMAV's press materials (or very odd website) but Wired provides the details.
The trailer connects to your EV through something called the Smart Hitch, a connector that can send, "a signal to the speed controller based on the pulling, tugging or tension that's delivered to the hitch when the host vehicle moves," EMAV founder and president Wil Cashen told Wired. The trailer has a 240V DC motor to propel itself, "so that the electric car never has to tow anything." The trailer holds some lithium-ion batteries and a four-cylinder, 750-cc diesel generator that, Cashen said, can provide 700 miles of range using six gallons of gas. The six-foot trailer can also hold some gear and is expected to cost $15,000. Ouch. A prototype PRU should be coming in early 2011 and production versions could be available in the second half of the year. The PRU is an expansion of the partnership EMAV has with Mopar to make and sell the Mopar - Jeep Off Road Camper/Trailer.
The PRU is not like having a Chevrolet Volt where you can take the range extender out when you don't need it. From what we can understand, the trailer doesn't charge an EV while driving – since today's EVs can't charge while driving anyway. The Nissan Leaf, for example, will not move if the charging cord is plugged in. Instead, the trailer is simply a way to recharge your EV when you're nowhere near an outlet. We think that Smart Hitch better lock the trailer to your car, because if you're toting around $15,000 on wheels, you don't want it cruising away while you're taking a break somewhere. Thanks to everyone who sent this in!