One reason electric and plug-in hybrid vehicles have hit the market with a thud is that there are strings attached - drivers of models such as the Chevrolet Volt and Nissan Leaf must plug in to recharge the battery.
A number of companies are developing ways to cut the cord, to replenish the battery wirelessly with a mat that sits on the floor. Coils on the underside of the car engage the charger when the car is parked over them. The mats are plugged in while the car isn't. Automakers and suppliers expect to have the chargers ready for sale around 2015.
"The feedback we see from initial Volt and Leaf buyers is that, 'Gee, these cords get really dirty; gee, these cords get all tangled; what a pain in the neck'," said Phil Gott, an IHS Automotive analyst specialising in power-train research.
"A wireless charger truly gives you total freedom."
Automakers are looking to such vehicles to comply with regulatory pressure to boost mileage and pare emissions. But electric and plug-in vehicles aren't even considered by 96 per cent of consumers globally, Deloitte LLP said in a 2011 survey.
Price and driving range deter purchases, as does charging time, which ranges from three to more than eight hours, Deloitte said. Tesla Motors, the electric-car maker that delivered its first wholly company-produced sedans recently, had said it's close to announcing a plugged-in "supercharger" network that can re-power one of its cars in less than an hour.
Nissan, Delphi Automotive, Volkswagen's Audi, Toyota, Mitsubishi, Qualcomm, Evatran and Brose Fahrzeugteile GmbH & Co are among companies developing wireless chargers.
General Motors, the largest US carmaker and maker of the Chevrolet Volt, invested $US5 million (NZ$6.1m) in a private company called Powermat and was joined by Procter & Gamble and Jay-Z last year. So far, GM says, it's using the technology only to charge smartphones and other devices in the car.
The chargers work one of two ways: By induction, similar to the way the battery on an electric toothbrush charges when it's set back on its base, or by magnetic resonance.
Delphi's charger, using a technology developed by WiTricity, uses a magnetic field to transfer the charge between coils in the mat, about the size of a laptop, and bolted on to the underside of the car. The gap can be as wide as 25 centimetres, depending on the car's clearance, said Randy Sumner, Delphi's director of hybrid electric vehicle business and technology development.
The charger, using technology developed at the Massachusetts Institute of Technology, can send 3 kilowatts of electricity quickly enough to recharge a battery in about four hours, Sumner said. Two coils are tuned to resonate at the same frequency, creating the connection. Audi, Toyota and Mitsubishi also are working with WiTricity.
Magnetic resonance allows more margin for error than inductive charging, Sumner said. Inductive chargers require more precise alignment for recharging. Magnetic resonance allows for a lateral, or left-to-right, range of plus or minus 10 centimetres, he said.
The chargers probably will sell for more than $US2000 (NZ$2463), at least twice the price of current charging stations, Sumner said. They are also less efficient. About 10 per cent of power is lost in transmission, and the goal is to cut that by half, Sumner said.
Kinks are still being worked out. A charging mat is flat and warm, so how to keep a family cat from napping on one? How does a user keep metal away?
A group of engineers from suppliers and automakers has been meeting for a year to solve such problems and develop standards to make all chargers work on all cars, Sumner said.
The other hurdle is the market. GM sold 7671 plug-in hybrid Volts and Nissan 9674 all-electric power Leafs last year, according to researcher Autodata Corp. So far this year Volt and Leaf combined deliveries show a 55 per cent slide from last year.
The Volt has a starting price of $US39,145 ($85,000 in New Zealand) while Leaf's is $US35,200 before tax credits. Electric versions of normally petrol-powered models also cost more. Toyota said its electric RAV4 sport-utility vehicle, to be sold in California, will cost $US49,800, more than twice the price of the petrol version. Tesla supplies the electric RAV4's batteries and motor.
Pike Research, based in Boulder, Colorado, forecasts sales of 359,000 plug-in and all-electric vehicles in the United States by 2017. AutoPacific, an industry researcher in Tustin, California, estimates that plug-in and electric car sales will total 320,000 units in 2017.
Offerings of rechargeable vehicles are expanding. Toyota last year introduced a plug-in version of its Prius hybrid car. Ford began selling an electric Focus this year and a plug-in version of the Fusion goes on sale next year.
Delphi chief executive officer Rodney O'Neal said consumer demand hadn't caught up with technology.
"There are a lot of things that are possible," he said. "The question is, can you do it cost effectively and does the world care, and can you make money and create value for your shareholders?"
Wireless public chargers may mitigate concern that drivers will run out of electricity before they can get home to recharge.
The number of public charging stations globally is projected to more than triple this year to 98,503 from 28,479 in 2011, according to a Bloomberg New Energy Finance report. Most of the new stations will be in China and Europe.
A test under way in London is looking at how to embed wireless charging mats in city streets and parking garages, said Andrew Gilbert, Qualcomm executive vice president. The company wants to license the technology to automakers and charger manufacturers.
"Plug-in is not a bad solution; we just see this as a great opportunity to really improve the experience," Gilbert said.
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