Wireless Charging: From Tesla to Today's EVs

Jim Motavalli

Jim Motavalli | Oct 12, 2011

As the electric car revolution unfolds, it’s generally been assumed that the future of EV charging was set. Some 80 percent of charging would be done at home, and in addition to that there would be a network of public chargers, from start-ups like Coulomb and ECOtality, but also from major players such as Legrand and General Electric (whose designer-friendly WattStation set a new standard).

But EV charging could go another way, and be largely invisible to the world at large. Cars could simply pull into parking spaces and garages and start charging, wirelessly. That’s the vision of companies like WiTricity and Evatran, and although it faces some hurdles it also shows increasing promise. In the meantime, wireless charging is already set to invade your car in another way—as an easy solution for powering up your cellphone on the go. Just dump it into a “hot” bin and soon you’ll have all your bars back.

Menno Treffers, senior director of standardization at Phillips, told me that 99 companies have signed on to the so-called international Qi protocol for wireless cell charging, so that you will be able to charge any phone from one unit. Verizon is the first out of the gate with the LG Revolution 4G phone set up for wireless charging. “Recharge your phone in under four hours without plugging it in with the Wireless Charging Pad,” the company says.

Treffers said that wireless charging—using the same essential inductive technology pioneered by father-of-AC Nikola Tesla and widely adopted by electric toothbrushes, among other applications—has long been available for cell phones, but consumers resisted the idea without a universal charging pad. “They didn’t want additional cradles on their desks,” Treffers said. “They loved the convenience of wireless power, but they were hesitant to buy.”

That is likely to change quickly—Trefers predicted that wireless charging will be the de facto method for cellphones within a year or so. The cars will undoubtedly take longer.

As the manufacturers see it, charging gear will be buried underneath parking spaces, so electrons could flow a few inches from the wireless transmitter to a receiver underneath the car. It could start automatically when the two elements came together. But there are two hurdles that have to be overcome for EVs to be charged wirelessly—the public (and government safety agencies) have to be convinced that it’s safe, and the process has to become more efficient.

Inductive charging works by generating the same kind of magnetic fields as high-voltage powerlines. The latter have been linked—though very inconclusively—to cancer risk. But in this case wireless charging supporters argue that the signal is extremely localized and presents no risk. “These fields interact very weakly with people and animals,” said Yinon Weiss, a spokesman for WiTricity, which has announced that it is collaborating with Mitsubishi and Toyota on developing wireless charging. The technology was developed at MIT, and WiTricity claims it’s a breakthrough that promises far more efficiency than traditional wireless charging—up to 97 percent, says Weiss.

Actually, 90 percent efficiency sounds pretty good until you consider that it’s somewhat like buying 10 gallons of gasoline—and dumping one of those gallons on the ground. Environmentally messy, and if WiTricity can get to 97 percent that would be an acceptable level of loss, but Treffers, for one, is skeptical that goal can be reached soon.

Nevertheless, companies like WiTricity are hopeful, and they've lined up some high-profile collaborators, including not only those automakers but major car supplier Delphi. Here's what the road ahead looks like on video:

But Rebecca Hough, a spokeswoman for wireless EV company Evatran, sees a path forward. As she explains it, Evatran’s wireless system is 97 percent efficient now—if you measure only the signal across the gap between transmitter and receiver. “But there are losses on either side of that gap,” she said, “maybe three percent on the transmitting side and three or four percent on the receiving end. So our system ends up being 90 or 91 percent efficient overall. We’re currently using off-the-shelf components to save money, but by working directly with the OEM automakers on integrating our technology into their cars and creating our own end product, we think we can get to 95 percent efficiency overall.”

Evatran, which had hoped to have a product on the market by now, has instead pushed back its product launch and is working on four separate projects with automakers. Unlike WiTricity, it declines to name the car companies. And Evatran is also launching a field trial in January, testing wireless charging with six commercial partners on the East and West coasts—again unnamed, but they include a car rental company, a municipality, a university, a large fleet and “an EV celebrity leader in the market.”

Transmitting electricity is an ultra-cool concept, but making it practical has eluded some very big players, beginning with Tesla himself. Working with the primitive technology of the period, he wanted to do something much bigger than move a charging signal a few inches—he had in mind sending electric current like email. In 1932, he told the Brooklyn Eagle, “I use the conductivity of the earth itself, and in this I need no wires to send electrical energy to any part of the globe.” Much earlier, in 1891 he demonstrated the concept to awestruck engineers by lighting up early fluorescent tubes not connected to any power source.

In 1900, the Donald Trump of his era, J.P. Morgan, learned of Tesla’s work and invested a whopping $150,000 to construct Wardenclyffe Tower, a prototype energy transmitter, in Shoreham, Long Island. Construction commenced in 1901. Alas, Marconi demonstrated a cheaper system of wireless telegraphy in 1901, and Tesla’s investors started to lose faith even as the science-fiction tower was under construction. Tesla tested his apparatus several times, with some success apparently, but by 1905 he’d exhausted all his personal savings and had to give up the project. The tower was torn down in 1917, and Tesla remained bitter about it all. “Blind, faint-hearted, doubting world!...Humanity is not yet sufficiently advanced to be willingly led by the discoverer’s keen searching sense,” he said.

Writing for the Damned Interesting blog, Alan Bellows writes, “If Tesla’s plans had come to fruition, the pilot plant would have been merely the first of many. Such ‘magnifying transmitter’ towers would have peppered the globe, saturating the planet with free electricity and wireless communication as early as the 1920s.”

Or maybe not. It’s still impossible to tell if Tesla was a visionary or just completely nuts, but he is the guy who bested Thomas Edison and delivered us the AC current we still use today. Indeed, if he were to see our current grid he’s recognize almost all of it.

It’s too early to say if wireless EV charging will become dominant. It's promising, and it's intriguing,  but it’s certainly not around the corner. “I can’t say we’ll have a production program next year,” Hough told me. WiTricity isn’t announcing anything like that, either. Interest in the technology is at an all-time peak, though, so we’ll see if these folks can succeed where Tesla so conspicuously failed.

By the way, October 16 is National Plug-In Day, with 25 events around the country, so it's a good time to be talking about this. Of course, if we go the wireless route we won't need to plug in, but that's beside the point.

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