Electric Car Charging Goes Wireless

By · December 14, 2011

Evatran Charger

Evatran has reduced the size of its inductive charger and increased efficiency. (Evatran photo)

Inductive EV charging—look, ma, no wires!—is gaining momentum, with Daimler testing concepts for the new battery version of the B-Class Mercedes and Nissan actively contemplating making it an option on the 2014 LEAF. Wireless charging leader Evatran will sell wireless kits for the LEAF and Chevy Volt next year, and it’s even hooking up with Sears Home Services to bring its Plugless Power to the masses.

The basic technology is familiar from wireless phone charging and the electric toothbrush. There are a few basic obstacles to creating larger versions for cars: high cost; the 10 percent average energy loss today when transferring power from a floor-mounted transmitter to a car-based receiver; and a start-from-scratch regulatory climate. But there’s no question that wireless charging, which creates a magnetic field to pass an electric charge from one coil to another, is on the ascendancy. It certainly addresses anxiety over having to learn a new way to fill your car up with energy—all you have to do is park, and these automated systems will do the rest for you.

Technology on the Move

It’s far too early to tell if wireless technology will eventually triumph over the wall-mounted home charging system, and no automakers have formally adopted it. “All we have done is shown this technology,” says Nissan’s Steve Oldham. “We haven’t confirmed anything. The stuff that is out there is speculation.” But Popular Mechanics claims that wireless will be an add-on for the luxury Infiniti version of the LEAF in 2014. The Rolls-Royce 102 EX Phantom, which I recently test drove in New York, is also set up to use a wireless charger from HaloIPT.

In the system that Nissan demonstrated, drivers simply align their vehicle over an inductive charging mat. A dashboard-based navigation system uses sensors to guide the rear wheels into place. The touchscreen hosts buttons to start and stop a charging session.

In Alignment

Daimler has teamed up with Conductix-Wampfler on plug-free charging for the Mercedes E-Cell. According to Conductix, one big hurdle is the need for exact alignment between the charger and the vehicle. The signal can travel only six inches or so, so the driver is likely to need an automatic parking system to ensure a good lock-in.

Nissan demonstration of wireless electric car charging.

Major auto supplier Delphi and wireless leader WiTricity have their own system under development, using technology invented at MIT. Randy Sumner, a spokesman for Delphi Packard Electrical/Electronic Architecture, told me that automakers have shown considerable interest in wireless charging, which could accompany the second-generation EVs coming out in the 2014-2015 time frame.

Priced Like Navigation?

Wireless chargers have definitely gotten smaller and more efficient. Dave Schatz of WiTricity told me he expects consumer systems to eventually cost no more than car-based GPS navigation. Evatran’s Plugless Power floor-based unit is now the size of a small hubcap, with up to 97 percent efficiency between the charger and the car. It’s also more forgiving of poor alignment. Evatran is testing the system on a fleet of a dozen Chevy Volts. But it’s still far too expensive, at $5,000 for an all-in system in 2012.

The General Electric wall-mount WattStation is now available at Amazon.com for $1,099 (none used yet), so Evatran’s Sears play makes sense. According to co-founder Rebecca Hough, Evatran will make its wireless hardware kit (for the Volt and LEAF) available in 2012 for approximately $2,500, with installation (unpriced so far) extra. The basic installation is for people who are lucky enough to have dedicated 240-volt lines in their garages; the standard install includes that line.

Some regulatory and safety issues have yet to be worked out. Underwriters Laboratory (UL) and the Society of Automotive Engineers (SAE) are set to introduce standards for wireless in the second quarter of next year (fast for SAE), and waiting for that has hindered plans for commercial and public wireless charging. Obviously, you’d want this at Starbucks and the big-box stores, but companies aren’t likely to go ahead without the standards in place.

Evatran Charger

No longer science fiction, wireless home EV charging could make juicing up even easier. (Evatran photo)

The International Commission on Non-Ionizing Radiation Protection (ICNIRP) issues standards for the strengths of magnetic fields, and Hough says that Evatran has no trouble meeting them. She also says that wireless will incorporate many of the safety provisions built into SAE’s J1772 standard, including safety interconnects and shutoffs.

By the way, claims for inductive charging are somewhat confusing, because there's a difference between the efficiency measured charger-to-car and the overall system. Evatran boasts an only three percent communications loss, but the overall system is currently at 91 percent. Company engineers think that 93 or 94 percent system efficiency is doable relatively soon, but going beyond 95 percent is a long-term prospect. Would we be happy with a gas station that spilled five percent of the gas on the ground?

John Gartner, a senior analyst at Pike Research, says that widespread will take years to roll out. “It’s of interest to most top automakers, many of which have internal programs in development. The consumer market is still years away. There’s still no common SAE standard, and you don’t want vehicles tied to charging docks, and the cost ($500 per car) is too steep to include on vehicles that aren’t going to use it all of the time. The technologies are all pretty different, so unlike cabled charging, some companies would be left out of any standard that is eventually passed. Qualcomm surprisingly is going after the market in a big way with its recent acquisition of HaloIPT.”

Still, wireless is probably here to stay, but it will take time to develop. “Pike Research sees the market growing slowly from 2013 ($26 million globally) to $233 million globally by 2017,” Gartner said. “Fleets that can share charging docks are the mostly likely early adopters.”

The bottom line here is that inductive charging, which appeared to be abandoned from the last generation of EVs, is now looking more and more practical as a long-term solution. Even if wireless does eventually triumph, however, wired charging is still likely to dominate the early EV years simply because the units will be in place and working. But there’s no reason they can’t happily co-exist.

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