While it’s easy to dismiss wireless charging for smartphones or tablets as mere gimmickry in its present state, the technology shows serious promise out in your driveway—where it could play an important role not just in how you charge your vehicle but in how quickly electric cars catch on.
Wireless charging (also called inductive charging) systems use electricity from the grid to generate an electromagnetic field that can recharge batteries across a gap, such as between a charging pad on your garage floor and a car parked above it. Although the technology has been teased for decades, the latest iterations of wireless charging get over two engineering hurdles: the lack of physical flexibility between the charging pad and the vehicle’s receiver, and the energy lost by such systems.
Wireless charging used to be less efficient than a physical charging port, but the latest systems from WiTricity, Qualcomm (Halo), and Samsung are doing better. WiTricity’s new original-equipment system achieves excellent overall efficiency numbers of 91 to 93 percent, measured from the power grid to the car battery, while a typical plug-in Level 2 charger is considered efficient at 88 percent or so, and Level 1 (110-volt AC socket) systems are considerably less efficient.
That WiTricity system, General Motors advanced technology spokesman Kevin Kelly confirmed, is in a “prototype testing” phase with the Chevrolet Bolt EV and Volt—although any future availability for these models isn’t yet a given.
Alex Gruzen, WiTricity CEO
According to Alex Gruzen, CEO of WiTricity, the efficiency gains are achieved through the MIT-born company’s technical focus on physics and resonant frequencies. “If you can create a very efficient resonator, some magic occurs, and you can move energy with great efficiency,” he explained. Gruzen said that with the company’s current technology, it can fine-tune the system to work with four to 10 inches of ground clearance. And that—with a guidance system to help the vehicle get centered—allows a lot of flexibility for the type of vehicle and the way the charging mat is mounted in a driveway, garage, or parking lot.
A Single Standard That Should Just Work
WiTricity is endorsing a single industry standard for wireless charging—and compromising on a frequency that would work around the world while maintaining power levels and efficiency. The SAE standard in the works, which the engineering group calls J2954, establishes an 85-kHz frequency band and covers four power levels: 3.7 kW, 7.7 kW, 11.0 kW, and 22.0 kW. The standard will also support interoperability among pads and receivers from different companies.
At present, the 22-kWh power level will be out of reach for most household installations—although it could be a lower-cost alternative to fast charging for commercial installations at restaurants or shopping centers. Higher levels of up to 50 kW are in the works, but those are reserved for commercial vehicles, such as electric buses.
Earlier this month, the Idaho National Laboratory (INL), in collaboration with six companies (including Toyota, Nissan, and Jaguar Land Rover) completed bench testing in support of J2954 and engaged in a series of interoperability tests. Much work toward the standard has already happened.
By the time the standard is finalized in early 2018, several models might already be on the market with inductive charging. The 2018 Mercedes-Benz S550e plug-in hybrid is expected to offer or include the feature—in that case, supplied by Qualcomm—and Nissan has hinted that it could be available on the next-generation Leaf, coming as a 2018 model. Several other automakers are involved with WiTricity: Toyota is an investor, and the company earlier this year announced a collaboration with Nissan.
Expense has been another deal breaker for inductive charging systems. The cost for the charging pad, receiver, power management hardware, and control software can add up to several thousand dollars. But WiTricity CEO Gruzen expects that prices won’t remain the sticking point for long.
“Like everything in this business, the costs are falling dramatically as volume increases,” he said, mentioning the company’s work to involve the China Automotive Technology and Research Center (CATARC), which guides such standards in China. “Common architecture means scalability, which means that the components go to volume faster.”
WiTricity is not the only company that believes the technology is reaching a tipping point. Evatran, which manufactures the Plugless Power line of aftermarket wireless chargers—for models including the BMW i3, the Chevrolet Volt, the Nissan Leaf, and the Tesla Model S—also plans to enter the original-equipment market soon, and it already has in China. “We expect that 2017 will be a defining year for OEM announcements on wireless EV charging based on the intensity of interest we are seeing across the board,” said Steve Cummings, Evatran’s senior manager of brand and marketing strategy.
Are Autonomous Vehicles the Missing Link for Sharing?
“We see wireless charging as being essential to the future of mobility,” said Gruzen. For car-sharing fleets and autonomous vehicles—and anywhere it’s not the operator or passenger’s responsibility to use a physical charger—wireless charging at designated parking spots could help keep vehicles in use a greater portion of the time.
The new standards apply only to stationary systems. The possibility of dynamic inductive charging is a related technology, but it involves systems embedded into roadways to charge vehicles continuously along some routes—potentially reducing the need for vehicles to carry around big, bulky battery packs. As you might guess, that involves a series of more complex infrastructure questions.
In the meantime, the simpler idea of shedding the charge-cord hassle at home and making nightly charging second nature could be what warms up more people to electric vehicles.
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