Wireless charging unleashed

Imagine charging an electric vehicle wirelessly in much the same way you can charge an electric toothbrush, shaver or some mobile phones. No more hassling with awkward plugs, seen by many as a major factor slowing the growth of EV sales.

Wireless charging for EVs is on the verge of initial deployment, starting with the Mercedes-Benz S500e plug-in hybrid next year. It is already being piloted by some community bus systems. Some EV experts believe it will supplant the plug-in chargers in use today.

The technology, which dates to inventors such as Michael Faraday in the 1830s and Nikola Tesla in the early 1900s, uses electromagnetic energy to transmit power between two coils. In wireless vehicle charging, the energy moves from a transmitter coil, encased in a pad that sits on pavement, to a receiver coil housed in a pad underneath a vehicle. On the distant horizon, motorists may be able to get a charge from coils embedded in roadways as they travel along.

"Imagine wireless electric-vehicle charging being as easy and widespread as Wi-Fi is today," said Chris Borroni-Bird, former director of advanced technology vehicle concepts at General Motors and now vice president of strategic development for Qualcomm Technologies Inc., a company investing in wireless charging.

Other companies offering wireless charging include Momentum Dynamics Corp. in Malvern, Pa., outside Philadelphia; WiTricity Corp. in Watertown, Mass.; and Wireless Advanced Vehicle Electrification in Salt Lake City.

Mercedes-Benz has said it will offer wireless charging in 2017 on the face-lifted S500e plug-in hybrid sedan. And BMW, working in partnership with Mercedes-Benz on the technology, is developing a wireless charging system for its i3 electric vehicle and i8 plug-in hybrid. A prototype test version, developed by Qualcomm, is already in use on the BMW i8 safety car in the Formula E electric-vehicle race series. Other carmakers are working to make the technology available, likely for the 2020 model year.

"Every carmaker, and I say that meaning every carmaker, has an active program at some stage of maturity to introduce vehicles with wireless charging," said David Schatz, vice president of sales and business development at WiTricity. "Other carmakers include Nissan, Honda, Toyota, Ford, just to name a few."

Even as carmakers invest millions to develop new EV models, EV market share remains stubbornly stuck in the single digits.

"Automakers know the key to increased EV sales is to improve the charging or fueling experience," said Andrew Daga, CEO of Momentum Dynamics. "They want to get inductive charging into the market as fast as possible."

Proponents say wireless charging will play a key role in autonomous vehicles as urban transportation infrastructures become connected and smart.

"If you have autonomous vehicles you have to be looking at this," said Tony Posawatz, former vehicle line director for the Chevrolet Volt and now a consultant to a number of automotive and technology companies. "You can't have a bunch of autonomous vehicles with guys waiting for cords."

Daga agrees. "You don't need to think about charging at all," he said. "The charging happens in the background, and the payment happens in the background. The whole paradigm of fueling is changing and is going to become autonomous."

That's because, disconnected from plugs and wires, charging will become "opportunistic." Instead of having to get out and plug in, EV drivers will be able to top up mileage as they go about their daily business by parking over electromagnetic charging pads either on the pavement or embedded in it.

Charging pads are likely to appear first in home garages, much the same as plug-in charging stations did. They'll pair with a wall unit, such as BMW's i Wallbox prototype, and a cord that runs to the primary pad on the floor.

"Home units will be priced on par with plug-in charging equipment," Daga said. "If you're going to buy a home charger that's inductive, you're going to be paying less than $1,500 for an 11-kilowatt charger." Such a charger would be capable of charging a Nissan Leaf to 80 percent in 30 minutes and a full charge in two hours.

A company called EVAtran already offers aftermarket wireless charging units for the first-generation Chevrolet Volt ($1,260), Nissan Leaf ($1,540) and Cadillac ELR ($1,940). Kits for the second-generation Volt and Tesla Model S are on the way. The EVAtran website says the adapter kits do not void the vehicle's warranty.

Experts predict more powerful wireless stations later will appear at office buildings, shopping centers and restaurants, enabling EVs to quickly top up. But pricing will be key, says Lisa Jerram, an analyst at Navigant Research. "Most people don't find it that difficult to plug in," she said. Wireless charging "would have to be priced attractively. It's convenient, but not really a necessity."

There's also a debate about whether wireless charging is as efficient as wired charging.

Chuck Caisley, vice president of marketing and public affairs for KCP&L, says the new technology needs to mature. Kansas City Power & Light Co., a regional electric utility, believes there's plenty of life left in plug-in networks. KCP&L has been one of the most aggressive utilities in the country in installing an EV charging network, building more than 1,000 plug-in stations.

"It's more expensive to put into a car," he said of wireless charging. "It is not as efficient as plug-in charging." He said some models arriving in 2018 that will offer a wireless charging option will also be equipped with a plug-in connector.

But consultant Posawatz says wireless can be just as fast and efficient, providing the technology is correctly aligned.

Wireless charging is gaining some acceptance among urban bus authorities around the country. By permitting short-haul buses to top up with power frequently, the bus companies are saving hundreds of thousands of dollars because they can use smaller batteries. (See story, Page 26.)

Initially, charging will be static, meaning a vehicle will have to be parked to charge up. But so-called dynamic charging, where moving vehicles can get a charge by driving over transmitter coils embedded in the roadway, is on the horizon, likely appearing first on buses or delivery trucks running on fixed routes.

The basic wireless charging system uses two coils. The primary coil, encased in a pad that sits on the floor of a garage or parking structure, is connected to a power source. Alternating current flows from an outlet into the coil, creating an electromagnetic field that enables the power to jump to a secondary coil in a pad attached to the bottom of the vehicle. When the vehicle parks in the proper position over the primary coil, an indicator light goes on and charging begins. The two coils must be within about 8 inches of each other for effective charging, according to Daga. 

Plug-in charging has been an obstacle to electric-vehicle ownership for many consumers.

Said Qualcomm's Borroni-Bird: "Even for short trips, we find people with electric vehicles just park the car for half an hour and often don't bother plugging in. If you do that several times, the battery drains significantly."

Plug-in stations also can be easily damaged in crowded cities. A number of municipalities have reported thieves have cut EV charging cables to steal the copper from the wires. High-powered Level 3 stations, also called DC fast-charge, have large cables, which make them even more attractive to thieves.

"Copper theft of charging stations has increased, and the stations remain energized after the cables have been severed," which can pose a danger to the public, according to PropertyCasualty360, an insurance industry publication.

Said Daga: "With wireless, there is nothing to cut, nothing to break. You can hit it with a baseball bat and not break it. It is designed to be driven over by a heavy truck. The lifetime of our units for buses is 20 years."

With all its promise, wireless charging faces hurdles. It means adding another layer of infrastructure to an already complicated EV landscape. Prospective EV buyers worry that there aren't enough plug-in stations. Charging pads will be even scarcer, at least initially.

One major issue -- automakers, suppliers and wireless companies have not yet reached agreement on a compatible standard that would be "interoperable" everywhere. It's a problem that hobbled the rollout of plug-in charging.

Said WiTricity's Schatz: "If you're aware of wired charging history, you know that it was not so well done. They ended up with multiple connector standards depending on where you live."

Last year, engineering trade group SAE International issued a wireless charging standard called SAE TIR J2954. The standard is undergoing testing but has not been adopted. Daga, of Momentum Dynamics, believes the process could move faster if technology providers work directly with Tier 1 suppliers and automakers.

Posawatz says it's difficult to arrive at a standard before the technology gets tested in real-world conditions. "There hasn't been one unit working in a volume commercial environment yet," he said. "But a lot of people believe there's a lot of upside in this space. That's why there's a lot of jockeying."

Navigant Research's Jerram said wireless charging won't replace plug-in arrangements in the near term: "The automakers have to incorporate this in the vehicles. That's a multiyear process. It probably won't be until about 2018 until we start seeing them in large numbers of vehicles."

Even then, it's likely that plug-in and wireless systems would coexist for some time.

Said KCP&L's Caisley: "The moral of the story here is: If you think about cellphones, you can charge many of them wirelessly. Yet every single cellphone by every manufacturer also comes with a plug."