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.