Is Wireless The Future For EV Charging?

Imagine a future where you drive your electric car to work, park, get out and walk away, and your car automatically starts recharging via a wireless connection. Such technology is being developed by a company called Evatran LLC, whose Plugless Power product should allow you to do just that.

Since Google has installed and is testing this product for its own electric vehicles (EVs), wireless recharging likely has a viable future as part of  the EV power-supply infrastructure. The system works by using inductive power transfer. This in itself is not new technology - Evatran explains it uses the 100 year old principle of electrical induction. In brief, it works like this:  In order to effect wireless charging, you have a transmitter coil and a receiving coil, separated by a distance. An electrical current passed through the transmitter coil produces a magnetic field that induces a voltage in the receiving coil. The voltage created in the receiving coil, in this application, recharges the car battery. Seems an elegant enough solution, but what are the benefits to the consumer?

First of all, the so called proximity charging system is convenient. After a special adapter is fitted to the car (which includes the receiving coil), the driver simply parks over the floor mounted 'parking block' (which houses the transmitter coil), and the system automatically starts charging. What you have is a simple hands-free set up which involves no cold, wet, dirty cables. Second, the system is universal, as the car-installed adapter works with any type of electric vehicle. It can adapt to vehicle-specific voltages, which eradicates the problem of non-standard connectors and plugs. Thirdly, the manufacturer claims it's reliable, and since no electricity is flowing between the car and the floor (only a magnetic field), it's safe. It's also probably less prone to damage and vandalism than a cable based system.

Where the system has a downside however is in efficiency. Inductive power transfer suffers energy losses, which in this case would be dependent, in part, upon the distance between the car and the floor mounted parking block. Though Evatran claims that the system is 90% efficient, cable based power supplies that we see in use today, most likely have the efficiency advantage.

The user convenience, however,  is no doubt compelling from a business standpoint, as the mass adoption of EVs will likely depend in large measure on ensuring user interfaces are kept as simple as possible. But with power generation most often from dirty sources in the first place, coupled with the energy loss in transmission, is further energy loss in the last few inches to get to the car a justifiable cost for convenience? A stretched electricity grid probably doesn't need further inefficiency, but this system nonetheless seems to be another innovation that might perhaps help sell the electric car to a wider audience.