How will Wireless Charging technology fit in with Electric Vehicles?

Tuesday, September 1, 2009
The idea of wirelessly transmitting power has been around for over a century, thanks to Nikola Tesla.  Back in 1893, Tesla first demonstrated to the world the ability to wirelessly illuminate phosphorescent lamps at the Chicago World’s Fair.  Since then, the technology has been slowly maturing in research facilities. 

One notable large scale demonstration of the technology was made in NASA’s JPL/Goldstone facility.  Back in 1975, NASA demonstrated that it could effectively transfer 34KW of power across 1.5 KM at 82% efficiency…very cool stuff, especially back then. You can see the test in the video here:

The focus of using wireless power transfer over the last 10 years has been charging small devices like your cell phone or wireless headset directly on a charging pad (e.g.  However, a company in Massachusetts called is gunning for applications that are separated by a few feet…and one of their applications is charging electric vehicles!  The video shows WiTricity’s CEO, Eric Giler, at a TED Conference showing off his cool technology.

Even Nissan, who has announced a bold strategy to concentrate on EVs has announced that they are actively working on a Wireless Charging technology.  Read about it here at the Guardian.

Considering what I know about the technology today, I see the following opportunities and challenges for charging wirelessly…

  • Convenience, just drive up and charge!  Whether it’s in your garage, at a traffic light, or on one of our city roads that becomes a parking lot during drive time commute, you wouldn’t have to do anything to get a charge.  Very cool!  Don’t be surprised to see this convenience depicted in a SciFi movie soon.
  • Could be integrated with Smart Grid.  Like other network level chargers, this technology could be integrated into the Smart Grid to provide utility control and accounting of how much charge and which vehicle got the juice…all automatically.
  • For charging vehicles at Apartment Buildings or Public Areas, wireless charging has these additional benefits...
    - No cords to wear out (it's built into the street, parking place, etc)
    - No cords to vandalize
    - Park and charge in bad weather (don't have to take the time to plug/unplug if it's raining/snowing/etc.)
    - Ensures the charge power is used for a specific device (vehicle with receiving antenna)

  • Efficiency: To get high efficiency out of wireless charging, the receiving device either needs to be very close to the transmitter and/or the transmitter must be able to focus the energy directly on the receiving device.  WiTricity is claiming 50%+ efficiency now for close distance charging and NASA saw 82% efficiency from the JPL experiment, so it’s possible that this might not be a limiting issue.
  • Cost: While the technology might be cheap to produce, how much to install this technology in roads, garages, and vehicles?  This includes routing power cables to transmitters.
  • Standards: Technology like this must be standardized to be widely adopted…especially considering the potential installation costs.  
  • Power Scale/Charge Time: Most of the companies today have demonstrated wireless power transfer of just a few watts.  Will the technology be able scale up to pump 7,000 W (Level 2) into your vehicle so it can charge quickly?
  • Value: Assuming Corded Power is 100% efficient, will the cost of the technology, installation, and the inefficiencies to wirelessly transmit power be worth the inconvenience of plugging in your vehicle?  For instance, if the technology is only 50% efficient, then you’d be paying double to power your vehicle wirelessly…is it worth it?
You can find a few companies making wireless charging systems for EVs on my EVSE Vendor Page.