There's been a lot of talking about wireless charging for electric cars recently.
The convenience of being able to charge without plugging in may well appeal to buyers who, for whatever reasons, find plugging in a car to be an impediment.
But while several companies are pursuing the technology, it isn't currently available from automakers in new cars.
The Society of Automotive Engineers (SAE) has been working to lay the groundwork for a single, unified standard for wireless charging.
A few years ago, the SAE issued the J1772 standard for 240-volt Level 2 AC charge connectors, and now it has a set of guidelines for wireless charging.
Known as SAE TIR J2954, the guidelines were issued with the goal of standardizing wireless-charging equipment for future electric cars.
BMW, Mercedes-Benz working on wireless charging
SAE officials hope this will lead to interoperability between cars or charging stations from different manufacturers, and the attainment of certain performance standards.
The guidelines set safety and efficiency targets, and define the parameters of certain components.
They also establish a common frequency band in the 85-kilohertz range for all light-duty-vehicle wireless-charging systems, as well as four power levels.
Those include 3.7 kilowatts, 7.7 kW, 11 kW, and 22 kW, and may be augmented with higher power levels in the future.
Carmakers and suppliers have built J2954-compatible systems that are now being tested by the U.S. Department of Energy at the Argonne and Idaho National Laboratories.
Data from these tests will be used to create final standards that will be issued in 2018.
BMW i8 Formula E pace car
By then, carmakers may be ready to include wireless charging on their new vehicles.
Nissan began testing wireless charging last year, but hasn't committed to a production timeline yet.
And several other carmakers have promised to include wireless charging in future electric models, without committing to specific timetables.
The 2017 Mercedes-Benz S 550e plug-in hybrid is rumored to be in line for wireless charging, although Mercedes hasn't officially confirmed that.
The BMW i8 pace car for the Formula E electric-car racing series actually have wireless-charging capability, thanks to hardware supplied by Qualcomm.
BMW hasn't said whether that feature will be added to the production i8, though.