A standard finished twice, in 2020 and in 2024
A technical standard called SAE J2954 sets the rules for how a car can charge wirelessly, without a plugged in cable, by parking over a pad built into the ground. SAE International, the engineering group that writes the standard, first completed it in October 2020. That version created a power class called WPT3, which allows up to 11 kilowatts to pass from the ground pad to the car, the same power level as a typical plugged in home charger, across a gap of up to 10 inches between the pad and the car. In August 2024, the group finalized a revised version, which adds a system that automatically checks how well the car is lined up with the ground pad, so a driver no longer has to aim the car by eye to charge at full power.
The efficiency figure the standard reaches today
Efficiency measures how much of the power sent into the ground pad actually reaches the car battery, the rest is lost as heat. At the 2024 finalization of the standard, SAE International states the current version reaches up to 93% efficiency, at up to 11 kilowatts. When the standard was first completed in 2020, the task force chair stated an efficiency of up to 94%, a figure the current, revised version has since replaced. No source read for this article states a comparable efficiency figure for a plugged in cable to set against the 93% wireless figure.
Only 1 automaker has a dated commitment to sell it
Porsche is the only automaker found in this research with a named, dated plan to sell a car built to the standard. Its wireless charging system, for the Cayenne Electric, sells at up to 11 kilowatts, matching the power of the plugged in AC charger it already offers, and Porsche states its own system reaches 90% efficiency from the grid to the battery, its own figure for its own product rather than the general figure for the standard. Porsche says 75% of all charging done by its electric vehicles already happens at home, which is why an automatic, no cable system matters to the company. Sales begin in 2026, at Porsche Centres and online, starting in Europe. That is 6 years after the standard the system follows was first completed. Dr. Michael Steiner, deputy chairman and member of the executive board for research and development at Porsche, put the case for it this way.
Ease of use, suitability for everyday use and charging infrastructure are still the decisive factors when it comes to the acceptance of electric mobility.
Dr. Michael Steiner, deputy chairman and member of the executive board for research and development at Porsche. Source 3.
A government laboratory has already gone past what any buyer can order
The Porsche figure is the power level Porsche states for its own product, source 3. The 270 kilowatt figure is a laboratory demonstration by Oak Ridge National Laboratory, source 5, not a system sold in a car.
Show the numbers
| SAE J2954 standard, WPT3 class maximum | 11 |
| Porsche Cayenne Electric, on sale 2026 | 11 |
| Oak Ridge National Laboratory, laboratory record, 2024 | 270 |
Separately from any car on sale, the Oak Ridge National Laboratory, a United States Department of Energy laboratory, has spent years pushing wireless charging power far beyond what the standard covers. It delivered 20 kilowatts wirelessly to a vehicle in 2016. In 2018 it reached 120 kilowatts in a benchtop laboratory test, not on a moving vehicle. In 2024, working with Volkswagen Group of America, it delivered 270 kilowatts wirelessly to a real Porsche Taycan, at a stated efficiency of over 95%, across a smaller gap of 4.75 inches, adding 50% of the battery charge in 10 minutes. The laboratory says the coil it built into the vehicle for that demonstration packs 8 to 10 times more power into the same amount of space as the coils used in existing wireless charging systems.
The 2018 figure was a benchtop laboratory test, not delivered to a moving vehicle. The 2016 and 2024 figures were delivered to a vehicle, a Porsche Taycan in 2024.
Show the numbers
| 2016 | 20 |
| 2018, benchtop test | 120 |
| 2024, on a vehicle | 270 |