SAE International Announces Agreement On Wireless Power Transfer Frequency For EVs

NOV 20 2013 BY MARK KANE 19

WiTricity Wireless Charging

Wireless Charging

Wireless Charging Unit

Wireless Charging Unit

After three years of work, the SAE International J2954™ Task Force for Wireless Power Transfer (WPT) of Light Duty, Electric and Plug-in Electric Vehicles has finally announced that it will shorten its name OEMs, WPT Suppliers, industry experts and government representatives who make up the Task Force agreed upon two key factors for the Technical Information Report (TIR) on interoperability for the first phase of pre-commercial development.

First is the frequency at which power transfer will be done in wireless charging – 85 kHz nominal.

Jesse Schneider, Chair J2954 Taskforce, said:

“A common frequency of operation for WPT is essential for interoperability. After 3 years of international collaboration and investigation within the team, consensus had been reached on a nominal frequency of operation for the light duty vehicle guideline. The SAE team has determined this nominal frequency of 85 kHz for SAE J2954. This frequency lies within an internationally available “frequency band.”

This 85 kHz frequency is within an internationally available (81.38 – 90.00) kHz band.

We can assume that different manufacturers developed to date devices with different frequencies and that this SAE agreement is some kind of milestone.

The second big thing is that the SAE determined three power classes for light duty vehicles, WPT 1, 2 and 3.  Limits are defined by the maximum input Wireless Power Transfer:

SAE TIR J2954™ WPT Power Class
Private/Public Parking L.D. Fast Charge
Maximum Input WPT Power Rating3.7 kW7.7kW22 kW

No word on fast wireless charging with power levels of over 100 kW – sometimes used in buses.

Whats next? The Task Force plans to complete the TIR in early 2014. The SAE Technical Information Report will be followed by publication of SAE J2954™ Standard, based on field data confirmation.

“The SAE International Task Force is currently working on completing the remaining interoperability topics, including factors such as the minimum coupling factor “k”, alignment, and coil geometries.”

Categories: Charging


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19 Comments on "SAE International Announces Agreement On Wireless Power Transfer Frequency For EVs"

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Maybe the road to uniform wireless charging will be more straightforward than I expected…

Pigs might also fly
Doing a charge plug well is not a hard thing to do yet look at Chademo. Only the people who brought you fukushima could mess that up that badly.
Wireless charging for a car has a lot of choices to be made so if they mess up something simple, how can you expect they will conquer something hard..

I figure that for wireless to work the car will probably have to lower the coil down the ground for best contact and it would need the ability to aim. That pretty complex already.
Wireless is a romantic notion but I expect it will die in complexity and mess like hydrogen fuel cell cars.

WTF, that’s why the SAE are working on a standard, because it just doesn’t work!

You are SUCH a troll!

Those Plugless Power pods look like toilet seats/lids: “And this is where my EV goes to the bathroom…” 😉

Have they put limits on harmonic power and side emissions? Have/will the SAE consult with the FCC on this, and specifically apply Code of Federal Regulations, Title 47, Part 15 ?

I cannot un-see the EV toilet lid now. Thanks. 😉

I’ve wondered about the power of the RF emissions myself. 85kHz is a low enough frequency, but how much power can humans tolerate? Have any human tests been done? I’m not talking about microwaving humans (the frequency is far too low for that) but other issues. We are concerned about cell phones in our pockets which emit less than 1W of power. Now we’re talking about up to 22,000W of power.

All because I don’t want to plug in my car? I’ll take the hard-wired plug, please.

85Hz = the brown note (sorry all this talk of toilets made me think of that)


Exactly. Not to mention additional 10-15% loss at wireless charging…

The only place where I can see it is useful is places where it rains a lot and it is located in the public area where people are lazy.

The way I would see this as useful is for public charging combined with the self-driving systems being developed. Imagine your car could auto-valet and charge, then leave the space to allow another vehicle to charge. That seems useful.

For charging in my garage, I am happy to keep the plug.

LOL @ 10% loss. Since it costs me less than $1/day to charge, I’ll pay the extra $36.50/year for the convenience. My time is worth more than that, and I don’t have to fuss w/a wet/dirty/cold cord in the dark. Or a frozen/stuck charge port door that won’t open. Or…

Faster please! 🙂

This is what will sell the oldsters. Just park it and no maintenance. Drive, park, repeat. Full ‘tank’ every time.

Needs to be a larger sedan like an Impala though. Or a small van if they need to take their wheelchair/walker/stuff.

Soccer moms/dads too. Busy parents do not have the luxury to fuss with cords.

Oh yeah. It definitely slows down my day. Or not! My son plugs in the car while I unload the trunk. It’s already far more convenient than “oh shoot, I need to find a gas station” while in a rush to get the kids to school.

Then I guess they don’t have time to deal with gas stations too 😉

As long as this is the ONLY standard, instead of this Chademo/CCS/fast AC stuff we have going on now, then I’m fine with it.

I don’t mind plugging in at home overnight, but I think wireless charging is better for places you stop for shorter periods (2 hours or less) like shopping malls or movie theaters.

Wireless charging will have its place, but probably not in my garage. It is particularly well suited for autonomous cars, though. If they can communicate with one another, they can even form a queue, taking turns charging and then parking when done.

Finally SAE is actually ahead of deployment with the standard. Three years to find a frequency and charge rates seems horribly slow. They will need to move faster to stay ahead of the tech.

No wonder the gas companies are working on automated robotic fueling…. they know wireless charging could tip the scales…


Have any health studies been done on these things? What happens to a small pet “investigating” the transmitter pad? How much side leakage is there? The power density seems rather high.