Charging an EV is much like plugging in a vacuum cleaner. You’re making a direct electrical connection between the charger and the EV itself. The cables are chunkier, and the power delivery much higher, and there are more safety mechanisms in place, but it’s fundamentally the same thing. But what if you could eliminate the cables, and do it wirelessly? And fast, too?
Enter the Oak Ridge National Laboratory. Perhaps most famous for its nuclear science programs, it also plays host to a dedicated group of energy researchers. Recently, they’ve been tackling wireless charging for EVs, and 2024 has apparently been a grand year for breakthroughs.
Last month the lab announced that it had smashed a world record, working in partnership with Volkswagen to master wireless charging technology. The team managed to charge a Porsche Taycan at 270 kW—completely wirelessly, with no cable connection at all.
Have a look:
Big Power
The basic concept is not dissimilar to how wireless charging works for devices like mobile phones. A great deal of power is fed into a set of coils, and this energy is picked up by a corresponding set of coils in the vehicle. Power is transferred via magnetic field, allowing transmission over short distances without wires. [Ed Note: Simply put, an alternating current flowing through an induction coil creates a changing magnetic field (also called a “B-field”), and if you put a different coil (like one attached to a car battery) in that B-field, the first coil’s magnetic field induces a current in the car’s coil, charging the battery. -DT].
This work has been ongoing for years, but it’s picked up to a rapid pace of late. In 2016, researchers were wirelessly charging a Toyota RAV4 at just 20 kW. By 2018, the group had achieved 120 kW charging with conventional coils. However, these had limitations around size—and thus, power density. Fast forward to March this year, and the research group had a fancy new polyphase coil design that reached power densities eight to 10 times higher than regular coils. The team hit a milestone of 100 kW charging at 96% efficiency with this new hardware (a big deal, since efficiency is often seen as a major drawback of wireless charging). Work continued, and the new design was pushed to new limits, hitting 270 kW in June.
Those special polyphase coils are the key to the whole thing. A wireless charging system using traditional coils would be too heavy and impractical to fit to a typical consumer EV like the Porsche Taycan. However, the lightweight polyphase coils use advanced geometry to up the power density to the point where only a 19-inch diameter coil is needed on the vehicle.
270 kW is seriously fast charging, no matter which way you slice it. This power level can be sustained over an air gap of 4.75 inches, with the receiving coil mounted on the underside of the vehicle. ORNL notes that its system can achieve a 50% increase in the vehicle’s state of charge in just 10 minutes.
The aim is to simplify EV charging while making it lightning fast to boot. If such a system became mainstream, you’d simply pull into a charger-equipped parking spot and enable charging. There’d be no need to hook up any cables.
“We’re also working with Volkswagen on developing a polyphase system for residential charging applications and collaborating on the development of a lightweight enclosure design that will improve mechanical, electrical, thermal and magnetic performance,” said Omar Onar, ORNL’s power electronics research lead. “Our goal is to mature the technology so that it’s ready for deployment in production vehicles.”
But Why?
It’s hard to top the efficiency of a direct wired connection. It’s true that the ORNL technology gets close, but even then, it’s perhaps difficult to see a path to implementation for this technology.
Wireless charging has one major benefit. You don’t have to hook up a cable. That’s kind of… it. It’s not more efficient, it’s not faster, and it’s not likely to be cheaper. It’s more convenient, in theory, but that might not be enough to get it into production. As much as some of us resent having to get out of a warm car to unplug a charger, it’s not that big a deal, right?
In the dark days before widespread EV adoption, it’s true that there were some safety fears around charging. Automakers explored inductive and wireless charging methods for early EVs, with the GM EV1 being a great example of the technology. There were safety concerns around using high-voltage, high-power connectors, as well as questions around wear and longevity. Ultimately, though, smart electronics in modern chargers and robust connector designs largely solved those problems. Today, people charge their EVs every day with direct metal-on-metal charger connectors without issue.
There’s also the same old infrastructure problem to be considered. Over the last decade, great effort has been spent installing conventional chargers across the US, and across the world. America is now going through some further pain as everyone deals with the switchover to NACS. The thing is, pretty much everyone is finally on the same page. The US will have a given charger standard, and that’s it.
Ring up an auto executive and say you want them to put wireless chargers on their cars. Are they gonna be keen to jump right into that? There are presently no wireless chargers out there and it’s a whole lot of fuss for only nominal benefits.
That’s not to say it won’t become a thing. Wireless charging could become a luxury feature that separates the finest EVs from the economy models. Of course, charging installations would have to equip themselves with the appropriate wireless coils in turn. But that could be the way it goes—that wireless charging becomes the premium option, with spendier users paying for the gradual rollout.
Obviously, Oak Ridge isn’t the only lab in town in this regard. Other automakers and researchers are chasing the same goal of wireless EV charging—some even contemplating how to make it work on the move. Whether it becomes a reality is another thing entirely, though.
Ultimately, the researchers at Oak Ridge have achieved a great feat. All that lies ahead is the mountain of work to turn a working lab project into a viable commercial product. History tells us that’s never easy, even for the most promising tech. Are enough customers dying for wireless charging to make it a commercial reality? That remains to be seen.
Image credits: Oak Ridge National Laboratory, Oak Ridge National Laboratory via YouTube screenshot, Stephan Schwebe via Unsplash license, Hyundai
Ultimately, this will lead to electrified highways and lighter EVs with smaller batteries, resulting in greater efficiency, performance and handling.
We could have actual autonomous vehicles (in certain conditions) if we put nails down in the roadway. That would be too much infrastructure investment. There’s no way the US is going to install wireless chargers in public roadways.
In the north, they’d be taken out by snow plows their first winter – never to be repaired.
There is a financial incentive to build and maintain an electrified highway. It’s not going to happen tomorrow, but I believe it will happen. I don’t know if it would be strictly a government infrastructure project either. The potential to fuel millions of cars and trucks is powerful.
Eisenhower built the Interstate Highway System in 1956 (or so). We built the atom bomb and subsequently nuclear power in WWII – though building the B29 bomber reportedly cost more. And we – the US – built the Hoover Dam and a bunch of other dams, starting in the Depression era of the 1930s. These dams lit America without carbon emissions while pissing off all manner of environmentalists – go figure.
Anyway, the United States is no stranger to mega-engineering projects and if the technology gets right, and the will to build is there, electrified highways could supercharge the American economy. Not to mention it would help with our environmental issues.
Much of that 70 year old highway system hasn’t been maintained in 40 years, as shown in crumbling bridges.
The last thing this nation ‘built’ was the TSA.
I’m also not sure what would be the point of charging on the go. If there’s enough battery for a full driving stint, that’s really all you need. Truckers are obligated to stop for rest breaks and I know I’m ready for a wander around the truck stop after 300 miles in a car.
If we want to electrify, we already have something that works. Overhead wires work, and they’re absolutely less expensive to install than these things.
Electric cars, in their current iteration, offer certain utility. But an EV with half the on-board battery – or less – would be cheaper and faster. With in-road charging, the problem of slow refueling would also be eliminated. Finally, in road charging also could be integrated with autonomous vehicle strategies.
I’m sure overhead wires work. They work for trolley cars. But the problem with overhead wires is that – They’re wires.
I don’t have all the answers, but wrote a paper on the idea of wireless in-road EV charging for an MBA class about 30 years ago. You (I) can make a compelling argument for in-road charging. It’s all science fiction now, but I am championing the idea.
It very much will not. It may lead to electrified parking spots at truck depot, storage yards, and luxury homes, but anything that increases the cost per mile of a road is a nonstarter.
Could be useful for electric semi trucks, takes away the need for charging bays and poles. Federal regulations have them stuck in the same spot for hours anyway.
But even a slight loss in efficiency will make a huge difference when you are getting close to a Mw/h.
You mean like this?
https://www.youtube.com/watch?v=mBwvQwzBxjk
but that cuts into the business of selling batteries
It is a huge deal if it works right. One of the big problems with wired chargers are the wires, people cut the cords to sell them for scrap. I’ve seen too many stations that are out of order because the cords were stolen and I only expect that to get worse over time. So yeah not having a cord to steal is a big deal.
There are charging cables on the street in front of my work in Downtown LA that get cut almost every night.
Biggest benefit is for driverless cars like Zoox or Waymo. No more humans needed.
The goal is to no longer need humans in any capacity. They are slow, inaccurate, and need up to 30% of operational downtime for energy regeneration.
Given how little wireless phone charging seems to work I doubt wireless car charging is going to be much of a thing anytime soon. How about just connecting on building a reliable charging network for now?
I’m very curious about this. I’ve been wireless my charging my phones and other devices when I can since roughly 2017 almost exclusively. It seemed a great way to get around the micro USB and lightning plug or cable degrading over time problem. As a bonus I chose 5w chargers so it prolongs the battery longevity by not being able to charge too fast.
My personal experience has been I can count on wireless working roughly 3x as often as using a cable. Granted, USB c is way better, but I’m starting to get worried about my laptop now after roughly 500 connect disconnect cycles to a charger per year for over 2 years. I’m at the point now where it doesn’t charge roughly every 2 months and I usually notice it when I get a warning I have 20% left.
I’m prepared to be corrected, and I’ll try to find more info, but I’m calling BS on 96% efficiency.
Researchers love to quote high metrics, while also defining a generous metric.
This could be 96% of the power in the B-field. (Ignoring generation and propagation losses, and assuming ideal receiver alignment) Or 96% of current in the coil, or any number of ways to define the “input”.
If it’s truly wall plug to battery I would be astounded.
Betcha It’s coil to coil ignoring all other losses.
Even at 96% efficiency, that 4% represents a LOT of wasted energy in this application, like 1.9 kWh wasted bringing that Taycan up 50%.
That waste alone would get my wife half way to work.