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
I wonder if there could be a benefit to installing these in high-traffic areas. Yes, it would be nice to charge as you’re rolling down the road, but that seems prohibitively expensive and complex. But, what if they were installed within the first few hundred feet of an intersection so the car can charge while you wait for the light to change? Or a drive-thru lane? Given how many people I see at Starbucks, you could go from 20% to 80% while waiting for your PSL.
that would actually be amazing. “ugh, KFC is slow today, but I’m getting plenty of juice.”
Somebody’s gotta pay for that energy. Whether by raising prices, or raising taxes, or a way to ID each vehicle that charges.
EVs are somehow a political thing, so expensive infrastructure to support them is not getting funded.
No. Just… no.
And for specific reason why, we have roads that are made of layers of compacted dirt, compacted gravel, compacted asphalt, tar, and paint. None of these things are very expensive, they all last a fair bit of time, and you can extend the longevity of a road with patching and crack-filling. People don’t like losing access to their roads, especially access to a high-traffic road.
If you start installing terrible ideas with unsound engineering (like solar roads, or induction coils, or WiFi, or whatever else your pipe dream is), then you have now turned a fairly low-maintenance proposition into one that either (A) will fail and never be fixed or (B) require annoying vast swaths of people when you need to turn off the road function of the road (namely, by closing it) to fix the other function you foolishly installed.
Roads need to be roads. If you want other stuff – solar, wifi, wireless charging, etc. – do those somewhere that isn’t a road and where maintenance can be conducted without hampering the primary function of the road.
If this takes off then you will never need to worry about an empty EV again. You could embed these things anywhere and everywhere. You could subscribe to plan that lets you charge whenever. The price would come down at scale, and maybe someday we would have freeway lanes that charged you as you went. This would have the benefit of not needing huge advances in battery tech to extend the range of EVs to what would essentially be unlimited.
I was also skeptical of wireless charging until I got one for my phone. Never underestimate the selling points of convienience. Pulling onto your driveway and walking straight into your house is a big deal. Whenever I’m in Germany Im borrowing an EV. Yes, hooking it up when I get to where I’m staying is quick, but it isn’t instant. I still need to grab a big ol cable and move it over to the car and plug it in.
I look forward to an easy charging future where the only hassle is having to download the specific app for the charger you’ve parked over and then trust them not to bill you unfairly.
This is a scammers dream, all you need is a sign near a parking space.
The main benefit that I see is that cars have charging ports all over the place, sometimes you have to backup since the cord is no long enough, etc. Having to just park and start charging immediately, would be amazing to me.
I’m assuming that impressive 96% efficiency is very sensitive to alignment. How close is close enough and how bad does the efficiency drop if the two coils aren’t perfectly aligned?
Also, while 96% efficiency is very impressive, it isn’t, to make an obvious point, 100%. A typical EV battery pack is around 100kWh. So a 40% loss is around 4kWh of energy. 4kWh is enough energy to run a typical American house for around 3-4 hours. Multiply this times thousands of EVs, it becomes a lot of power very quickly.
It’s kind of like Covid deaths. I kept hearing “oh, only 1% of people died from it! It isn’t a big deal!” If 1% of people died on a flight in a 747, that means 3 people wouldn’t get off that plane, and you probably wouldn’t want to fly it. “Rounding errors” can become more impactful than you’d think when we’re dealing with big numbers.
Current wired chargers aren’t 100% either – whether it be for your USB-C phone or your EV. 96% is right about what cabled charging is for gadgets – there’s always some parasitic loss along the way in the transformer, the cable itself and what have you. But it’s much better than the ~50% efficiency of wireless gadget chargers.
For EVs the only person I’ve seen talk about efficiency is Harry Metcalf and he claims that there’s a 10% loss, which winds him up as you pay for the full amount but only 90% makes it into the battery. I don’t know how accurate that number is, but it’s certainly not 100% efficiency.
That’s all true, but the wire itself is basically 100% efficiency, save some losses for heat. So any lose for the wireless connection (i.e. 4% here) would be in addition to any loses from the charging circuitry before and after the wireless transfer. That’s why I was using a “100%” baseline for traditional chargers.
I used to be skeptical of wireless charging pads for my phone – the charging cable works just fine, after all – until I read somewhere that wireless charging really starts to make a difference when you’ve got a number of them around your life – by the couch, on the nightstand, on your desk at work – so that you can keep your phone topped up whenever you set it down and thus never have to think about your state of charge.
I see wireless charging for cars having a similar use case. Yes, it’s easy to plug a car in your garage and you’ll charge up overnight. But if I can top up a little at the grocery, and a little more at the library, and a little more at Home Depot, all day long as I go about my day, then range anxiety and charging times occupy less of my brain and subconsciously that’s one less thing to worry about with EVs.
But as far as I understand lithium-ion batteries don’t actually appreciate constantly being recharged all that much. Keeping them >90% charge, for example, hastens capacity loss according to wikipedia and I’ve repeatedly seen the advice to keep charge state between 15 and 80%.
Not that that completely negates the point you’re making but it does add another thing to juggle.
Set the state of charge lower. The car won’t charge past that. All it will do is use some minimal energy to keep the computers on and possibly precondition.
EV batteries are typically already spec’d with 20% off the top to account for that. That’s why they say “usable capacity”. When it’s charged to 100% it’s only about 80% in reality.
What happens if a person stands on one of those while it’s active? A person with a pacemaker? A baby in a metal stroller or granny using a metal walker?
I would imaging there isn’t a situation possible where it’s just on and there not being an actual compatible receiver vehicle charging just above it, just like regular wireless charging now.
Well except when the computer glitches or a relay is stuck or the thing was just built by the cheapest bidder. If it can go wrong it eventually will.
they can’t just get stuck on if the receiver coil isn’t right there.
wait, why not? A coil is just a length of wire with electricity flowing through it, whether there is anything in its magnetic field or not
it’s not just wires with high rate electricity constantly flowing through it. just like regular charging, the device that needs the charge is what is “asking” for the power to start being delivered at a certain level.
Oh yeah I mean I understand they’re not constantly “on” but only on demand. But what’s to stop the computer controlling flow to the charging coil from having a crowdstrike moment and deciding that there is, in fact, a need to power the coil now? Or the switch that toggles power flow from getting stuck in the open position?
granted these things might work differently for some reason, but that isn’t how it works with charging now, if nothing is there it isn’t going to get stuck on like that.
So with some cursory googling I sadly wasn’t able to find much data on whether or not wireless phone chargers are significantly more dangerous than wired chargers, but I did find that there seems to be at least one way to hack charger-phone communications in a way that can cause a phone to overheat and possibly catch on fire. If that can happen by intentional sabotage, then it can happen by accident, too.
From an article over at “techradar”
Perfect use case for this meme: https://imgflip.com/i/8yrvaq
I can only imagine how long the BMW engine splash shield will last with this thing hanging off it and only those little clips to hold the thing on…
I’m sure it had to be a Taycan. You know, for National Security purposes. Yeah, national security. And naturally, statistical rigor is paramount in ANY experiment, so they’ll need to discharge the battery a bunch so they can recharge it. Oh, and of course, they need to control for the driver as a potential variable as well.
hahah, I thought the same thing.
“Oh, Taycan, eh? Yeah, I guess there’s no way you could have done this with an ID.4…”
At the same time… I guess it’s lower to the ground. That helps with the coil spacing.
I hope it works better than all the wireless phone charging I’ve encountered
I was also skeptical at first, but I’ve been using a couple for several years through two phones now and haven’t had any issues with either of them.
I’ve found its a great way to charge my phone 2-3% while also making it the temperature of the sun
I’d like to know how much stray magnetic field there is, and if it presents any danger if there is ferromagnetic FOD nearby.
Exactly my thoughts. This could be like parking in an MRI.
A three-phase design like that will keep the magnetic field pretty well contained since the net flux through the apparatus is zero. But anything directly between the transmitter and receiver would be toast.
Hope the dropped phone doesn’t bounce under the car while it’s charging!
I can definitely see a use for this with regard to disabled drivers. Also, from a security standpoint, you can stay in your locked vehicle, more secure from potential predators that tend to lurk around places like charging stations and ATMs.
Yeah. I know some people find being stuck to a charger terrifying… some dark stories from Supercharger users. They’d appreciate this for sure.
That’s fluxed up.
While I mostly agree with the premise of the article that this is a solution in search of a problem, I do see a specific scenario where this would be unbelievably useful, but likely too expensive to even consider implementing.
Around where I live the only parking you’ll be able to find is parallel parking on a one way street hopefully within a block or two of where you live. To me this makes an EV a non-starter for the large majority of people that don’t have a garage they can plug in at. If the city could install one of these base stations every 15′ wherever there’s parking it would make urban EV ownership turn from a nightmare to a dream. Of course you’d need to figure out a payment system that works across vehicle manufacturers, cars would need to be fitted with a receiving coil roughly every 2 feet, and this would cost an insane amount to implement, but it sure would be nice.
For sure. If paid parking spaces had these built in, there is a huge use case for them. Imagine paid parking spaces where you pay for the spot, and at the end, you pay for the time there and the energy used. Parking spaces like that seem to be a very good use case.
You’re right, I didn’t think of that. This would be brilliant for side-of-street parking.
great, now instead of catalytic converters, thieves will start cutting the wireless coils out of your EV.
F-Zero is coming to life!
A benefit that I can see here is the potential to reduce damage to chargers. It’s a lot harder to take a jackhammer and get the copper out of a charging pad than to cut a cable. People won’t be stretching cables every which way to make them work, twisting, pulling, and scraping. And people won’t be plugging/unplugging over and over, potentially wearing out connectors and latches.
That said, I assume the wireless charging would be expensive. And there is the potential for weather-related damage. But I can see a case for it. And if the inefficiency is properly managed, I could see this also helping prevent ice buildup in parking spaces in the winter.
That’s actually wildly important given the number of cables that are regularly cut or damaged, and obviates any worry about the cable being the correct length for the charge port.
Or the charger deciding to LOCK the connector onto your car and leave you stuck, trapped at the charger.
This is a huge deal. Can you imagine if this becomes stable and widespread? You could put these just about anywhere and have people just park and charge. If there are enough, you wouldn’t even have to think about fueling anymore. Park for lunch, pick up 20% range, drive on to your next stop.
The main problem I see is that this is still going to be hugely inefficient and generate a lot of heat.
Still, this is going to be a big deal if it can be commercialized and made ubiquitous like Qi.
I can see a bunch of jealous truck bros and MAGA hats parking on wireless chargers just to be obnoxious.
Trick them on and they’ll regret it. Zapping a bro-dozer’s wiring harness and ECU will be a deterrent.
I love that idea. But like nuclear energy being too cheap to meter… I don’t know that I see it happening.
Could this be the solution to charging large vehicles or trailers that don’t fit into normal charging spots?
More to the point, every parking spot could have one and it would not really matter if you aligned the charging cord with the charging port location…since, you know wireless.
If they can get the cost down where equipping every spot can be reasonable, obviously that would be awesome.
If it stays relatively expensive and limited availability, I’m just speculating on a high value place to start.
That would make electric pickup trucks more practical towing vehicles. It’s not a big deal to drop and re-hook a 15′ camper every couple hours to charge. It’s a much bigger deal with larger trailers.
Hopefully it could be scaled up to a freeway lane with this embedded in the surface to enhance self driving from sensing the field while also increasing range without requiring bev’s to stop and charge.
Honestly, I think an overhead wire à la trolleys and trains is probably a better choice for installation, maintenance, and alignment in that regard.
They are at least piloting this. I’m sure it’s wildly expensive, but could be awesome someday: https://www.michigan.gov/mdot/travel/mobility/initiatives/wireless-charging-roadway
I don’t see any mention of the alignment accuracy needed for the latest version to work. If the car needs to be aligned with the charging pad to within an inch or less in precision for it to work, then that would be far more difficult than plugging in a cord. It might require the car to park itself in the correct position, which would need further sensors, controls, and such.
From another practical standpoint, it also requires parking in the same place all the time. We’ll park our car in different spots in the driveway, depending on if we want easy access to the garage and such, and it’s easy for the charge cord to reach the different spots, which wouldn’t work with a fixed charging pad.
I’m totally ignorant about wireless car charging, so this question is floating around my head. What is the volume of electricity loss because of the 5″ gap between the car and charger? Or, do the electrons stay in path and moving because of the magnetic field?
I really should have been better at math and learned more science based things in high school and college!
This is a good question and a totally reasonable one for any person who hasn’t studied much or any physics. I’m sure plenty others wonder the same thing. The short answer is that there are no electrons moving from the charger to the car. More detailed answer below:
As mentioned in the article, wireless charging takes advantage of the physics that relate electricity to magnetism. A changing electric field can induce a magnetic field, while a changing magnetic field can induce an electric field. The charger generates a magnetic field which is then received by the car and converted back to an electric field. See this image for more: https://cdn.shopify.com/s/files/1/1384/0075/files/blog-large-2.png?
Thank you, AJ. I feel less stupid today than yesterday. ????
🙂 Progress!
You could make the same argument about your phone, but nowadays people demand wireless charging, android auto, and carplay. I get that replacing these chargers are more expensive than buying a wireless charging pad, but the reward is also greater. If I can get 50% in 10 minutes and am low on charge in a rain storm, with this I can just pull into a parking spot, hang out for 10 minutes, and get home. All without getting out in the rain.
The big draw is more on roads and charge-as-you-drive, although given the current copper thefts, induction charging might gain more traction for parked charging.
Could you fry a Qi-charging device if you put it on top of one of these coils?
It’ll charge your phone in ten seconds, flat!
Very cool, and would a big step forward to removing the headaches of multiple charging standards. My question would be how much of a safety hazard is that charger? I would guess it’s driving a fairly strong magnetic field to be able to pump out 270 kW, and that could cause some issues with say, pacemakers, or any loose ferrous material that might be on the bottom of the car.