Most of us take for granted being able to toss our phones onto a charging pad to top them up, but what if we could charge our cars the same way? No more remembering to plug in your EV when you arrive at work or get home. Without having to even think about it, your car would always be charged up and ready to go. At the beginning of 2020 I spoke to a company that’s leading the charge in wireless electric vehicle charging and I thought it was time to revisit the topic to see where things stand … and even get a chance to wirelessly charge a Tesla Model 3. There’s been a lot of progress in the past two years. Is wireless EV charging almost here? Let’s take a look.
Wireless charging isn’t anything new. Inductive charging has been around for a long time and you may even use it every day, like an electric toothbrush or your mobile phone. However, charging an EV is a completely different ballgame. We’re talking about magnetic resonance charging, which is what the company Witricity in Watertown, MA is bringing to EVs. Here’s how Alex Gruzen, Witricity’s CEO, described it to me in 2020.
“So our technology is called magnetic resonance wireless power transfer, often just called magnetic resonance, and it builds upon a history of induction charging but it shifts it in a pretty radical new way, which is it makes the two coils each very efficient resonators that operate tuned to a particular frequency. And by making them efficient resonators, it’s like pushing my kid on a swing where little taps of energy could result in the swing really moving. In this case, because the source, the pad on the ground and the receiver that’s built into the car are both tuned to the same frequency, around 85 kilohertz. And each of them is a very efficient harmonic resonator. The energy moves efficiently between the two. Traditional induction, you have to have sort of perfectly matched coils. They have to be very close to each other and they have to be in perfect alignment. But with magnetic resonance, you don’t need that. You can have offsets, you can have different heights and you can have different sizes just as long as you keep them sort of operating in the same sort of operating frequency. That was really the breakthrough.” -Alex Gruzen
Breakthroughs are all well and good, but as many people point out in my comments, will we ever get to see it in the real world? That’s precisely why I decided to revisit them to see how things are progressing. One of the big obstacles in getting wireless EV charging to market was ratifying a standard across the industry. Witricity worked with SAE International on the J2954 wireless charging standard for about a decade, which was released in October of 2020.1 That unlocks a lot of what’s happening now.
When I originally talked to WiTricity in 2020 they were very focused on supplying the technology, but things have shifted a bit since then. Alex filled me in on where things stand today…
“For the first several years of the business, we were in a technology transfer and licensing model. But the objective has always been that as the market happened and vehicles coming to market with our technology embedded, there would become an opportunity to sell chargers and charging equipment. That’s the transition. We’re going from enablement and the first launches to actually deploying our own product into the field.” -Alex Gruzen
Witricity is going to be bringing its own line of products to market. As proof of concept, they’ve been retrofitting existing EVs for wireless charging, so it shouldn’t be a surprise that they targeted a Tesla Model 3. But while I was there I stumbled upon something I wasn’t expecting … they were actively working on two Ford Mustang Mach E’s. After talking to some of their engineers and team it’s pretty clear that it’s challenging to design a retrofit for a car that wasn’t originally designed with wireless charging in mind.
Some of the considerations you have to take into account are space. You have to be able to squirrel away the charging pad and equipment on the underside of the car. You also have to wire into the electrical system, override safety protocols of the charging system while also designing your own safety protocols to replace or supplement those. For instance on the retrofitted Tesla Model 3, while you’re wirelessly charging the car, they implemented a software override that disables the external charging door from being opened because it’s technically live even though you aren’t physically plugged in. If you manually pry that door open, the wireless charging system automatically shuts down. What they’ve demonstrated on the Model 3 is extremely safe, but this does show the level of care that has to be taken when designing a retrofit like this.
“It’s actually quite a bit of work if you’re doing it sort of independently as an aftermarket thing. For us, we are developing aftermarket kits. The primary focus is going to be commercial fleets and we’ll make it available to some enthusiasts in the space as well. But the core of our business has always been about enabling the auto makers. We’re in production now in South Korea and in China with auto brands for factory installed solutions.” -Alex Gruzen
For the “designed for wireless charging from the ground up” partnerships, they’ve partnered with Hyundai on the Genesis GV60, which is available in South Korea. The cars’ built in screens and cameras are used to help guide the driver to the proper charging position. In China, FAW is bringing wireless charging to its HongQi E-HS9 (a product name that rolls right off the tongue). What’s really cool about FAW’s rollout is that they’ve paired charging with autonomy, so the car parks and charges itself.2 There are more partnerships in the works, so I expect we’ll be seeing a trickle of news coming out of Witricity in the months and years ahead.
That’s all well and good, but what’s it like to use? On that point I got a chance to try it out for myself. Since the Tesla Model 3 is a retrofit, they had to add a secondary screen to give the driver real time feedback. I know some people will see this as a downside, but I actually don’t. Just recently I added an extra screen behind my steering wheel on my Model 3 to get Apple CarPlay into my car. Not to go off on a tangent, but I really like the screen. It’s nice having a speedometer there when I’m not using CarPlay and the addition of CarPlay is a game changer for me. Witricity is doing something similar. When you’re not near the charging pad, the screen displays a speedometer. Now keep in mind that everything you’re seeing is a work in progress and not a final UI, since right now they’re focused on nailing the functionality. (No offense to engineers– I spent my entire career working closely with software engineers and they can do some amazing things, but they aren’t always the best at UI design.) As you get closer to the charging pad, the system automatically switches over to a charging view on the screen.
I’ll be honest with you, I was a little nervous about nailing this on the first try, but I did it. As Alex explained with how magnetic resonance charging works, you don’t have to be precisely aligned to get an optimal charge. There’s wiggle room and a window you’re aiming for. What really surprised me was the level of accuracy they can pinpoint for how the pads are aligned … right down to the millimeter. Obviously, they won’t be showing millimeter readouts on the final product, that’s just for development, but you can see from my trial run that there’s a fair amount of wiggle room on the alignement.
For charging speeds it’s on par with what you get at home or on a lot of destination chargers today. It’s an 11kW charger, which can add about 35 miles an hour onto the car. It’s on par with what I have in my house with my plug in Tesla wall connector. And there’s an important point to bring up around charging speed and efficiency. That 11kW isn’t the limit of magnetic resonance charging, it’s the limit of the consumer model they’re building and releasing.
“We have under development higher power solutions. For last mile vans, for middle mile trucks, for shuttle buses and for transit buses. So you can do anywhere from say 50 to 75 kilowatts all the way up to hundreds of kilowatts for those vehicles with the same sort of architecture that we’re deploying down to 11 kilowatts for a passenger car.” -Alex Gruzen
It’s all about designing the system for the specific use case. If you’re targeting a use case for home or business destination charging, 11kW is a great target, but they can scale this way up based on the use case.
As for efficiency, this one can be hard to wrap your head around because all of us may equate our experience with a Qi charger and your phone, but this is very different. Qi charging is usually about 80% efficient at best and requires very specific contact and alignment. Magnetic resonance is about 99% efficient over the air gap, so it’s virtually identical to plugging in. When you factor in the full system (circuit to inverter to battery) it’s about 92% efficient, which is right around where wired charging is.
That’s not the part that gets me so excited about wireless EV charging though. There’s two use cases that get unlocked: one of which I already touched on … and that’s autonomy. FAW’s autonomous parking and charging car is where this is all heading in the future. If you remember a number of years ago, Tesla was experimenting with this snake-like robotic charging arm that could automatically plug into your car. That’s a fairly complicated solution with lots of moving parts that can break down and need maintenance. A wireless charging system sidesteps those problems completely. The other thing that gets unlocked is vehicle to grid (V2G). We’re starting to see more EVs coming to market that support bidirectional charging, so you can power your home from something like a Ford Lightning truck. The one thing that’s always bothered me about V2G is that you have to remember to plug in to take advantage of some of V2G’s benefits beyond just power in a blackout. With bidirectional wireless charging, not only do you never have to worry about forgetting to charge your car for the next day’s driving, but the largest battery in your home is ready to participate in peak shaving programs or blackouts … automatically.
“Most people, if the car’s batteries are fully charged, they don’t plug in. And that’s when it’s most useful for V2G and if it’s not plugged in, it’s like useless. With wireless, if it’s parked it’s available. I think that wireless V2G really is kind of going to be an amplifier for V2G in general because all of those parked vehicles suddenly become available.” -Alex Gruzen:
What about the cost of the system? Alex broke this down for me too.
“Obviously we’re at the early days. I can tell you that the part that goes on the car, we call it a vehicle assembly or a wireless power receiver, cost about the same today as an onboard charger, which you would have on there. So 5, 6, 700 bucks to an auto maker to install on the car. We have a roadmap of product that gets that down to a few hundred bucks. Within a few years, adding wireless charging to your car will be kind of the same as adding 20 inch wheels or a nav system or a moonroof … the charger for the home, it’s a couple grand and I think that’s going to be the market price. It’ll be roughly about a thousand bucks more than a nice premium plug-in charger.” -Alex Gruzen
The last time I talked about Witiricty, I got a lot of questions about the safety of the system. For instance, what happens if you have a cat that likes to crawl under your car? This is another one of those things that can be a little hard to wrap your head around, but the system operates at a low frequency which is very safe.
“The most popular home addition these days is an induction cooktop. Well, induction cooktop operates under a finite set of radio laws, totally safe, and the same apply for us. You know how an induction cooktop can heat up a pan. Well, if a soda can or a coin or something were to go on the pad while it’s charging, it would heat up. Well, if we could put energy into it, it also means we can detect it. We have a series of sensors we’ve designed that notice if any metallic object is anywhere near the pad, it turns off. Same for your cat. If you’re to reach under and go near the pad, the system would turn off. Does that mean it’s not safe? No, it actually is safe. If anything goes near it, we’re going to turn off, give you a notification and you go about your business.” -Alex Gruzen
So when will you be able to get your hands on wireless charging for your EV? It’s already on the market in certain regions, but Witiricty is trying to ramp that up with new partnerships. Just this past June, Siemens invested $25 million into Witricity to help accelerate the rollout and they see this as a multi billion dollar market. But given how slowly the automotive industry typically moves, it may be several more years before we see this trickle out in a meaningful way. At least we should start seeing after market options for specific models hitting the market at some point down the road too. I’m pretty excited for the future of this tech and can’t wait to get it.