Wireless EV charging: Everything you need to know about going cable-free

Far and away, the biggest headache of EV ownership is charging. Public chargers are often unreliable, slow, or simply not available where you need them. EV charging at home is much easier, but dragging a heavy, dirty cable across your garage or driveway is no fun. That's doubly true if it's cold out and that cable is stiff or covered in snow.

Wouldn't it be nice if you could just park your EV and walk away, letting the thing charge itself wirelessly? That might sound like science fiction, or perhaps a recipe for making all the wildlife in your neighborhood glow in the dark, but it's a reality and a safe one at that. Wireless chargers have the potential to be fast, easy, and safe, too. 

But with minimal adoption and developing standards, we're still at least a few years away from mainstreaming this utopian dream of perpetually full electric vehicle batteries. Buckle up because we're going to delve into all the details.

Wireless charging is any technology that allows you to add charge to your EV without having to physically plug it in. We'll get into the nuances of how that works in just a minute, but first, let's talk about the two high-level types of wireless charging. They boil down to one key difference: whether or not your car is moving.

The first is called dynamic wireless charging, and as you can probably guess by the name, that entails any technology that charges your car while it's in motion. The technology is proven and plenty of researchers worldwide are trying to make it a practical reality. However, since no near-term deployments are likely, we won't spend more time discussing this here. 

The second type is static wireless charging, which is a term for the kind of charging that works when your car is parked. This technology is already a reality in limited applications, particularly when it comes to industrial and fleet electric vehicles, and it's close to becoming practical for at-home use, too.

To understand how wireless EV charging works, it helps to understand how EV charging works in general. To get that, we need to understand how EV batteries work. While the battery packs that make up the floor of your average electric car are substantially more advanced than those in your smartphone or smartwatch, conceptually, they work in the same way.

A battery is two conductive surfaces separated by a non-conductive substance called an electrolyte. One of those surfaces is positively charged. This surface, the cathode, gains electrons through the battery's typical chemical reaction. The other surface is negatively charged. This anode supplies the electrons that makes the reaction work. 

It's the electrolyte in between that makes the process work, chemically joining the anode and cathode and allowing ions to flow. Electrons catch a ride on those ions, and the flow of electrons moves your car. 

Now, when you plug in your EV to a charger the (soon-to-be) old-fashioned way, you're effectively pushing those ions back from whence they came, ions loaded up and sent zipping back across the electrolyte to provide power for your next drive.

Wireless charging does the same thing but in a more nuanced way. The more formal term is inductive charging, which allows an electrical circuit to recharge a battery without physical contact. 

Believe it or not, this technology is old—really old. It's discussed in a patent dating back to 1894 related to powering electric vehicles. (The model used in the patent is a self-propelled railway car, but the concept could have just as easily been applied to a car.)

Sadly, that technology didn't catch on then, but it is commonplace in other industries. Inductive charging has been used to recharge things like wireless toothbrushes and medical devices for decades. Many of the latest smartphones include a form of inductive charging, too. 

Solutions like this rely on two matching induction coils, which are electrical components that create an electromagnetic field when applied with current. The first coil is embedded within a charging pad, which provides the current. The second induction coil is integrated into the device being charged. 

When the receiving coil is placed close to the field created by the first coil, a so-called electromotive force is generated. This induces a voltage in the receiving current, moving the electrons to re-stock those ions in the battery.

To wirelessly charge an EV, the charging pad sits on the ground beneath the vehicle, and the car itself has a receiving coil built into the bottom of it. This way, they're positioned close to each other to pass the charge along. 

The farther the receiving pad is from the charging pad, the less efficient that charging rate is. That's why you'll typically lay your phone or smart watch right on the charging pad. That brings us to our next question.

Transmitting power through thin air seems like it should be vastly inefficient when compared to wired charging. And, to be clear, there is a loss of efficiency when you're talking about wireless charging, but it's hard to pin a specific number onboard. 

General wireless charging efficiency figures for devices like smartphones tend to be around 70 to 80 percent, meaning a significant 20 to 30 percent loss. When it comes to charging EVs, the numbers aren't so simple. 

Amy Barzdukas is CMO at WiTricity, one of the leading providers of wireless charging solutions for electric vehicles. She says that the company's wireless chargers have an overall efficiency of 88 to 93 percent, with the wireless transmission itself being between 96 to 99 percent efficient. "Because we use magnetic resonance with specially designed low-loss resonators to transfer power, the loss is very small," Barzdukas said in an overview of overall charging efficiency.

However, Barzdukas points out that your average, wall-mounted, wired charger typically delivers an overall efficiency in the 80 to 90 percent range. There are many variables depending on everything from cable type to manufacturer, but the important point is that wired charging is not necessarily much more efficient. 

It's also not necessarily faster to charge your EV using a cable. WiTricity offers speeds of up to 11 kW from the company's Halo wireless charger, which is close to the 11.5 kW output you'll get from most Level 2 chargers that support 48A as maximum output. 

That might mean an eight-hour wired charge would take an extra 20 minutes wirelessly, which is hardly a deal breaker if your car is sitting there overnight anyway.

The biggest advantage of wireless charging is simplicity. You park your car and walk away. Eventually, this could become so automatic that you forget you're even charging your car in the first place.

Because of this, you're more likely to partially charge your car in small doses, keeping your battery within the 20 to 80 percent charging range where it's most happy. Fewer, larger charging cycles do more battery damage than more frequent, smaller ones. 

Finally, wireless charging could also simplify public charger installation. While embedding chargers into parking spaces and the like could be expensive, maintenance could be easier than keeping cables and their connectors functional and operational in all weather conditions.

The biggest concern with wireless charging is availability, which we'll get into in just a minute. Beyond that, a significant problem is cost. Some of the most popular residential EV chargers are available for under $400. While pricing for the company's home EV charger isn't available yet, WiTricity's Barzdukas told us it will "come at a premium to existing L2 chargers today." 

Expect to pay thousands rather than hundreds, plus they'll require modification of your car to install.  

Another disadvantage is heat. Wireless charging has the potential to generate additional unwanted heat during charging compared to wired charging. However, this is mostly only a concern in consumer electronics like smartphones. Modern EVs have advanced battery cooling systems that should mitigate this issue. 

Today, the answer is basically none. Plugless Power promised a charging solution for the Tesla Model S in 2016, but it has yet to deliver. BMW offered a wireless charging option for its 530e plug-in hybrid in 2017, but that was just a limited pilot program. Meanwhile, WiTricity has demonstrated its Halo working in numerous mainstream electric vehicles, like the Genesis GV60 and the Ford Mustang Mach-E. Still, that system is unavailable for consumer purchase. 

The news should get a little cheerier soon. When Ram introduced its 1500 Revolution concept electric truck at CES in 2023, it showed off a novel wireless charging solution. Instead of installing a charging pad on the floor of your garage or driveway, Ram's pad was motorized. The idea is that you park your truck and the charging pad scurries across the floor to start the charge.

That was a bit of a flight of fancy, but it shows that a major manufacturer saw wireless charging as a priority for the future, at least. WiTricity's Barzdukas told us it's coming soon, but not necessarily with trucks: "We think that some of these more vocal early adopters will lead to rapid growth, likely beginning with luxury brands, which is where new automotive technologies tend to be introduced first."

In the nearer term, WiTricity's consumer-grade wireless chargers will start in the low-speed vehicle, or LSV market. LSVs are a class of small vehicles that are closer to a golf cart than G-Class. They're popular in larger, age-restricted communities like The Villages in Florida. LSV's are largely electric, and WiTricity's solution allows owners to charge them wirelessly at home. This solution is slated to hit the market in the summer of 2024.

At this point, the answer is also no, but that may change soon. In early 2023, Tesla acquired Wiferion, a European company specializing in wireless charging technology. Since that company had licensed WiTricity's technology, there was speculation that future Teslas might include the same wireless charging technology standard.

The new Cybertruck is also said to have additional connectors that might be used for a wireless charging add-on, so there's hope a solution might be coming soon.

Since there really aren't any mass-produced cars available with wireless charging installed, it makes sense that there's no public wireless charging, either. With no clients to support, there's simply no infrastructure.

But it's coming. "We're past hoping for it, we expect it," WiTricity's Barzdukas told us. "By being able to install chargers curbside where people actually go, drivers will be able to grab “power snacks,” which is what we call short charging events in convenient curbside parking spots."

With any luck, once a few manufacturers start offering wireless charging in their cars, the market will quickly follow. Maybe then we can finally stop dragging dirty cables around every time we park and can instead just go about our business.