Why wireless charging is important for electric cars

If you’ve severed the cord for your smartphone with a bedside charging pad and one in the car – and, if you’re lucky – wireless CarPlay or Android Auto – you’re probably getting the idea of ​​what a groundbreaking wireless device inductive charging could be be for electric cars.

Instead of trying to juggle a toddler or a bag of groceries while carrying a clunky cord and charging plug morning and night, it could just be a matter of parking, getting on with life, and returning to a charged vehicle.

And once you’ve experienced it, there’s probably no going back. When was the last time you thought about plugging an Ethernet cable — or a phone line — into your laptop?

How does wireless charging of electric vehicles work?

Wireless charging uses the principle of electromagnetic induction to transmit electrical energy through air as a magnetic field. You might also hear inductive charging – or, redundantly, wireless inductive charging.

Volvo tests inductive charging with C30 Electric

In short, electricity induces a current on a coil of copper wire and emits it at a specific frequency – a frequency not far removed from FM radio frequencies for the most likely applications. This creates an oscillating magnetic field, which is then captured by another copper coil.

With fine-tuning of the signal as a function of distance and the help of capacitors – and some nuclear physics ideas like the idea of ​​resonant frequencies – wireless charging for electric vehicles can become viable without wasting too much energy in the process.


Technically, the system requires two sets of hardware: a transmitter pad for the driveway or garage floor that plugs into a dedicated circuit, just like a wall charger, and a receiver pad that installs on the underside of the vehicle.

2018 BMW 530e iPerformance Wireless Charging

2018 BMW 530e iPerformance Wireless Charging

2018 BMW 530e iPerformance Wireless Charging

2018 BMW 530e iPerformance Wireless Charging

2018 BMW 530e iPerformance Wireless Charging

2018 BMW 530e iPerformance Wireless Charging

Systems from WiTricity, which has emerged as a technology leader, and others adhere to the J2954 standard, which was developed to enable reliably usable wireless charging at a distance of between 10 and 25 cm (3.9 and 9.8 inches). , which takes into account the ground clearance of almost every production vehicle, from sports cars to off-road SUVs. And at 11kW of power, it gives the typical EV back about 35 miles of range per hour parked.

With an alignment method built in as standard, a low-power beacon signal from the pad helps either indicate to the driver where the vehicle should be parked or automates the process. A Wi-Fi handshake completes what will essentially be a touchless version of Plug and Charge – essentially Park and Charge. Voila.

Since about 85% of charging is done at home, this is designed as a daily charging method, not as a special occasion technology for road trips. “Ultimately the car will feel like they have an infinite range car,” said Alex Gruzen, CEO of WiTricity. “They drive it, they park it, they never have to do anything.”

How efficient is wireless car charging?

The efficiency of Qi wireless charging in your smartphone is 80% at best, but most likely less than 70%, which is why your phone gets so warm when you remove it from such a charger. This system was designed to be thin and cheap, but with such a higher level of energy, a car charging system this way cannot be wasteful and has been specifically designed for efficiency.

Nissan wireless charging system

Nissan wireless charging system

Efficiency has improved since a few automakers last explored the technology for factory installations — like Nissan did for the Leaf more than a decade ago (above). From coil to coil, WiTricity’s technology captures 99% of the energy transported across the air gap. Most other stages are the same – and no lossy isolation transformer is required, saving energy. From the switch box to the vehicle, the efficiency of a wireless system is typically 90% to 92%, right where most plug-in chargers are.

why is it better

From a market perspective, wireless charging technology could make everyday EVs much more livable – especially for those who find daily charging cables and connectors a nuisance.

While those cables and connectors need to be replaced every few years, wireless charging hardware doesn’t show these wear points. Even snow and ice don’t get in the way.

Wireless inductive charging system from Mercedes-Benz

Wireless inductive charging system from Mercedes-Benz

As we achieve higher levels of EV adoption and wireless charging becomes more widely used for convenience, this will potentially reduce the need for DC fast charging, which puts more strain on the power grid.

What are the disadvantages?

The cost is the big one. The option price for wireless charging is likely to be in the thousands. Given the need for two large sets of hardware components, it will always cost more than a wall or postal charger.

Since the charging pad is much more difficult to move than a charging port, the inflexibility of wireless charging could be a problem for some households used to changing parking plans late into the night.

Interoperability between mixed and matched wireless charging components shouldn’t be the issue; That was the point of waiting for the industry to agree on a standard, and it’s here.

Which electric vehicles offer wireless charging?

Currently none in the US, but that is set to change soon.

2023 Genesis GV60

2023 Genesis GV60

The rollout has started globally and it’s all very new. The Genesis GV60 offers the world’s first factory integration of wireless charging and is included in South Korean versions for the domestic market as part of a pilot program. Hyundai incorporated the technology into the development of its E-GMP platform for dedicated electric vehicles, so expect to see the technology in more models and markets soon.

In China, the technology has been newly adopted in Hongqi electric vehicles by FAW and IM Motors, a joint venture between Chinese company SAIC Motor and e-commerce giant Alibaba. It is also included in the Alibaba-supported Zhiji L7.

Aftermarket wireless charging solutions have been around for years – most notably from Plugless Power, which offered a system for the Tesla Model S. A Tesla Model 3 system from WiTricity is also in the works.

BMW 5 Series Plug-in Hybrid Wireless Charging System

BMW 5 Series Plug-in Hybrid Wireless Charging System

BMW has been testing wireless charging in the US in its 5 Series plug-in hybrid, but the testing hasn’t expanded beyond a small pilot program.

Other labs and startups are currently working on high-power wireless charging at rates comparable to DC fast charging, but it could be a decade before this becomes a viable option.

Why hasn’t wireless charging caught on yet?

Simply put, the technology is not yet mature. But it’s been in the works for a long time.

Wireless charging was originally proposed and demonstrated by Nikola Tesla more than a hundred years ago, but it has been in an experimental application phase for decades. A number of advances over the last 15 years have accelerated the advancement of technology to a point where it is reliable, efficient and easy to package.

While Qi wireless charging for smartphones may mark the first time this technology has gone mainstream, it was first tested and used in vehicles decades ago. But a series of consolidations in recent years has helped make it more commercially viable. Halo and WiTricity both launched in 2010, taking wireless vehicle charging efforts from university labs to fledgling companies. Qualcomm bought HaloIPT in 2011, then acquired and merged US-based WiTricity, which had been working on its own slightly different solution, with Qualcomm Halo in 2019.

Wireless charging in the car park - WiTricity

Wireless charging in the car park – WiTricity

After that, “WiTricity immediately went to work consolidating the architecture… getting the best of both sides to present the SAE with a common architecture that we thought was the answer,” Gruzen recalls.

This was critical to achieving the SAE J2954 standard ratified in October 2020 – essentially a signal that the technology can be brought to market.

The future

Global auto and vehicle supplier Siemens invested US$25 million in WiTricity in June 2022 and this partnership will result in solutions for the home, parking lot, workplace or fleet.

Siemens expects the wireless charging market to reach $2 billion by 2028 in Europe and North America alone.

ORNL demonstration of wireless charging with a UPS hybrid truck

ORNL demonstration of wireless charging with a UPS hybrid truck

Although home solutions – and the current SAE standard – go up to 11kW, we will see higher powered versions of this system for fleets. That could largely come from a different group of companies, including HEVO and Momentum Wireless, among others. Separately, there’s another group of companies working on wireless dynamic charging — a relative pipe dream for now, that charges vehicles using some of the same principles as how the vehicle is driven.

The aftermarket could also grow. Plugless Power, which has previously sold aftermarket systems for the Tesla Model S, Nissan Leaf and others, will also be introducing new-generation systems this year at a target price of about $3,500, with a system that achieves pad alignment via an Apple CarPlay interface.

Evatran Plugless Wireless Charger for Tesla Model S

Evatran Plugless Wireless Charger for Tesla Model S

WiTricity points to the company’s own-commissioned surveys, which show a growing interest in a technology they’ve likely never personally experienced in cars. It found that just because of the concept of ‘EV considerations’, those who hadn’t yet committed to the idea of ​​buying an electric car increased their purchase intent with the availability of wireless charging from 35% to 59%. A recent survey for the company found many non-EV owners want it as an option in a future EV.

“For ten years, it’s been a conversation with a group of engineers in a room,” Gruzen said. “Now we have a real product on the market.”

And if the price goes down and all early adopters have bought EVs, it could help attract many more Americans to EV ownership.

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