How wireless charging will power your smartphone through the air

Here's how your smartphone will recharge its battery through the airwaves — without you ever needing to worry about a cable, jack or battery pack

Originally posted by Stewart Wolpin in GearBrain

Imagine never having to plug in your smartphone to recharge it. Imagine a world where you're sitting in a restaurant, wandering through an airport, on a plane or at your desk — and your smartphone just automatically recharges. No more AC jack, USB charger and cable, no more battery packs.

There is wireless power charging right now. Qi (pronounced "chee") is now finally deployed by all the major smartphone brands. But Qi is a "near field" wireless power: the wired charger is just replaced by a pad.

The next generation of wireless power works like radio and Wi-Fi, transmitting power as if your device is powered by air. Up to 5 watts – aka "power snacking" – enough to power your smartphone or other small battery-powered devices, beamed from an AC-connected transmitter to around 10 meters or 30 feet away. The power goes into a chip-based receiver imbedded, or attached, to your battery-powered device.

Wireless power transmitters can be standalone devices or built into existing products that are already plugged into AC. An overhead light can be a transmitter, so too a smart LED lightbulb, a TV or desktop PC bezel and a a smart speaker. The first receivers will likely be a smartphone case, or a dongle. Eventually, they'll be built into devices.

Sounds like utopia, yes? Perhaps, except that wireless power transmission — what we are going to start calling "air power" is not being developed the way Wi-Fi and Bluetooth were — by, or under the auspices of, independent and objective standards groups such as the IEEE. There are at least four companies creating proprietary — and more importantly incompatible — wireless power transmission ecosystems. Some systems operate via radio frequency (RF) similar to Wi-Fi. Others use infrared (IR) like your TV remote, or even ultrasound, each with their own pros and cons. For instance, IR and ultrasound wireless power transmission operate via line-of-sight, which means they can't charge devices tucked in pockets or bags, around corners or behind walls. That's inconvenient.


Radical Shifts

The underlying principles of air power date back to Nikola Tesla and to Michael Faraday and James Clerk Maxwell in the mid-18th century. Today, this new attention to air power is likely to shift how you interact with all the devices in your life.

On a day-to-day basis, your attitude toward charging your toys will happily change from active to passive. Sure, charging a smartphone from near dead via air power will take two-to-three times longer than plugging into a wall outlet. However, an air-powered smartphone is theoretically charging all the time, which means it's unlikely your smartphone would ever run out of juice: you'll never worry about your smartphone's battery level again.

Ditto for the next generation of air-powered AV remote controls, Bluetooth headphones, speakers and keyboards, smart watches and fitness bands, smart locks, Wi-Fi security cameras, door/window sensors – and all low-power battery-powered gear. They'll just always have juice. It's also not hard to imagine a future in which some AC-powered devices such as a toaster or printers includes a power cable as a last resort.

Is It Safe?

Just how safe are these air power schemes? First, check out this photo of Tesla calmly sitting a room filled with all manner of stray electrical charges. See? Electricity in the air didn't seem to cause Tesla a problem. Plus, RF-based air power systems essentially operate the same as Wi-Fi does.

While its hard to absolutely guarantee that there will be no ill-effects , note that all air power vendors in the U.S. must receive FCC or FDA approvals for RF and IR power, respectively, certifications that also include safety qualifications. According to Yuval Borger, chief marketing officer of Wi-Charge: "Governments worldwide issue comprehensive regulations to assure public safety. In general, there is good agreement among national regulators worldwide on permissible exposure limits."Likely air power will be deemed safe, even when delivered at longer distances and at higher power, with enough juice to charge devices such as laptops, robot vacuum cleaners, media streamers, air purifiers and, maybe, even the most power-hungry mobile device, drones. "The distances that can be achieved, theoretically, are really unlimited," notes Sanjay Gupta, president of the AirFuel Alliance, a non-profit organization proposing interoperability control and command protocols for wireless power systems, "…and we're limited to 5 watts but we're getting a lot more in the lab. The constraining factor is safety and the regulatory environment."


The Players

Four companies – well, maybe three – seem poised to launch the air power revolution: Energous with its RF-based WattUp system; the RF-based Ossia and its Cota (Charging Over The Air) system; the IR-based Wi-Charge; and, the ultrasound-based uBeam, which may or may not be the air power version of Theronos. Each of these companies license their technologies to device makers and, for those that don't fabricate their own silicon, chip-makers.

Trying to herd all the wireless charging cats is the aforementioned AirFuel Alliance. While the Alliance boasts more than 70 members, only one – Energous – is working on an actual air power system. Ossia, Wi-Charge and uBeam are NOT AirFuel Alliance members, probably because each is trying its establish its own de facto air power standard, which would be a hugely profitable prize.

So which air power contender is likely to emerge?


Energous is a public company (NASDAQ: WATT), well-funded, has the necessary government regulatory approvals in the U.S. and worldwide, and boasts a partnership with a top 10 consumer electronics company. Energous CEO Steve Rizzone does admit, however, there's no guarantee that its technology will actually appear in any of its own products.

Energous is readying a three-pronged RF-based wireless power ecosystem called WattUp, all from the same tiny (3mm) and inexpensive (less than $10) chip set: contact, "near-field" – which can transmit up to a couple of feet away, and another at a distance up to 15 feet away. Each will roll out in timed phases, with the final longer distance "air power" transmission technology, due in late 2019/early 2020. According to Rizzone, "a number of companies will begin ordering manufacturing quantity chip sets toward the end of th[is] year." While Energous seems the best positioned among the air power providers, even Rizzone readily admits "we're not going to own the market."


Ossia (pronounced "oh-SIGH-ae") is developing several RF air power schemes for different applications under the Cota brand. Its 2.4 GHz-based systems, for instance, are designed to deliver wireless power to largely stationary products such as smart home devices, and at 5.8 GHz for smartphone, handheld and IoT gear. One of Ossia's most fascinating implementations are its Forever Batteries. These are air power receivers in the form and function of standard AA and AAA batteries, which never die as long as they receive power from an Ossia air power transmitter.

But Ossia is working with a variety of partners. According to the company, "Cota technology is currently ready to be licensed by our partners. We are in different stages of development with multiple players. Depending on the implementation, Ossia expects partner companies to be shipping Cota-enabled products by the end of 2018 or early 2019." However, this timeline is likely dependent on regulatory certification; the company notes it "is currently working toward FCC approval and expects it to come in the coming months."



Using IR, this Israeli company is able to transmit up to 3 watts of power from a ceiling or shelf-based transmitter to low-power battery-powered Wi-Charge compatible/enabled devices up to 15 feet away and within a 90 degrees radius. While the company has demoed Wi-Charge's system by powering of an electric train around a plastic track, the company's CMO, Yuval Boger, believes charging smart home devices such as smart locks are the system's most effective application.

The first Wi-Charge-enabled products are due early next year, which will beat everyone into the air power market, and are likely to include ceiling-mounted Wi-Charge transmitter light fixtures, Wi-Charge-enabled Qi wireless charging pads, Wi-Charge shelf transmitters, Wi-Charge dongles and smartphone cases. The company claims to have been contacted by 2,500 potential customers, and is working to install Wi-Charge transmitters in restaurants, coffee shops and other public facilities.

More powerful transmitters sending more power over a longer range are already on the roadmap. There's only one giant fly in this ointment: Wi-Charge's IR technology operates via line-of-sight, which means the system won't charge devices in your pocket, in a bag or around corners. While Wi-Charge might be first-to-market, IR charging might eventually be a stumbling block for widespread consumer adoption, regardless of its other advantages. Line-of-sight demands an extra level of attention to transmitter and device location that consumers may decide just isn't convenient enough compared to less restrictive RF air power solutions.


There have been numerous charges that uBeam's wireless charging technology is a sham. The company did conduct a couple of limited live demos last year and earlier this year, but these raised anew questions about the veracity of the company's claims and the practicality of its technology. For one thing, it seems that ultrasound is absorbed by air, which means there could be extreme power loss beyond a few meters. And, like IR, ultrasound is hampered by line-of-sight issues. There's been no public word from uBeam since a blog post in May on its otherwise detail-impaired web site, a blog that makes several inaccurate claims about the company's technology's competitive uniqueness. But even if uBeam tech worked as advertised, which most experts don't believe, it doesn't look as if it will make any kind of impact in the near-term.


Air Power's Future?

Given the recent half-decade battle between PowerMat and Qi — which stalled widespread adoption of a universal resonant induction charging solution — it's clear that an air power format war helps no one.

"Growing the pie is in everyone's interest," says the AirFuel Alliance's Gupta, "rather than fragmentation and everyone playing in their own sandbox. If some company decides that it is in their interest to go do something, often they're on an island. A unified standard is absolutely the more desirable option."

Since some sort of incompatible competition is likely, we're facing one of three potential air power scenarios:

  1. One of the four challengers somehow establishes a dominant market position, winning the air power format war before it even has a chance to get started.
  2. Two or more contenders get together and combine technology and marketing forces. But, the only pairing that makes sense is Energous and Ossia since they are the only two RF air power providers. This pairing is unlikely, however. Their transmission approaches are radically different, and Ossia isn't an AirFuel Alliance member. When I asked why Ossia hadn't joined the Alliance, all I got was: "As Ossia doesn't have a relationship with AirFuel Alliance, they unfortunately cannot provide additional commentary at this time surrounding the topic."
  3. A format war that drags out for five or six years until either Apple and/or Google – since smartphones are the most important and voluminous product screaming for an air-powered solution – buy or adopt one or the other, or if an independent industry standards organization provides an imprimatur, or both beat each other up leaving only one standing.

Whatever happens, the air power revolution will soon begin. Who ends up winning and when we'll be able to dump our chargers and stop worrying about our phone's battery level is anyone's guess. But this air-powered future is inevitable.