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This Transmitter Will Charge Your Gadgets from Across the Room

·Tech Critic

Usually, when tech companies speak rhapsodically about “wireless power,” what they mean is, “you can recharge your phone by setting it down on a mat.”

Well, OK. It’s slightly easier to put your phone down on a mat than to plug in its power cord.


But that’s not really wireless charging. It’s not charging through the air, like a WiFi signal. You can’t keep using the phone while it’s charging.

No wonder the wireless-mat thing hasn’t really caught on.

The next wave, though, will probably get your attention.

Meet RF charging

At labs all over the world, engineers are getting true, distance charging technologies ready. That’s just what it sounds like: Thanks to a special transmitter, your phone, tablet, smartwatch, hearing aid, and fitness band will be charging all the time, as you go about your day. You won’t take them off. You won’t plug them in. And you’ll never worry about making it through the day on a charge.

A product’s battery life, in fact, will become irrelevant.

So how close are we to this fantasy? Very, according to Steve Rizzone. He’s the CEO of a 50-person company called Energous, whose distance-charging technology (with the unfortunate name WattUp) is, he says, by far the closest to being ready for market. He came by Yahoo’s New York office to give me a demonstration.


He handed me an Android phone in a special case. About six feet away, he plugged in the transmitter: a shiny black plastic box that looked something like an oversized WiFi router.


Using a tablet as a remote control, he could turn on the transmitter; at that point, the phone’s “charging” indicator came on, right there in my hand—not plugged into anything. The phone was, in fact, getting an electric charge through the air.

Rizzone also had an electric votive candle on hand; its low power requirements were meant to represent a smartwatch or fitness band. Once again, he could tap a software switch on his tablet to make the candle light up, indicating that it was getting power.

Through. The. Air.


The Frequently Asked Questions

Once I saw all of this working, I was, of course, bursting with questions; you’d probably have most of the same ones. Here’s what he told me.

Q: Is this going to fry my guts?

A: No. The transmitter is sending out an RF (radio-frequency) signal—the same kind of signal transmitted by WiFi or cellphones. Not only is the signal even weaker than your phone’s, but it’s reflective; it bounces off skin instead of going through it.

(To underscore the inability of these waves to penetrate the skin, Rizzone told me a story about a pacemaker manufacturer who contacted him. The manufacturer was all excited about WattUp. Imagine if we could recharge people’s pacemakers without requiring surgery to change the battery!
But there ya go. That won’t happen, because RF waves bounce off the body.)

Q: How does it work?

A: The transmitter contains an array of small RF antennas. They send out “23 dBm across a 120-degree directional span, creating a 3D pocket of energy using the 5.8GHz unlicensed ISM RF spectrum.” 

Translated from Engineerspeak, that means a focused pocket of power will be collected by any receiver-equipped gadget that happens to be within a 120-degree arc from the transmitter.

The hard part is not wireless charging, Rizonne says; it’s focusing the array of antennas on each gadget. In WattUp’s implementation, your gadget’s Bluetooth circuitry provides a focusing target for the RF beams that converge from floor, ceiling, wall, and furniture reflections.

Q: Can it charge more than one thing at once?

A: Yes—up to 12 devices simultaneously.

Q: What’s the range?

A: The strength of the charging drops off rapidly with distance; at the moment, 15 feet is the maximum range of the transmitter.

At 5 feet, your gadget (actually, four of them at once) can receive a maximum of 4 watts. At 10 feet, it gets 2 watts; at 15 feet, 1 watt.

Q: Is the transmitter sucking power all the time?

A: No. When there aren’t any WattUp receivers in range, Rizzone says that the transmitter goes to sleep.

Q: What’s the deal with the tablet he’s using?

A: The WattUp system is designed to be configurable. You can specify which gadgets get priority when they’re in range, using either the phone/tablet app or a Web portal. You can also set up a schedule, so that cellphones get priority when you’re home, but your remote controls and wireless mouse get charged while you’re away.

Q: How much?

A: The transmitter will probably cost around $300; the necessary phone case to receive the signal will be in the $75 to $125 range, Rizzone says.

Eventually, though, the idea is that you won’t need either one.

The company says that it has already signed deals with 16 manufacturers, who will build the transmitters into, for example, refrigerators (so your kitchen area will be covered), TV sets (living room coverage), and WiFi routers (office). As you move from area to area, the power transmitters will hand off your gadget from one to the next, just as WiFi is supposed to.


Meanwhile, having to put your phone in a special case is intended to be only a temporary measure, too. Eventually, gadget makers will build the receiving circuitry right into their products, much the way Samsung built charging-mat receiver technology into its Galaxy S4 and S5 phones.

Q: When?

A: Steve told me that they expect these products to be available at the end of 2016 or early 2017. That’s only a year and a half from now!

The nitpicker

But here’s the thing: Energous has a skeptic out there—a reader who’s been emailing me to cast doubt on the demonstration I saw.

First, he spotted what he thought was a little surprise in our video (above). “The video shows that the phone’s charge level dropped from 91% during most of the live interview to 90% near the end of the interview (which was about 4 minutes). So, it appears that instead of charging, the phone is discharging!!!”

And sure enough, he’s right—at least about the phone showing 90% at the end of the video. But was he right that the phone is actually discharging?

We went back to our original footage and figured out that what you’re seeing is not a discharging phone; it’s what’s known in the film biz as a continuity error.

This was a two-camera shoot. One camera was on Rizzone, and one was a “two shot” (framed to show Rizzone and me). We filmed close-ups of the phone after the interview was complete. That’s common practice.

So it was in the editing process that the phone’s percentage-charged indicators got placed out of sequence. In real life, the phone did in fact charge during the demonstration—upward.

But our nitpicker also called my attention to this Fox News interview from 2013. In it, Steve Rizzone guessed that WattUp would be available in the second or third quarter of 2015. And now, of course, he’s estimating dates as late as early 2017.

Of course, complex new tech products get delayed all the time. (Just ask the makers of the Up 3 fitness band, the Pebble Time watch, or Oculus Rift headset.)

But in any case, I asked Steve Rizzone about this. “Yes, the in-market date did change,” he replied. “The reason is actually a sign of progress—the date was pushed back because a Tier 1 licensee [that is, a huge electronics company] has agreed to embed our technology in its products. Embedding naturally creates a longer development cycle, but it will also put WattUp into hundreds of millions of products in a very meaningful way.”

The landscape

There are other RF wireless charging companies out there, by the way. Humavox and PowerbyProxi have come up with charging bowls or boxes, where you put your phone and stuff inside to be charged. (Of course, then you’re back to the charging-mat problem of not being able to use the thing while it’s charging.) 

Powercast’s technology is more like WattUp’s, but seems to be limited to very small trickles of power. (“Our commercially available, FCC-approved transmitter is capable of providing power to devices at distances up to 80 feet,” a spokesperson wrote me. “It is capable of providing hundreds of milliwatts of continuous power.”)

And, of course, there are wireless-charging standards associations like Qi and Rezence, but they’re focused on charging-mat technologies.

WattUp still faces some hurdles: FCC approval. Standards. Building an ecosystem. Price. But I’ve seen it first-hand, and I’m convinced: This technology is real.

But is it coming soon? 

I think I speak for all of us when I say: I sure as heck hope so.

David Pogue is the founder of Yahoo Tech. On the Web, he’s davidpogue.com. On Twitter, he’s @pogue. On email, he’s poguester@yahoo.com. He welcomes non-toxic comments in the Comments below.