A wireless router may someday charge your mobile devices

Energous has developed a WiFi-style wireless charging device that sends power to anything within a 30-foot radius

For all intents and purposes, the new Apple Watch is not a mobile device that uses wireless charging. While its charging cable uses magnetic inductive coupling, the wire must still physically attach to the watch in order to work.

In contrast, George Holmes sees a day not so far from now when smartwatches, smartphones, and other small mobile devices will begin wirelessly charging as soon as they enter a home, office or car. There'll be no need to ever remove that smartwatch from your wrist.

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Holmes, CEO at Energous, is pitching a wireless charging technology called WattUp that can send power in a 15-foot radius using radio frequency transmissions.

The Pleasanton, Calif. company, which raised nearly $25 million when it went public this year, plans to have consumer products out by Thanksgiving, 2015.

So what is it?

The WattUp transmitter works much like a wireless router, sending radio frequency signals that can be received by enabled mobile devices, such as wearables and mobile phones. A small RF antenna in the form of PCB board, an ASIC and software makes up the wireless power receivers.

The Bluetooth wireless communication specification is used between WattUp transmitters and receivers.

Because the amount of wattage it can send is limited, Energous is focused on small mobile devices rather than laptops or batteries that require higher capacities.

A single WattUp transmitter can charge up to 24 devices, all under software control that enables or disables charging. The maximum amount of power -- four watts -- can only be delivered to four devices simultaneously. So as more enabled and "authorized" devices enter a room, the charge to each device is reduced.

Also, as the distance between transmitter and receiver becomes greater, the power transfer dissipates. For example, a WattUp transmitter can stream four watts within a five-foot radius. From five to 10 feet, that power drops to two watts per device and from 10 to 15 feet, the router puts out one watt per device (4 watts total).

Steve Rizzone, Energous' senior vice president of sales and marketing, said that within five feet a mobile device can be charged at the same rate as if it were plugged into a wall socket.

WattUp's RF transmission, which operates at 5.7 and 5.8 MHz, is referred to in the industry as "far-field" wireless charging. Energous is not the first company to come up with the idea.

Startup uBeam landed $750,000 in seed funding for its technology, which uses ultrasound waves to transmit electricity to mobile devices. But the principle is similar to Energous, according to Ryan Sanderson, a principal analyst at IHS.

Wireless charging over distance is nothing new, but most other technologies use magnetic resonance to achieve power transfers at relatively short distances. For example, WiTricity has been licensing its charging technology for use in appliances and the automotive industry.

WiTricity's technology can transmit power between two copper coils that form a magnetic field. But distances from hand-sized transmitters have typically been limited to a foot or so. Devices called "Repeaters" can be used to extend that distance, but generally speaking, the larger the coil, the longer the distance.

Sanderson does not consider WiTricity's technology far-field charging. "Magnetic resonance is near-field wireless charging, no matter how you spin it," he said.

Loosely coupled magnetic resonance technology, offered by Duracell and other manufacturers, enables wireless charging pads that can power up multiple devices at the same time -- as long as they're all placed on the charging surface. That, Sanderson said, is the main problem with magnetic resonance wireless charging. You have to put your mobile device down somewhere for it to charge.

"Those technologies really don't support the notion of mobility," Holmes said. "Mobility is the idea of walking around an office or home and having your device charge passively rather than actively.

"We're not wireless but wire free," he added.

Nick Spencer, a senior director at ABI Research, said the primary concern government regulators will likely have with wireless charging technology is wasted electricity. On average, 40 percent of the electricity sent from a utility's grid into a home is wasted as it moves through various transformers. That loss is greater with wireless charging.

Most magnetic resonance wireless charging devices have an efficiency rating of between and 80 percent and 90 percent, meaning up to 20 percent of the electricity is lost in transmission.

Still, Sanderson and Spencer believe Energous' WattUp technology has massive potential.

Big market appeal

Technology like WiTricity's is already expected to make up the lion's share of the market someday, because it's relatively easy to use.

According to Pike Research, the revenue worldwide from wireless power devices will exceed $15 billion by 2020, and systems based on highly resonant magnetic wireless power transfer will account for more than 80 percent of the overall market.

"I see huge potential for [Energous' technology] as long as it can be proven to work," Sanderson said. "We're seeing a huge increase in wearables. And, the key thing about wearables is that if you have to take them off every day, it becomes a pain. From a consumer point of view, that will be the one thing that makes or breaks that industry."

According to a recent study by IHS, 69 percent of consumers still don't know or understand what wireless charging is. When people think of "wireless," they don't picture the charging pads of today that use magnetic resonance technology.

"What they often conjure up in their minds is a system like Wi-Fi," Sanderson said.

That same IHS study revealed that 78 percent of consumers would purchase a wireless charging accessory and 38 percent would pay to charge their mobile device wirelessly in a public place.

Product partnerships

Energous has been securing partnerhips with tier-two suppliers, the companies that sell parts to big manufacturers like automobile and smartphone makers.

For example, Energous is working with Dialog Semiconductor, a German company that makes integrated circuits for audio and display processing used mainly in mobile phones and the automotive industry. Japan-based Dong-Hwa, one of the world's largest mobile equipment suppliers, is also working to embed WattUp wire-free charging receivers in smartphone cases

Energous has also partnered with rechargeable battery makers such as Highpower International, and is developing reference designs for WattUp-enabled batteries. Holmes sees a day when common objects in a house will have WattUp wireless charging routers embedded in them -- everything from refrigerators, televisions and even picture frames. The company is also working on a smaller charger (less than a one-watt charge) that consumers can place on nightstands to charge wearables as they sleep without having to take them off.

"We decided to go after the low-hanging fruit first. The quickest way to get visibility to the consumer is through enabling battery packs and wearables," Rizzone said.

While Energous has created prototype wireless power routers and receivers, it doesn't plan on selling hardware. Like other wireless power companies, it is licensing its intellectual property for other companies to build into products.

The company plans to demonstrate the first iteration of its product and enabled mobile devices at the Consumer Electronics Show in Las Vegas in January.

"With our solution, you can continue to wear your device 24/7. Your watch will be topped off at night, and that's a significant difference from what Apple offered with its watch this week," Rizzone said.

This story, "A wireless router may someday charge your mobile devices" was originally published by Computerworld.

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