Cutting the cable: Wireless charging becomes a reality

Qi standard, emerging technology bringing wireless mobile device charging capabilities to PCs, furniture and cars

Imagine sitting down at work, plopping a mobile device on the desk and having it wirelessly charge itself while, at the same time, synchronizing new data to your PC.

In that world, one could also wirelessly charge a phone set on a car's dashboard or armrest while it plays music through the speakers, and never have to search for the one open electrical outlet at the coffee shop or airport.

That world may not be too far off for the masses of smartphone, tablet and other mobile device users.

With the launch of the Windows Phone 8-based Lumia 920 smartphone last week, embedded wireless charging is hitting the U.S. mainstream.

The built-in wireless charging capabilities offered in the Nokia 920 doesn't require that widgets be plugged into the USB port of a smartphone in order to charge it from a magnetic induction power pad. That's the typical wireless charging process today.

The Lumia 920 only has to be laid on a power pad to be charged.

Charging Pads

William Stofega, an IDC mobile device analyst, said wireless charging pad business is currently dominated by Duracell's Powermat technology, which is based on magnetic induction technology, one of two forms of wireless charging.

Duracell's Powermat wireless phone charger

But that choice is likely to change soon, thanks in part to the Wireless Power Consortium's Qi (pronounced "chee") open wireless charging standard, Stofega said.

Already, some products from 120 companies are certified as compliant with the Qi standard.

The certified products run the gamut, from the LG Optimus LTE2 and Panasonic Eluga smartphones, to charging pads, gaming controllers, Blu-ray Disc recorders, smartphone docking speakers, automobile phone chargers, alarm clocks, battery packs and charging modules that can be installed in tabletops and furniture.

Magnetic induction vs. resonance charging

Analysts note, though, that there are some slight differences in the Qi-compliant wireless charging products being developed today.

Some use magnetic induction charging techniques, which require that the mobile device be in contact with a charging device. Others use resonance charging, which allows a mobile device to be placed near the power source for charging.

Magnetic induction charging uses two coils: a transmitter coil and a receiver coil. Alternating current in the transmitter coil generates a magnetic field, which induces a voltage in the receiver coil.

In contrast, resonance charging offers wireless AC transmission to a device at a distance ranging from 5mm to 40 millimeters (about 1.5-in) from the power source.

Resonance charging is based on the same transmitter/receiver coil technology as magnetic induction, but it transmits the power at a greater distance. So, for example, a mobile device could be charged when laid next to a laptop with resonance charging capability.

To date, there are no resonance-charging devices available, according to Stofega. But that may soon change as Intel ramps up its wireless chip development.

Intel Labs first demonstrated in 2008 technology that could wirelessly charge mobile devices. Intel's Wireless Charging Technology (WCT) would let a user charge a smartphone wirelessly from a notebook PC. Intel late last month announced a partnership with Integrated Device Technology Corp. (IDT) to develop chipsets for WCT products.

Products using the chipsets are expected to come out in 2013, Intel said.

Some reports have said the next Apple MacBook laptop will have wireless charging capability based on the Intel-IDT technology.

"[The jointly developed] product is important and new because it leads to a solution that isn't limited to inductive charging and 'smartphone on a charging mat' usage," Intel spokesman Dan Snyder wrote in a blog post.

"Although we are not yet giving out timeframes for consumer products with WCT enabled, IDT has stated they will be delivering their full chipset solution for reference design work in early 2013," Snyder added. "The ecosystem is already excited about this technology so we assume there will be a race to the finish line for sure."

Currently, wireless chargers can supply up to 5 watts of power, the equivalent of most USB-style chargers available today. By comparison, a USB port on a laptop, which shares it's bandwidth with data I/O, offers only 2.5 watts of power.

Some of the latest USB chargers, however, offer fast charging with 10 watts of power.

The Wireless Power Consortium is already working to extend its Qi specification to allow 10 watt power charging, said Menno Treffers, chairman of WPC.

"In the U.S., you're seeing smartphones [with wireless charging] taking off this quarter," Treffers said. "Europe will be a little later than the U.S."

In Japan, where the wireless charging market is more mature, several companies have put out combination products, where a single system can be used to charge a device while transferring data.

For example, TDK this week released a Bluetooth enabled speaker that also uses magnetic induction to power mobile phones while also playing music stored on them.

Wireless charging speaker
TDK's wireless charging speaker

Treffers said automobile manufacturers can be expected to add wireless charging technology to cars.

"The automobile industry needs to start now because there's a long [development] lead time," Treffers said. "If you want wireless charging in your car this year, you would have had to have started production last year."

The Qi standard

The Qi symbol that will appear on products

The Wireless Power Consortium published the version 1.1 of the Qi open wireless charging standard in March, 2012.

Laptops and charging devices supporting the standard can charge mobile devices that are placed on, or near them using either magnetic induction or resonance charging.

According to WPC, there are 8.5 million Qi capable devices sold worldwide. The largest market for wireless charging is Japan, where it's almost impossible to purchase a mobile phone without the capability embedded in it, Treffers said.

Gartner analyst Ken Dulaney called the Qi standard "a strong, and sorely needed means for wireless charging."

Though several key vendors, including Apple and Samsung, have yet to announce support for the Qi Standard, Dulaney believes it already has the necessary backing to move forward.

According to Intel, an Ultrabook user could soon simply use WCT detection software on a PC to charge a nearby smartphone. Coupling takes place between the two devices and energy begins to seamlessly and wirelessly flow from the Ultrabook to the smartphone.

"Within an hour, you have recharged your smartphone sufficiently to make it through the afternoon. No more wires or chargers," Intel said.

The Qi specification is also aimed at technology used automotive systems to avoid interference with wireless systems like Bluetooth. The Qi standard also is expected to be adopted by wireless payment systems, combining powering and data transfer.

"The technology has improved to the point where it takes just about as long to charge your device wirelessly as it does with a cable," Dulaney said. "And combined with Bluetooth you really could see a day where you could give up the cables in your bag."

Lucas Mearian covers storage, disaster recovery and business continuity, financial services infrastructure and health care IT for Computerworld. Follow Lucas on Twitter at @lucasmearian, or subscribe to Lucas's RSS feed . His e-mail address is

Copyright © 2012 IDG Communications, Inc.

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