Starbucks' new wireless charging won't work for most devices

Wireless charging wars are likely to limit the technology adoption for the time being

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"The number of consumer devices in circulation that are compatible with Powermat's PMA compared with those built to the longer established Qi specification is, however, still minimal," Sanderson said.

Along with Starbucks coffee shops, McDonald's has also rolled out Powermat pilots in restaurants.

The conflicting and competing standards continue to create uncertainty for mobile device manufacturers looking to adopt wireless charging.

So what's the difference?

There are two types of wireless charging -- loosely coupled magnetic resonance and tightly-coupled inductive charging. Both are based on the same science of creating a magnetic field through which power can be transferred between devices using the same frequency.

The WPC's Qi standard enables inductive or pad-style charging, and the group is working on a specification for short-distance (1.5cm or less) magnetic resonance charging.

The PMA also champions a magnetic inductive wireless charging technology that requires a more tightly coupled link between the charger and device. In addition, the PMA developed an open network API for network services management. So, for instance, Starbucks would be able to identify mobile devices charging in its cafes and gather usage pattners or target users with marketing and advertising.

"The open network API is certainly a valuable part of PMA's offering. It allows for a lot of flexibility and future development," Sanderson said.

In contrast, the A4WP-developed "Rezence" magnetic resonant wireless charging spec allows for a loosely coupled power transfer -- meaning multiple devices can be placed on a charging pad and moved around with little affect to the charge.

The A4WP and the PMA have agreed to share each other's specifications so they can offer both types wireless of charging, but the two technologies are still independent.

The multi-mode charging designs can provide interoperability for future designs, but at an added cost, according to Sanderson.

Mark Hunsicker, senior director of product management at Qualcomm, demonstrates Rezence wireless charging in an IKEA coffee table.

"A developer who wishes to produce something compatible to both standards needs to be a member of both associations, so they both exist very much as single entities still," Sanderson said. "Producing something compatible with both will cost more and provides a reasonable challenge (multiple antennas, separate shielding etc.)."

All three wireless charging consortiums have massive backing from large mobile device manufacturers and consumer product brands.

The Qi specification, however, has the greatest industry support. More than 200 companies, among them a veritable who's who of electronics, such as LG Electronics, Sony, Nokia and Verizon Wireless.

By comparison, the A4WP now has 100 members, including Broadcom, Delphi, Fairchild Semiconductor, Haier, Intel, LG Electronics, Qualcomm, Samsung Electronics, SanDisk, TDK and Texas Instruments. The PMA has 72 members.

Among the tech firms that haven't weighed in one way or the other on wireless charging is Apple.

Long-term, the added premium that multi-standard wireless charging demands is unlikely to allow for mass adoption, said Sanderson, adding that a single mode solution will be required to drive costs down.

Lucas Mearian covers consumer data storage, consumerization of IT, mobile device management, renewable energy, telematics/car tech and entertainment tech for Computerworld. Follow Lucas on Twitter at  @lucasmearian or subscribe to Lucas's RSS feed . His e-mail address is lmearian@computerworld.com.

See more by Lucas Mearian on Computerworld.com.

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