Qi (pronounced “Chee”) is the brand name of the wireless charging platform developed by the Wireless Power Consortium (WPC), an open-membership group made up of companies in Europe, Asia and the United States. The WPC was founded in 2008 with the mission to create a universal standard in wireless charging.
Qi allows for a device to be recharged simply by placing it on top of a charger, as opposed to plugging it in. Electricity is transmitted from the charging pad to the device via inductive charging coils contained in both, that are tuned to the same frequency. This is called “resonant inductive coupling.”
As related to Windows Phone, Qi charging can be found in a number of devices. Nokia included Qi charging in a number of its Lumia line of phones:
- Lumia 735
- Lumia 810
- Lumia 830
- Lumia 920
- Lumia 928
- Lumia 930 (Icon)
- Lumia 1520 (non-AT&T version)
Other Lumia phones had the option to add a backplate that would allow the device to be charged wirelessly:
- Lumia 720
- Lumia 820
- Lumia 822
- Lumia 925
- Lumia 1020
HTC included Qi charging in its 8X on Verizon.
Despite the WPC’s intent to universalize wireless charging technology, Qi does have its competitors. Most notable of them is the Power Matters Alliance, or PMA, which was founded in 2012 by Proctor & Gamble and Powermat Technologies. PMA has some heavy backers, like Microsoft, AT&T, Samsung and Starbucks, but has yet to supplant Qi as the market leader.
Qi v1.2 is the latest generation of Qi charging. It allows the delivery of power over a distance of up to 45mm, greatly surpassing that of the former generation, which topped out at a distance of 7mm. This greatly increases the possibilities for embedding Qi charging into objects, like furniture, vehicles, etc. Furthermore, the v1.2 standard makes it possible for a single inverter to power multiple coils. These two new features have been combined to create charging boxes, containers that multiple devices can be placed in together to charge at the same time.
As of October 2014, Qi 1.2 has yet to launch commercially.