Wireless charging refers to technology and standards that enable consumers to charge electronic devices such as smartphones, tablets and wearable computing products without the need for physical wires.
Wireless charging is made by possible by the principle of electromagnetic induction, in which coils of wire in a charging device create a magnetic field. An electric current flowing through this magnetic field can induce a current in an adjacent coil of wire that can form part of a battery charging circuit in an electronic device, enabling the device’s battery power to be replenished.
While wireless charging is more convenient than traditional wired charging, it typically does so at the expense of efficiency. In most cases wireless charging is only 60% to 70% as efficient as charging with a physical wire, resulting in additional time needed to fully charge a device.
Wireless charging can take two forms: inductive charging, or tightly coupled, in which an electronic device needs to be precisely positioned on a wireless charging pad in able to be charged; and magnetic resonance charging, or loosely coupled, in which multiple devices can be charged at once without the need to place the device(s) in a specific spot and position.
Three Wireless Charging Technologies Competing for Market Share
There are three major technologies competing in the wireless charging scene. The Wireless Power Consortium’s Qi standard has emerged as a global frontrunner in wireless charging, while the Power Matters Alliance’s PowerMat technology has gained prominence in the United States. A third player in wireless charging, Rezence, is backed by the Alliance for Wireless Power (A4WP).
The Power Matters Alliance and the A4WP agreed to share their specifications in February 2014 to help compete against the Qi standard. By the two alliances joining forces, manufacturers can use both loosely coupled and tightly coupled standards in their wireless charging products without customers needing to concern themselves with device and wireless charging station incompatibilities.
And as standards like Qi and the PowerMat have evolved, they have added their own technologies for delivering both loosely coupled and tightly coupled capabilities in the same standard.