Apple AirPower charging plate uses Qi protocol, but may not be compatible with other devices
Apple's AirPower charging plate will charge three Qi devices, and appears to be the first plate that takes advantage of the protocol's ability to deal with multiple devices on the same charger by sensing the location of the device, and only inducing a charge in those locations.
At present, the most common Qi implementation allows for one device to be charged by one base station. As an example, the Belkin charging plate, announced on Tuesday, adheres strictly to that requirement.
There is no specific order for devices on the device, and it appears at this time that a Series 3 Apple Watch, the AirPods Wireless Charging Case, and a compatible iPhone can be placed nearly anywhere on the pad.
This is allowed implicitly by the Qi standard — it just appears that nobody else has done it the way that Apple is, just yet.
How Qi works
The Qi standard relies on induction between two coils to deliver power to a device that needs charging. The base station contains a transmitting coil that generates a oscillating magnetic field, which induces an alternating current in the receiving field.
The coils are aligned with each other in either guided positioning relying on the user to place a device in a specific position and alignment, or hardware can be built allowing for free positioning.
Free positioning is generally used in most charging plates, with relatively minor adjustments made by magnetic positioning or other mechanical apparatuses.
Other multiple device Qi charging pads like the Incipio Ghost 220 still have specific locations, and are using multiple coils in one charging unit.
Qi also allows for free positioning to be implemented by inducing a magnetic field just at the location of the receiving coil with multiple cooperative flux generators. Devices put on a plate communicate their location, and the field is only induced under the device by the flux generators operating in tandem.
Apple appears to be using this method for a trio of devices that can be placed in any order, on any location on the pad.
Pay it forward?
Apple is a member of the Wireless Power Consortium, and has been since February. It has been using an off-shoot of the Qi technology in the Apple Watch prior to the Series 3, albeit made proprietary by MFi-based authentication.
The Wireless Power Consortium trumpeted the release of the technology in the iPhone 8, iPhone X, and Series 3 Apple Watch. In a statement, an executive for the group claimed that Apple's inclusion is paving the way to "ubiquitous access to wireless charging."