Wireless charging is set to become more popular with the adoption of Qi wireless charging in Apple’s iPhone 8, iPhone 8 Plus, and iPhone X. It’s also found on some Android phones, like Samsung’s Galaxy Note 8, Galaxy S8, and Galaxy S7. But how does it work exactly? Not by magic but more of science…
Most wireless chargers use magnetic induction and magnetic resonance. They offer the promise of being able to place a device on a surface and have it charge automatically—no fiddling with cables required. Wireless charging isn’t truly wireless, of course. Your phone, smart watch, tablet, wireless headphones, or other device doesn’t need to be plugged into the charger with a wire, but the wireless charger itself still has to be plugged into a wall outlet to function. When the iPhone 5 was released without the wireless charging feature found in competing Android and Windows phones at the time, Apple’s Phil Schiller argued that “having to create another device you have to plug into the wall is actually, for most situations, more complicated”.
Five years later, Apple has changed its mind. With the iPhone 8, iPhone 8 Plus, and iPhone X, Apple is including support for wireless charging using the Qi open standard. (It’s pronounced “chee” as it’s a Chinese word that refers to the “life energy” in living things.)
Wireless chargers typically use magnetic induction. The short explanation is that they use magnetism to transmit energy. First, you place the device–like a smartphone—on the wireless charger. The current coming from the wall power outlet moves through the wire in the wireless charger, creating a magnetic field. The magnetic field creates a current in the coil inside the device sitting on the wireless charger. This magnetic energy is converted to electrical energy, which is used to charge the battery. Devices must have the appropriate hardware in them to support wireless charging—a device without the necessary coil can’t charge wirelessly.
While the Qi standard was originally limited to magnetic induction, it now also supports magnetic resonance. This works similarly, but the device can be up to 45mm away from the wireless charger’s surface rather than touching it directly. This is less efficient than magnetic induction, but there are some advantages—for example, a wireless charger could be mounted under a table’s surface and you could place a device on the table to charge it. It also allows you to place multiple devices on a single charging pad, and have all of them charge at once.
Wireless charging is becoming more and more common, and even more standardized. And for once, Apple didn’t create its own wireless standard. Instead, it chose to support the existing Qi standard, which many other devices also support.
However, Qi isn’t the only standard around. The Qi standard, which is owned by the Wireless Power Consortium, is ahead, but it’s not alone. In second place is the Power Matters Alliance’s Powermat, or PMA, standard. It uses magnetic induction, like Qi. The two are incompatible, though. An iPhone can’t charge with a PMA wireless charger.
The Alliance for Wireless Power (A4WP)’s Rezence uses magnetic resonance instead, a feature Qi added later. Yes there is actually an Alliance for this stuff! This allows for greater freedom of positioning. You can have multiple devices on a single charger, move devices around, and even charge devices through an object like a book between the device and the charger. Rezence requires Bluetooth to communicate with the device.
Once you have a phone or adapter that supports wireless charging, pick up a wireless charger that’s compatible with it. For most phones, you’ll want a Qi charger. Any Qi certified wireless charger should work with any Qi certified device. You can find them online on websites like Amazon.com or in electronics stores. Plug the charging pad into the wall and place your phone (or other Qi-enabled device) on it to charge. As long as your device and the charger support the same standard, it will just work.
In the future, wireless chargers will hopefully be more common in public locations, allowing you to just place your smartphone on a table to charge it. Hopefully coffee places like Starbucks (known as the third space anyhow in terms of their branding) will offer it so that you can finally walk freely with any more cables. Either that or phones will simply have to make batteries with bigger capacities!
Enjoy the music!