How do wireless charging pads work?

Wireless charging works by transferring energy from the charger to a receiver in the back of the phone via electromagnetic induction. The charger uses an induction coil to create an alternating electromagnetic field, which the receiver coil in the phone converts back into electricity to be fed into the battery

Wireless charging pads make use of coils to create the electromagnetic field that is used to transfer energy from the charging base to the device. An induction coil within the charger forms an oscillating magnetic field, while a secondary coil (on the receiving wireless charging-enabled device or receiver case) obtains power from the field and converts it into the electric current that is used to recharge a device. These coils generally have slightly off-resonance frequencies to allow highly-efficient power transfer, which means with chargers that use inductive coupling, the coils have to be properly aligned for efficient charging.

It’s also important to note that wireless charging pads contain coils that are small in diameter (a few inches). The diameter of the coils directly affects the distance between the device and your phone, which means bigger coils will be able to transfer more energy—thus resulting in faster charging speeds.

In order to better explain how wireless charging pads work, here’s a simple illustration from TDK:
Simply put, you’ll have to plug your charging pad to a wall socket and place your Qi or PMA-compatible device on top of it. As long as your receiver (wireless charging-enabled device or receiver case) is properly aligned with your charging pad, you’re good to go. Accurate placement and alignment is essential to ensure fast and efficient charging, so you may want to check if your wireless charging pad uses magnetic power to immediately guide your phone to the best charging spot. If it doesn’t, some manufacturers are now producing magnetic wireless charging cases to help you achieve proper placement every time you charge.