Wireless charging

The wireless revolution started in the 1980s and is gradually starting to come of age. A huge landmark of this revolution is Wireless Charging. Before now, when most people think about charging, wires always come to mind. Not anymore. Wireless charging has come and it is here to stay.


What is Wireless Charging?

This can be defined as charging a device without having to physically plug it to a charging cable.


Read: How Smartphone Batteries charge


How it works?

It works by using inductive charging. Inductive charging means using one electrically charged body to create (induce) electricity in another body, inside an electromagnetic field without the two of them touching.

Inside a wireless charger

Inside the charger, there is a magnetic loop antenna (copper coil wound around a magnet). When electric current is supplied to the charger, it creates an electromagnetic field that induces current in a receiver coil on the phone.

Wireless receiver coil in a phone

Types of wireless charging

There are three types of wireless charging:

  1. Tightly coupled electromagnetic inductive coupling (non-radiative charging)
  2. Loosely coupled electromagnetic resonant coupling (radiative charging)
  3. Uncoupled radio frequency wireless charging (trickle charge)

Tightly coupled electromagnetic inductive coupling (non-radiative charging)

This type of charging requires that the phone be placed exactly over the magnetic loop in the wireless charger. If it is not placed properly, the device won’t charge properly and sometimes not at all.

Loosely coupled electromagnetic resonant coupling (radiative charging)

Electronic magnetic resonant coupling means the addition of capacitors to both the magnetic loop antenna on the charger and the receiver coil on the phone. This increases efficiency and power delivery during charging. In this case, you do not have to place the phone at a particular spot so it can charge. You can place it anywhere on the wireless charging pad and it will charge just fine.
Radiative charging is better (i.e. faster and more efficient) than non-radiative charging.

Uncoupled radio frequency wireless charging (trickle charge)

This type of charging does not require the phone to be anywhere near the charger at all, but only within a certain range. This type of charging is very convenient but it is also very slow.


Read: Fast Charge explained


Wireless Charging Standards

There were three main standards for wireless charging. They were Alliance for Wireless Power (A4WP), Power Matters Alliance (PMA) and the Wireless Power Consortium (WPC).

The Wireless Power Consortium (WPC) which is made up of Google, Apple, Verizon and other big manufacturers became the dominant force in the market and put out the Qi (pronounced as ‘Chee’) standard. Qi is the most widely used charging standard in the world today.

In order to challenge WPC’s Qi, the A4WP and PMA decided to combine and form an entirely new standard. This standard is known as the Air Fuel Alliance (AFA). It is made up of big names such as Dell, Duracell, Samsung, Qualcomm etc. The charging standard known as Powermat was pushed by the AFA as a challenger to the Qi standard. The two charging standards are not compatible with one another.

Qi remains the main charging standard in the smartphone world. WPC also allows different OEMs to modify their Qi technology. This has given birth to the rise of several proprietary charging technologies that play well with one another.

A lot of different charger and powerbank manufacturers have taken advantage of it. There are now different types of wireless charging pads as well as powerbanks in the market today. Xiaomi currently has the fastest wireless charging with their 65W wireless charger requiring just 33 mins to fully charge the MI 11 Ultra.

Xiaomi have also taken things further with their Air charge technology which guarantees 5W wireless charging from every part of your home.


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