Wireless rechargeable phones

Wireless charging of your mobile phone is a feature that allows you to charge your phone without plugging in any cables. However, the charger on which you place the phone must have a cable plugged into it. Below you will find all the advantages and disadvantages of wireless charging, as well as some of the technologies involved and a brief history.

Advantages of wireless charging

The main advantage of wireless charging is that you no longer need to plug a cable into your phone to charge it. Instead, you simply place the device on the charger. This is handy in the dark when you don’t have a light to find the charging port. It also helps keep your mobile in good condition for longer, as repeatedly plugging in the connector can damage your device. In theory, it might even be possible to create a completely port-free phone that’s impervious to dust, dirt or water.

Disadvantages of wireless charging

Wireless charging also has its disadvantages. For one thing, wireless charging is slower than wired charging. Energy is also lost during the charging process, making it slightly less efficient and therefore more expensive to use. A number of these disadvantages have been largely addressed in recent years. For example, wireless fast chargers are now available, and thanks to newer technologies, energy loss has also been minimised. Another point that may be seen as a drawback is that the phone must be close to the wireless charger. Ideally, they should be in contact with each other. It is therefore not possible to charge your phone from one side of the room.

Standards

Just like charging cables, there are also various standards for wireless chargers. For mobile phones and other consumer electronics, there are currently two main ones;

• Qi
• PMA

The best known is Qi (pronounced ‘chee’). This technology was developed by the Wireless Power Consortium (WPC). Most phones capable of wireless charging support this standard, such as those from Apple and Samsung. The other standard is PMA, which stands for Power Matters Alliance. Although that organisation merged with the Alliance for Wireless Power (A4WP) in 2015 to form the AirFuel Alliance, the PMA name has stuck. The two standards work in virtually the same way: via induction. To make things easier for manufacturers, most mobile phones support both Qi and PMA. Before buying a wireless charger, check in advance whether your mobile actually supports it; they aren’t entirely compatible.

Wireless charging for your current phone

If your current mobile phone doesn’t support wireless charging, there’s still a way to charge it wirelessly. Using a case. Cases like this have been released for some popular models that weren’t originally launched with wireless charging. Type the name of your phone into Google followed by ‘wireless charging case’. These days, we’re seeing manufacturers equip their expensive flagship models with wireless charging as standard.

Reverse wireless charging

A relatively new feature in the world of wireless charging is reverse wireless charging. This allows you to charge another device instead of your phone. This is because the wireless charging process can easily be reversed, so your mobile phone gives out energy rather than receiving it. For example, you can place your AirPods on your mobile phone to charge them. You can also transfer power to other phones by placing them against each other. Not every phone with wireless charging supports this feature, so it’s something to bear in mind if you’re specifically looking for this.

Wireless fast charging

Wireless charging is slower than charging via a cable. To mitigate this issue, methods have been devised to speed up the process. Wireless fast chargers can be recognised by their output of more than 5 watts. 10-watt fast chargers roughly halve the charging time. However, if you want to be back on the road in 15 minutes or less, you’ll have no choice but to use wired fast chargers.

How it works

Wireless charging works on the principle of resonant induction. Inside the phone is a coil – a winding of copper wire. This picks up a magnetic field and converts it into current, which is used to charge the battery. The magnetic field is, in turn, generated by passing a current through a coil. The wireless charger usually contains several of these coils to increase the surface area over which charging is possible. This principle only works if the transmitter and receiver are reasonably close to each other (up to 4 centimetres) and there is no interruption. This is why wireless-charging phones do not have a metal back, but are instead made of glass or plastic.

There are other ways to transfer power wirelessly. Examples include ordinary induction (electric toothbrushes and kettles), capacitive charging (smart cards), dynamic charging (electric cars), microwaves (satellites) and light waves.

History of wireless charging

The principle of wireless power transmission was discovered as early as 1831. However, the means to put this into practice were lacking. It was Nikola Tesla who, between 1890 and 1906, carried out the first experiments with wireless power. However, it never resulted in an actual marketable product. Meanwhile, discoveries and experiments in the field of induction continued. The need for wireless charging became apparent for consumer electronics in damp areas such as the bathroom.

Mobile phones also proved to be very suitable for wireless charging, particularly as they need to be charged so often and fiddling with cables is a nuisance. In 2008, the Wireless Power Consortium was founded. Its aim was to devise a standard that every manufacturer would adhere to. This became Qi, which was launched in August 2009. It was Palm that had the honour of announcing the first mobile phone with wireless charging: the Palm Pre. Other manufacturers did not follow suit until years later. Nokia released the Lumia 920 in 2012, whilst Samsung didn’t release its first mobile until 2016: the Galaxy S6. These days, a manufacturer is considered out of the loop if its flagship model isn’t equipped with wireless charging.