Wireless rechargeable phones

Wireless mobile charging is a feature where you can charge your mobile without plugging in cables. However, the charger you place your phone on must have a cable plugged in. Below are all the advantages and disadvantages of wireless charging as well as some techniques and a bit of history.

Advantages of wireless charging

The overwhelming advantage of wireless charging is that you no longer need to plug a cable into your phone to charge it. Instead, you place the device on the charger. This is handy in the dark where you have no light to find the charging port. It also keeps your mobile nice for longer because plugging in the connector every time can damage your device. In theory, it could even be possible to make a completely port-free phone where no dust, dirt or water can enter.

Disadvantages of wireless charging

Wireless charging also has drawbacks. For instance, wireless charging is slower than wired charging. Energy is also lost in the charging process, making it slightly less efficient and therefore more expensive to use. Some of these disadvantages have largely been addressed in recent years. For instance, nowadays you have wireless fast chargers and thanks to newer technology, energy loss has also been minimised. Another point that can be perceived as a disadvantage is that the phone has to be close to the wireless charger. Ideally, they should be touching each other. So it is not possible to charge your phone from one side of the room.

Stands

Like charging cables, there are different standards for wireless chargers. For mobile phones and other consumer electronics, there are currently two main ones;

• Qi
• PMA

The most well-known is Qi (pronounced sjie). This technique was developed by the Wireless Power Consortium (WPC). Most phones that can be charged wirelessly support this standard, think 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) into the AirFuel Alliance in 2015, the PMA name has stuck. The two standards work pretty much the same way; via induction. To make it easy for manufacturers, most mobile phones support both Qi and PMA. Before buying a wireless charger, check beforehand whether your mobile really supports it; as they are not completely compatible.

Current phone wireless charging

If your current mobile phone does not support wireless charging, there is still an option to charge it wirelessly. Via a case. Such cases have come out of some popular models that do not come with wireless charging. Type in the name of your phone in Google followed by 'wireless charging case'. These days, we see manufacturers now equipping their expensive flagships 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. That's because the process of wireless charging can easily be reversed. In this, your mobile gives the energy away instead of receiving it. For example, place your AirPods on your mobile to charge them. You can also give away power to other phones by placing them against each other. Not every phone with wireless charging supports this feature. So that is something to watch out for if you are specifically looking for this.

Wireless fast charging

Wireless charging is slower than via a cable. To alleviate this problem, methods have been devised to speed it up. Wireless fast chargers can be recognised by the fact that they have more than 5 watts as output. Fast chargers of 10 Watts roughly halve the charging time. However, if you want to be back on the road in 15 minutes or less, there is no escaping the wired fast chargers.

Operation

Wireless charging works on the basis of resonant induction. Inside the phone is a coil; a wrap of copper wire. This captures a magnetic field and converts it into current that is used to charge the battery. The magnetic field is in turn generated by passing current through a coil. The wireless charger usually contains several of these coils to increase the surface area that can be charged. This principle only works if the transmitter and receiver are reasonably close together (maximum 4 centimetres) and are not interrupted. This is therefore the reason why wireless charging phones do not have a metal back but rather glass or plastic.

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

History of wireless charging

The principle of transmitting power wirelessly was discovered as early as 1831. However, it lacked the means to put it into practice. It was Nikola Tesla who carried out the first experiments with wireless power between 1890 and 1906. However, it never came to an actual marketable product. Meanwhile, discoveries and experiments in induction continued. The need for wireless charging became clear for consumer electronics in wet areas like the bathroom.

Mobile phones also proved very suitable for wireless charging, especially since they need to be charged so often and fiddling with cables is just tedious. In 2008, the Wireless Power Consortium was formed. Its aim was to come up with a standard that every manufacturer would adhere to. This became Qi, which came out in August 2009. It was Palm that had the honour of announcing the first mobile with wireless charging; the Palm Pre. Other manufacturers followed only years later. Nokia released the Lumia 920 in 2012, while Samsung did not release its first mobile until 2016; the Galaxy S6. These days, you don't belong as a manufacturer if at least your flagship does not come with wireless charging.