Wireless rechargeable phones

Wireless mobile charging is a feature where you can charge your mobile without plugging in cables. However, the charger you put the 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 have to plug a cable into your phone to charge it. Instead, you place the device on the charger. This is convenient in the dark where you don't have a light to find the charging port. It also keeps your cell phone looking nice longer because plugging in the connector every time can damage your device. In theory, it might 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 disadvantages. For example, wireless charging is slower than wired charging. Also, energy is 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 example, today you have wireless fast chargers and thanks to newer technology, energy loss has also been minimized. 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 cell phones and other consumer electronics, there are currently two major 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 organization merged with the Alliance for Wireless Power (A4WP) in 2015 to form the AirFuel Alliance, the PMA name has stuck. The two standards work pretty much the same way; via induction. To make it easy for manufacturers, most cell phones support both Qi and PMA. Before you buy a wireless charger, check beforehand whether your mobile really supports it; as they are not completely compatible.

Current phone wireless charging

If your current cell phone does not support wireless charging, there is still a possibility to charge it wirelessly. Via a case. Such cases have come out of some popular models that do not come with wireless charging. Type into Google the name of your phone followed by "wireless charging case. Nowadays, we see that manufacturers are now equipping their expensive flagships with wireless charging by default.

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 process, 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 laying them against each other. Not every phone with wireless charging supports this feature. So that's something to watch out for if you're 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 identified by having 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 to current which 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 area that can be charged. This principle only works if transmitter and receiver are reasonably close together (maximum 4 centimeters) and not interrupted. This is why wireless charging phones do not have metal backs but rather glass or plastic.

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

History of wireless charging

As early as 1831, the principle of wirelessly transmitting power was discovered. However, it lacked the means to put it into practice. It was Nikola Tesla who conducted the first experiments with wireless power between 1890 and 1906. However, it never came to 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 wet areas such as the bathroom.

Cell phones also proved to be well suited for wireless charging, especially since they need to be charged so often and fumbling with cables is just tedious. In 2008, the Wireless Power Consortium was formed. Its goal 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 honor 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 equipped with wireless charging.