WIRELESS CHARGING EXPLAINED

Electromagnetic induction recharges smart phones, connected watches and modern headphones without wires to connect. A short practical guide to take full advantage of it.

Wireless charging has been around for years, whether in electric toothbrushes, phones, robot vacuums or wireless headphones. Even if the foundations of induction have been known for a long time - the inventor Nikola Tesla experimented with this technology at the turn of the twentieth century - his recent adoption in more and more varied devices is leading to a renewed interest in techno industry.

How It Works ?

The inside of a wireless charger launched five years ago. Recent advances make it possible to produce chargers that are both smaller and more powerful.
Wireless charging uses an electromagnetic field to transfer energy from one device to another. The field is created when electricity passes through a coil in the charger, and the energy is converted back into electricity through a second coil, placed in the compatible device. Wireless charging as we find it today in electronic devices only works at a very short distance; so, for example, you have to place your smartphone directly on the charging surface for the energy to be transferred.

Health and Electromagnetic Induction

Several studies have explored the effects of electromagnetic fields on health in recent decades, especially in relation to cell phones. Most scientific research indicates that the doses humans are normally exposed to do not seem to have a harmful effect on their health. Note also that the intensity of the fields created by the wireless chargers decreases rapidly when moving away, which minimizes the risk.

Different Models of Chargers

Compatible electronic devices, such as Apple's iPhone XS smartphone, Google's Pixel 3 and Samsung's Galaxy S10, are often sold without a wireless charger. Consumers must therefore find a compatible model that suits them. These are offered in different formats.

Chargers are usually sold with one or two charging surfaces, which can be flat (which is more convenient for putting on a headphone case, for example) or upright (so that you can see your phone more easily while charging).

The unit should be placed in a fairly precise position to align the coils and ensure that the energy transfer is working. So not all phone formats are compatible with all forms of charger. Note that Apple had tried to work around this problem by creating a charging pad called AirPower (the image at the top of the ticket), where up to three devices could be placed without precise alignment. The company, however, abandoned the creation of its product last Friday, a year and a half after its announcement, citing insurmountable technical problems.

In addition to personal chargers for the home, there are also optional wireless charging surfaces in a large proportion of new motor vehicles, Ikea furniture and airports.

Are All Devices Compatible?

The majority of wireless charging devices launched in recent years are compatible with the Qi standard. The charger built into the BMW X5 2019, for example, supplies as much a Samsung phone as a Google pixel or Apple's AirPods 2 headphones.

There are some exceptions, however. Smart watches, even if they use similar charging technologies, often have their own protocol, and therefore require their own chargers.

5 W, 7.5 W, 15 W: Not All Chargers Are Equal

Not all smartphones have the same wireless charging power. The new iPhone can take advantage of 5-watt and 7.5-watt chargers, while Samsung's new Galaxy phones can be recharged even faster with a 12-watt charger. The Huawei P30 Pro, announced last week, pushes the bar even further, with a wireless charging of 15 watts.The more powerful a charger is, the faster the recharge will be, provided the device on it can enjoy it. However, the speed is generally lower than regular wired charging.

Note also that a 15-watt charger will not be three times faster than a 5-watt charger, for example. Wireless charging actually heats electronic devices. To avoid damaging them, the power of the charge decreases as the temperature increases. A 15 watt charger can start at full power, but quickly down to the speed of a 5 watt charger.

The Future of Wireless Charging

Future wireless charging standards will be powerful enough to power small appliances.
More than 500 million electronic devices are compatible with Qi wireless charging worldwide, including a large majority of phones. Technology, however, has an interest that goes far beyond personal gadgets.

The Wireless Power Consortium, the organization behind the Qi protocol, is working on new standards to regulate small appliances in the kitchen. It will then be possible to simply place his compatible food processor on a surface embedded in his countertop to activate it.

Wireless charging could also soon be used to power hard-to-reach medical devices such as pacemakers. Wireless charging could also be integrated into road pavements to recharge city buses throughout the day while parked at stops, for example.

Several companies are also currently developing new charging protocols operating over greater distances, for example to charge any device in a room. However, it took a decade after the launch of the Qi protocol for it to be adopted by the general public. It will probably be necessary to wait a long time before such uses are transposed from laboratories to everyday life.