How wireless charging works for a phone: it’s not magic

How wireless charging works for a phone: it’s not magic

In recent years, wireless charging smartphones are finding more and more fans. There are already more than 500 models of various devices on the market that support this method. Perhaps you have been using it for many years if you have an electric toothbrush: just put it on the dock – it will start to charge.

The principle of charging your smartphone or smartwatch is the same. Very practical, no need to connect the cable. But what is wireless charging and how does it work?

The secret to electromagnetic induction

wireless charging
wireless charging

How can energy be transferred from one thing to another? Wireless charging works by the principle of electromagnetic induction. This phenomenon was first described in 1831 by Michael Faraday, who discovered that if a magnetic field source was moved through a coil, an electric current would appear in it. Michael Faraday found a relationship between electricity and magnetism.

How electromagnetic induction works is easy to explain by performing the following experiment:

  • Take the magnet from the refrigerator.
  • Connect the bulb to a simple copper coil.
  • Move the magnet back and forth inside the coil.
  • The lamp will light up!

Why did the light come on? By conducting a magnet inside the coil, you changed the magnetic field created by it. These vibrations were felt by a coil in which an induced current was generated.

How is wireless charging

In fact, wirelessly charging your smartphone or other device works the same way as we saw in the light bulb experiment. Of course, there is no moving magnet, but there is an induction coil through which high-frequency alternating current flows.

wireless charging
wireless charging

This current generates changes in the magnetic field . This part of the wireless charging system is called a “transmitter-coil . ” The part located inside your phone is called the “receiver coil”, and current flows through it the same way as through the coil in the experiment.

Is wireless charging safe?

Magnetism is always perceived as something akin to magic, because magnetic fields cannot be seen. To build an effective wireless charging system, it is necessary to concentrate themagnetic field around the transmitter coil.

This effect is achieved using special materials – ferrites , which conduct a magnetic field much better than air. Therefore, it is easier for a magnetic field to pass through ferrite rather than look for other propagation paths. Thus, outside the charge, the magnetic field is practically absent, and it is completely safe .

Fast or slow?

Is it possible to charge the device using wireless charging as fast as through a wire? A 5 W wireless charging system will be able to charge the device at a speed equivalent to wire charging, operating at a voltage of 5V and a current of 1A.

Recent developments in the field of contactless charging can do this even faster: up to 15 watts can be fed to the phone. This significantly reduces charging time, wireless fast charging is becoming increasingly popular.

Which smartphone can be charged wirelessly?

wireless charging
wireless charging

Today on the market there are more than 500 models of devices with support for wireless charging.

Recent Apple models have this feature. Samsung and Nokia also integrated it a few years ago. The companies included in the Wireless Power Consortium also support wireless charging technology . The following list of models into which WPC or Qi technology is integrated is not exhaustive, but it gives some idea of ​​the market:

  • Apple Wireless Charger supports iPhone 5 / 5C / 5S, iPhone 6/6 Plus / 6S / 6S Plus, iPhone 7/7 Plus, iPhone 8/8 Plus, iPhone X, iPhone Xs
  • Samsung Wireless Charger: Galaxy A7, Galaxy A9, Galaxy J7, Galaxy A310, Galaxy S6 / S6 Edge / S6 Edge Plus, Galaxy S7 / Edge S7 / S7 Edge Plus, Galaxy S8 / S8 Plus, Galaxy S9 / S9 Plus
  • Huawei Wireless Charger: P8, P8 Lite, Mate 8, P9, P9 Lite
  • LG Wireless Charger: G3, G4, G5, Stylus G4, K10
  • Sony Wireless Charger: Xperia Z5, Premium Z5, Compact Z5, Xperia X, Xperia XA
  • Nokia Wireless Charger: Lumia 950, Lumia 650
  • HTC Wireless Charger: One X9
  • Motorola Wireless Charger: Moto X, Moto G

By the way, you can check whether your smartphone supports Qi technology by checking on the Consortium website. If you have a different model, do not panic. In this case, you just need to buy a special receiver in addition to the charger , which should be placed next to the batteries of your gadget.

The disadvantages of wireless charging

If wired chargers simply disappear between charging cycles, then when using contactless charging, the user encounters other disadvantages.

  • Depending on the size of the charging surface, you can charge two or more devices at the same time, but such chargers are more expensive.
  • Charging can be done remotely, but you still need to be close to charging – do not take the device further than 4cm.
  • Nonetheless, remote charging takes more time than the contact method, since electricity is “lost”. Therefore, it is better to hold the phone only on the charger plate.

The future of wireless charging

Currently, the maximum wireless charging power is 15 watts, so such devices are designed exclusively for smartphones, cameras and smartwatches. The Wireless Power Consortium, however, is working to improve the Qi technology so that it can be used to charge devices with more capacious batteries, such as computers or electric cars.

Such technology already exists, it is in the phase of testing and market adaptation. It was developed by WiTricity and is powered by magnetic resonance technology. In fact, the same thing happens as when charging Qi, but at a greater distance. Since the largest market for electric cars today is in China, the manufacturer cooperates mainly with this country.