Wireless charging explained! Everything you need to know

Wireless charging explained! Everything you need to know
Wireless charging. It's magic. It's a testament to technological progress. It's pure science fiction! Okay, let's cut the drama a tad. You get home, you decompress, and you throw your smartphone on the charging pad. What's actually happening? How does all this energy jump from the charger to the phone through the air, with no cables involved? Today, we're going to find out!

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Electromagnetic Induction

We're going to take you back to high school, but we promise it won't be boring. Electromagnetic induction was discovered almost 200 years ago by a guy called Michal Faraday back in 1831. He played with copper wires and magnets and discovered that running a voltage through one wire made strange things happen to the other wire, even though they were not connected to one another.

We now know that a moving electric charge generates a magnetic field. That's the basic principle behind this. When electrons move through the copper wire, a magnetic field is generated; that's how electromagnets work. Now, if you put another copper coil close to the first one and fine-tune its position, the number of wires, the gauge, etc., it will pick up that magnetic field, and electrons will start moving in that second coil.

This transfer of energy is a peculiar one because it doesn't require a medium. Your smartphone charger will work in the vacuum of Space. That's because the electromagnetic field is everywhere around us, even in the emptiness of the vacuum of Space.

When you do the trick with the coil and the electric charge, it will create a disturbance in this field, much like throwing a stone in a perfectly still lake. The difference is that, unlike the lake, the electromagnetic field is not a medium by itself. It's just a property of space.

What is a smartphone wireless charger?

You might have watched videos where people disassembled these chargers or even done it yourselves. Smartphone wireless chargers consist of tiny copper coils that transfer energy to a similar system inside your phone—a thin copper coil placed just under the back cover.

The two coils have to be aligned properly for the transfer of energy to happen. You might've experienced that yourself, trying to find the right sport for your phone on the charger. More sophisticated wireless chargers (the Tesla one comes to mind) have multiple coils to provide charging at every spot you place your phone on the charger.

Wireless charging standards

Transferring electricity through the air is no joke, and there must be standards telling companies how to do it safely and also allowing wireless chargers to work universally (well, almost) with all gadgets that support wireless charging.

Qi is the primary wireless standard developed by the Wireless Power Consortium (WPC) for inductive charging over distances of up to 40mm. We won't delve into the history of the standard and all the administrative and legislative stuff; the important thing to know is that this standard (pronounced chee, by the way) has gained widespread adoption by smartphone manufacturers.

Samsung, Apple, Sony, Honor, Oppo, OnePlus, Huawei, Nokia (HMD), Motorola, and Xiaomi have incorporated Qi wireless charging into their devices.

Wireless charging speed

Qi encompasses three distinct power specifications, with a primary focus on low power for charging mobile devices. Currently, various wattages are applicable, ranging from a minimum of 5W to some devices supporting 7.5W, 10W, and even up to 15W, with a later version of the standard reaching 30W.

It's worth noting that individual companies have developed proprietary technologies to achieve faster wireless charging speeds. For instance, Oppo and OnePlus offer wireless charging capabilities of up to 50W, while Honor has pushed the limits to 100W with the Honor Magic series.

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These high-speed charging options, however, require a proprietary charging stand provided by the respective company and may not be universally supported by third-party manufacturers.

What are the advantages of wireless charging?

Well, you might've already guessed the convenience part of the equation. It's easy to just drop your phone on a charging mat and forget about it. There's more to it! Here are all the benefits summarized:

  • Easy and convenient way to charge your phone without dealing with cables (sort of)
  • Preserves the USB-C port, one of the most vulnerable spots on your phone
  • You can have wireless charging in your car, integrated into your work desk, portable wireless chargers, batteries with wireless charging—it's everywhere!

What are the disadvantages of wireless charging?

There's a price to pay when you want to transfer power using the phenomenon of electromagnetic induction. Most metals are ferromagnetic and interfere with the wireless transfer of energy (the magnetic field interferes with the electrons inside and makes them move; they don't have anywhere to go, and the jiggling creates heat). And there are still cables, unless you're using a portable battery with wireless charging support. Here are the drawbacks summarized:

  • Not all phones have wireless charging
  • It's hard to keep using your phone while charging it wirelessly
  • Wireless charging is (still) slower than wired charging
  • Wireless charging is the reason we don't have metal phones anymore
  • Most wireless chargers (barring batteries) still need cables to plug into a power source

What's next for wireless charging?

The principle that Faraday found almost 200 years ago can be applied in many different scenarios. It's the principle behind the electric motors we use everywhere, from our vacuum cleaners to our Teslas (for the lucky ones of us who own one).

Inductive charging has been used to power much bigger things too. There's a bus in South Korea running over a strip of road that has charging coils in it. Nicola Tesla himself carried out strange and dangerous experiments, transferring large amounts of energy over long distances.

There are fundamental limitations when it comes to transferring power this way. If you want to do it over a long distance, you need a very strong magnetic field, and those can be dangerous to living creatures.

But the technology evolves, and one day we might have a universal wireless charging hub in our home that will be able to charge all our gadgets, no matter where they are, without frying us in the process. Fingers crossed!

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