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Wireless Charging: How it Works

Wireless Charging: How it Works

A brief history

The process that makes modern wireless charging possible isn’t exactly new. In the 1800’s, scientist Michael Faraday experimented with the idea of transmitting a current through the air after his discovery of electromagnetic conduction, which can be achieved when an electromagnetic field is created between two conductors that act like a transmitter and a receiver. This principle was later worked upon by Nikola Tesla in a process called resonant inductive coupling, which he used to power a light bulb in his laboratory. A few years later he patented the famous Tesla coil.

Whilst the discoveries these scientists made were marvels of their day, there wasn’t a whole lot of practical application this type of electrical transmission could be used for. Even throughout the twentieth century, wireless charging had very few applications it could be used for. A lot of this has to do with the efficiency of wireless charging and the power demands of appliances.

Modern day use

These days, in a world of handheld devices and gadgets powered by lithium batteries, wireless charging becomes more useful. Modern wireless charging pads work in much the same way as the original process, in that there is an electromagnetic copper coil in the base, which links up with a smaller coil in the back of your phone, transferring power via the electromagnetic field created. These two coils act like transmitter and receiver as mentioned above.

However, this type of charging isn’t without its drawbacks. When a smartphone is placed on a wireless charging pad, it must be in full contact with the charging pad for the highest charging efficiency, but there is always some energy loss. If you hold the phone a few centimeters above the pad, the phone can still receive a little bit of energy. If you hold it 10 centimeters above the pad, it probably receives nothing. This could be alleviated by simply making a larger electromagnetic coil, but it would be using a lot of power and more of that would be wasted as well. A good analogy would be to imagine a wet coat hung above a hot radiator to dry. The wet coat will of course absorb heat rising up from the radiator, but it won’t absorb all of it. If you moved the coat to hang above a larger radiator, much more heat is given off, but the coat probably isn’t absorbing much more than it was above the smaller radiator, and hence a lot more energy is lost.

It’s estimated in 2021, that if the billions of smartphones in use today all switched to wireless charging, the net energy waste would be enough to power at least 35,000 homes.

What are the pros of wireless charging?

The ease of simply placing your phone down on a charging pad and picking it up whenever needed, knowing the whole time it’s charging when it’s down, is sort of like a ‘set it and forget it’ convenience. It really doesn’t even matter that wireless charging is slower than wired, because the point is that it is charging whenever it is not in your hand. Unlike with a cable where you would be plugging it in and out all the time.

Modern furniture makers are even making desks and table tops with wireless charging pads embedded into the surface of the unit. This is in addition aided by the industry standard of wireless charging know as ‘Qi’ (chee). Seeing as virtually all devices intended for wireless charging are built to be compatible with Qi, any device that’s capable of wireless charging can be used with almost any charging pad. And with charging pads built into furniture surfaces, it eliminates cables for an even sleeker, tidier look.

In the United States, Starbucks have gone as far as to integrate thousands of wireless charging pads into their coffee shop tables. And we can expect this to become even more widespread over the next few years.

So will wireless chargers replace the ubiquitous charging cable any time soon? Likely not. Although they will become more widespread, wireless charging of portable devices is still fairly niche and it seems the efficiency and functionality of electricity delivered by cable is a tough one to beat. However, as wireless charging technology improves and things like wireless charging over distance is explored further, it certainly seems like something most of us will be using at some point in the coming years. But don’t get carried away, the thought of high-speed wireless charging from the other side of a room is a way off yet, and so… we’re gonna be stuck with the wireless charging pad (with wire) for some time to come.

Use in other industries

Wireless charging is not only for smartphones, it’s making an impact in other areas too — such as the medical field — where there is a huge potential for this type of technology to be used for charging or powering implants. In addition, the technology is also making inroads into anything from warehouse robots to tiny IoT (Internet of Things).

Electric cars stand to gain immensely from wireless charging technology, whereby a car simply parks over a charging station built into the ground and charging starts automatically when the car pulls up. An even more futuristic idea is that there will be wireless charging lanes we drive in, and the vehicle doesn’t even need to stop to charge its batteries as it is being charged while driven. A 1:87 scale model of a city in a Saint Petersburg museum — Grand Maket Rossiya — even has its miniature vehicles powered in this way, which is thought to be the first time such technology has been used for this purpose.

In the future, charging will become less of a conscious thing, in that it will be an automatic or ‘always-on’ process that begins when we arrive home or get to the office.

Types of wireless chargers for smartphones

Satechi Trio Wireless Charging Pad -- $119.99

What type of wireless chargers are there and how much do they cost? For the smartphone market, it could be said that there 3 different main types. The first and most common is the round charging pad. This just sits on your desk or table and you place the back of your back on the center of it. The second type, sometimes called a station, is like a stand, and the phone sits-up at an angle. This is useful if you are frequently needing to check notifications or making video calls and such. The third, and least common type is like a bowl or basket that you simply place your phone or smartwatch in. This is useful if you have multiple devices that support wireless charging.

Prices typically vary from about $15 for a wireless charging pad and up to $80 for a wireless charging station, depending on the brand and functions. Click here to see the latest wireless charging offerings on Amazon.

That’s it for now. Be sure to check back at the Kovol Blog for future articles and guides.

Thank you and stay safe!

The Kovol Blog Team

 

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