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What Is Qi Wireless Charging?

Last updated: 3 years ago
5 min read

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Qi-wireless charging is a global standard for charging portable gadgets without a cable. It provides a convenient way of placing a smartphone or earbuds on a charging pad to slowly fill up the battery.

Reverse wireless charging

In the near future, we’ll see more and more products charge wirelessly. Some consumer electronics like smartphones, smartwatches, and headphones already support wireless charging.

And among all the types, Qi wireless charging is the most common.

Should your next headphones support it?

CONTENTS (show more)

    What is Qi Wireless Charging?

    It’s a standard for wireless charging. Wireless Power Consortium (WPC) wants to standardize the Qi wireless charging as the universal standard such as Bluetooth and USB-C.

    Qi is pronounced “chee,” and it means “life energy” in Chinese.

    It’s essential to have universal standards if you want to keep your tech safe, and most importantly, minimize customer confusion.

    Qi wireless charging standard supports both magnetic induction and resonance. Mainly to cover up all the areas of wireless charging that could be implemented in the future.

    Since many devices can charge wirelessly, manufacturers are already trying to implement Qi wireless chargers in everyday objects like tables and nightstands.

    Lately, WPC added two new wireless charging specifications: BPP (Basic Power Profile) and EPP (Extended Power Profile).

    • BPP represents the baseline for Qi chargers and can only provide a total power of 5W.
    • EPP can deliver up to 15W and more (OnePlus Warp Charge 30 can reach 30W). Besides that, EPP also requires chargers to meet higher quality standards in design, safety, and performance.

    What does that mean for charging times in reality?

    Current Charging Speeds for Qi Wireless Charging

    Let’s compare charging speeds in a real-world situation to see how much you benefit from a faster Qi charger. Nowadays, the most common wireless charging speeds range from 5W to 15W, with a small number of devices that could go even faster.

    For example, let’s take an iPhone 12 Pro Max and use a different charging speed for 30 minutes.

    • A 5W wireless charger gives you around 21% of the battery.
    • A 15W wireless charger can give you 35% of the battery.

    There are many different Qi-enabled wireless charging pads. However, manufacturers tend to limit devices to only charge at full speed when you place them on a correct pad.

    For example, iPhone 12 Pro Max supports wireless charging up to 15W but can only achieve that speed with Apple’s proprietary MagSafe charger. Otherwise, the speed drops to 7.5W.

    Therefore, you need to buy a dedicated charging pad if you want to charge at full speeds.

    Wireless charging devices
    If your phone or headphones support wireless charging, they also support Qi standard.

    How Does Wireless Charging Work?

    Even though the technology gained public interest only a few years ago, Nikola Tesla first showed how to transfer electricity wirelessly with his Tesla Coil. Of course, modern wireless charging is a completely different technology.

    Magnetic Induction

    In practice, when you have a copper coil and run through an electric current (AC), it creates an electromagnetic field. When you place two coils opposite each other, the transmitting one with the current transfers energy to the receiving one without current. That is called magnetic induction.

    The magnetic energy is then stabilized and converted into electric energy (DC) so that it can power up your device’s battery. The main problem with magnetic inductive charging is that two coils need to be very close to each other.

    Wireless charging mat
    Your device needs to support transmitter specifications you want wireless charging to work.

    Magnetic Resonance

    Manufacturers had to resort to magnetic resonance to ensure your device can charge over “longer” distances. Using resonant frequency, you can charge your device up to 1.8 inches (4.5 centimeters) away.

    Both the power transmitter and the power receiver need to work on the same magnetic resonant frequency to recognize each other. Otherwise, the receiving device can’t initiate the charging process.

    Are There Any Other Wireless Charging Standards?

    Qi standard is one of 3 wireless charging standards. However, Qi is the most widespread and compatible with all popular devices on the market.

    • The second standard is the PMA. It’s a product of Power Matters Alliance, and it uses magnetic induction to transmit energy. Even though both Qi and PMA use the same technology, they’re not compatible. Only Samsung smartphones support both standards. The rest of the market works solely on Qi.
    • The third one is A4WP (Alliance For Wireless Power). They based their solution on magnetic resonance, and in theory, it could power up to 8 devices at the time with 50W power within a 2-inch (5 centimeters) radius. In the year 2015, they merged with PMA to form AirFuel Alliance.

    Why Are Standards Important?

    Much like wired charging, different chips and sensors need to communicate with each other to prevent malfunctions. Standards are used for synchronized communication between transmitting and receiving devices. Otherwise, things can get out of control:

    • Your device might overheat. Wireless charging efficiency is only around 60%, which means that the rest of the energy needs to disperse into thin air, usually in the form of heat. That’s why the most powerful chargers come with fans to keep the pad from melting.
    • The device might get overload with energy. For example, your pad can fast-charge up to 20W, but your wireless earbuds only support 5W. Without standards, the pad can’t recognize the coil in the receiving device, so it charges at full power. It results in a fried-up coil inside the earbud’s case.

    There are also proprietary certifications that allow a specific charger to charge at full speed. For example, Samsung requires third-party chargers to pass the Samsung Proprietary Power Delivery Extension. Otherwise, these chargers only work at 5W.

    Wireless Charging In Headphones

    With wireless charging gaining traction within the smartphone industry, there is no telling when Bluetooth headphones finally ditch the charging port. It’s no secret that Apple wants to go port-less, affecting all wireless gadgets, even headphones.

    Many true wireless earbuds have a wireless charging coil built inside the charging case. Many smartphones also support invert charging, where a phone can wirelessly charge earbuds.

    Skullcandy Push Ultra charging port
    That lightning logo shows the location of the integrated wireless charging coil.

    Even full-sized headphones are slowly receiving support for wireless charging. One of them are Marshall Major IV on-ear headphones, with the coil built inside the earcup.

    However, the list of headphones that support Qi charging is short. You will probably have to wait a couple more years before wireless charging in headphones becomes widespread.

    What Is The Future Of Wireless Charging?

    While it’s practical to charge your mobile device or earbuds by plugging the cable, wireless charging technology still needs improvements. Having to place something on a specific spot eliminates the point of something being completely wireless.

    There is also a problem with efficiency. Around 40% of power is dispersed into the environment in the form of heat. That means you burn off more electricity to charge a device wirelessly rather than using a wired connection.

    However, there are possible solutions to both problems.

    Pi Charger

    This was a neat solution and a step towards a world where you don’t have to place your device on a specific spot. In the case of Pi Charger, the idea was to leave a device somewhere in the Charger’s vicinity. The latter would recognize the device’s location and beam a magnetic resonant frequency in its direction.

    Pi Charger wireless charger
    The Qi-compatible wireless charging system uses object detection and created a magnetic field that charges up phones around it.

    However, for Charger to recognize the device, it would need to carry a special case. Which is something test users didn’t want. They also complained about the base station size.

    Even though the team behind Pi promised that the future Charger won’t require a special case, therefore allowing all devices that support the Qi standard to charge wirelessly, the project flopped. While the MIT-founded company renamed to Spansive, they’re still working on making wireless charging truly wireless.

    Charging via laser beam

    Using lasers for wireless charging sounds very futuristic. The laser itself is a form of concentrated energy, and it can be used to power up devices at longer distances.

    Engineers at the University of Washington have designed a safe way to charge up a device by using a laser. It could reach a distance of 14 feet (4.3 meters), with a power transfer equal to a wired USB connection.

    While the distance is extendable, lasers pose one big problem: obstacles. In practice, if the laser doesn’t have a clear line of sight on the device, it can’t charge it.

    Common Use of Qi Technology

    You can find them among the best workout headphones. You probably go to the gym regularly and need your buds ready to go. Qi charging makes it easy.

    But otherwise, all modern true wireless earbuds will eventually support it. It’s in the future and it’s becoming more convenient.