Wireless Charging: Where We’re At Today

How does wireless charging work?

Wireless charging transfers energy from the docking station to the battery using an electromagnetic field — the same phenomenon that causes a toy magnet to move a paper clip without touching it (another transfer of energy).

Charging stations convert a power source's voltage to high frequency alternating current (AC) and fires it off to the transmitter coil. This coil of wires directs the energy outward as an electromagnetic field when the phone is close enough to receive it. Devices compatible with wireless charging have a similar receiver coil that receives this field's energy, convert it to direct current (DC), and uses the power to charge the battery. Energy safely moves between these two points—there are no arcs of electricity or sparks to worry about here!

Varying Methods and Standards

As with many new technologies, there are a few different approaches with wireless charging. A number of companies engineered their own standards for wireless power transfer. As of 2017, the two biggest players in the game emerged as Wireless Power Consortium's Qi (pronounced "chee") and AirFuel Alliance (commonly known by its pre-merger name PMA). While both of these systems use a nearly identical inductive charging design, they employ different transmission frequencies and connection standards with devices when communicating and controlling power management.

So what does this mean for the smartphone industry? For the time being, Qi is integrated in both Apple and Samsung's flagship products, leading the way as the most popular system in consumer electronics. However, external wireless charging receivers often use the PMA standard. Luckily, there are charging stations designed to accommodate each of these standards, and many can support both.

How do you use a wireless charger?

While it's called "wireless charging" most charging stations must be plugged in to a power source before it can begin to generate electricity. Portable power banks, however, can charge your device without simultaneously being plugged in. Once the charger is receiving power, there's usually only one step left: put your phone on it. Simply place the device screen-side-up onto the circular pad. Magnets in the charging station will “grab” the phone and put it in the precise position. You may need to take any protective casing off depending on the handset model and the thickness of the material, but most often this is not required. If it's working, the normal charging indicator light will turn on.

That's it? Yes! Using wireless charging is much easier than understanding how it works. However, there are a few reasons why powering your handset with an inductive charger might not work.

• Something may be between the phone and the charger. The power station uses magnets to center the device on the correct point. Remove thick cases or any obstructing object and allow this magnetic connection to "center" the phone on the right spot. Device attachments that use magnets are more likely to interfere with this.
• The phone is attempting to charge from a cable. Devices are not made to receive power from two sources at once (yet). Your phone will start charging once the charging cable is removed.
• It's getting too hot! Smartphones will stop charging if the battery exceeds a certain temperature. Wireless charging creates some heat during the process that can add to the temperature of a phone that’s heavily used or left out in the sun.
• The handset vibrated, causing it to move off of the charging station. This is rare, since the magnets are usually strong enough to keep it centered.

Most newer flagship phones and smartwatches now come with Qi or PMA receivers. If your phone does not include a receiver, you may be able to modify your device with variety of cases and adapters that enable wireless charging. These add-ons make supported devices compatible with Qi, PMA, or both systems, depending on the unit. There are thousands of accessories of varying performance and quality, so it would behoove you to read reviews and scour the specifications before making a purchase.

How does wireless charging compared to wired charging?

Speed

How fast can you wirelessly charge your smartphone? The answer is complicated. Just as there's a "fast/quick/turbo/rapid charging" feature, there's also a version for inductive charging. However, like the conventional wire process that utilizes special cords and adapters, fast wireless charging requires a compatible phone and charger, both operating on the same protocol. Standard cordless charging stations feature a 7.5 to 10 watt transfer rate while the new models go up to 15W.

Since wireless charging technology is still relatively new, it can be hard to find a setup that supports fast inductive charging. The best way to ensure that it will work is to use first party or other manufacturer recommended products. Use Google to search if your phone and the charging accessory are compatible with the 15W process.

Public Use

With the advent of wireless charging, it's much easier for public places like restaurants and stores to provide power for patrons' devices. Instead of using cords that look cluttered, could easily be broken or stolen, businesses can feature tables with integrated power stations. Users only need to set their phone down for service.

Companies like Starbucks have already begun taking advantage of this new opportunity. The coffee giant added wireless chargers to its stores in 2015 that were only compatible with the PMA standard. After the iPhone 8, 8 Plus, and X were announced in 2017 to be Qi compatible only, Starbucks asked the company that made the charging station to update their docks for the new popular standard. When one of the most popular coffeehouses in the world gets on board, it’s a safe bet that it’s only a matter of time before wireless charging is a universally adopted technology.