Also called inductive charging, wireless charging or wireless power transfer is a technique to charge battery-powered electronics without a physical connection (almost). There are no physical cables and connectors in the mix, which results in a much tidier and convenient charging environment. However, not all devices compatible with wireless charging have the capability built into the device. For instance, some smartphones need a special attachment such as a back cover or sleeve with charging contact points to enable their wireless charging capabilities. Usually, the charging cover is specific to the device and cannot be attached to all devices in the category.

A compatible wireless charger, a device that can wirelessly charge itself, a wall outlet, and a charger for the wireless charging equipment are required for wireless charging to work. This means wireless charging is not truly wireless. There’s still the need to plug the charger in a wall socket. However, the phrase “wireless charging” is used because there’s no wire between the device (such as a phone) and charger. With traditional charging, that’s not the case. Such wireless energy transfer is similar to how cellular phones, Wi-Fi, radio, and television signals work. 

History

Wireless charging isn’t completely new. In fact, inductive charging technologies have powered up electric toothbrushes in the past for several years. Going back even further, several million volts of electricity were wirelessly transmitted by Nikola Tesla in 1899 to power 200 bulbs and an electric motor. However, things didn’t grabbed pace much back then since the technologies used by Nikola Tesla were conflicting technologies. Also, the electronics and wires weren’t small enough to render the charging technique practical.

Wireless charging for handheld devices first came to the scene in the form of Touchstone, a proprietary charging standard for the Palm Pre. The standard was later adopted by other vendors. In fact, when Palm was getting ready to present the Touchstone at Consumer Electronics Show (CES) 2009, a small unit comprising manufacturers Logitech, Sanyo, Philips, and Texas Instruments came together in December 2008 to create the Wireless Power Consortium (WPC). WPC came up with the first variant of Qi charging, Qi 1.0, in 2009. In the subsequent months, several big names joined the consortium, including Motorola, LG, HTC, Sony, Nokia, and Samsung, making Qi much stronger and more relevant.  

Charging Mechanism

The wireless power is transferred via electromagnetic induction. This means the device receives power not via a standard cable but wirelessly instead through electromagnetic fields. The base station or the charging pad comprises coils of wire that develop a magnetic field when current passes through the station. This magnetic field could transfer electrical current to another set of coiled wire without any direct physical contact. When the other coil of wire is a component of a circuit that charges batteries, then such interaction between the two coils of wire results in wireless charging.

Usually, the device to be charged is placed on the wireless charger, which is usually a charging pad. The charging pad should have been connected to the wall socket through a charging device. The charging station sends power and the mobile device receives the energy. The charging base activates and transmits energy only when a device is placed on the pad. Moreover, if the battery is completely charged, the charging enters standby mode. By the way, even if the charging pad is large enough to accommodate more than one device at a time, wirelessly charging multiple devices simultaneously is not possible.

The wireless charging pad or station charges devices that are meant to be charged and doesn’t transfer power to anything that’s placed on it. This is possible because the tiny transmitters in the charging pad communicate or interact with only those devices that have small receivers within. In case the device at the receiving end doesn’t comprise those receivers, the charging pad won’t transfer power. This interaction between transmitters and receivers is the reason why the charging process stops automatically when the device is fully charged.

Electric toothbrushes need to be docked for charging. This may make you believe the brush is physically connected to the power station, but it’s not. The docking is only to ensure the brush stands in place throughout the charging process. With wired charging, the wet toothbrush would become highly susceptible to electrical shock.

Charging Standards

There is no single wireless charging standard. There are three of them: Qi, Powermat, and Rezence. And these are presented by three different organizations. Qi is courtesy Wireless Power Consortium (WPC); Powermat is a standard created by Power Matters Alliance (PMA); and Rezence is the latest entrant, thanks to Alliance for Wireless Power (A4WP).

Needless to mention, a Qi-enabled device won’t charge on a Powermat charging pad, since both are incompatible, or the signals received and sent by the two are different. Similar is the case with Rezence as well. However, there could be exceptions to this rule. For instance, Samsung Galaxy smartphones can wirelessly charge both on a Powermat and Qi power station.

All the three charging standards are approaching the market differently. Qi has been trying hard to get as many manufacturers on-board, which it has been doing quite successfully, since it’s the most popular wireless charging standard within the mobile devices realm. PMA, on the other hand, is not resorting to push strategy. It, in fact, is adopting a pull strategy to brand Powermat and trying to create a brand for itself by partnering with certain brands.

For instance, PMA partnered with Starbucks to launch a PMA charger test in several Starbucks’ stores. When compared to Qi and PMA, A4WP is trailing well behind as far as the rate of adoption is concerned. However, it’s still not out of the race. It, in fact, joined hands with Intel, lending itself some much needed credibility and enhanced resources. PMA and A4WP thereafter merged in 2015 to form the AirFuel Alliance.

Limitations

Most people know wireless charging exists. But the majority have still not made the switch to the same from traditional charging methods. And the major reason being the charging speed and efficiency, along with the lack of a universal charging standard.

Compared to wired charging, wireless charging speeds are considerably slower, and also not as efficient. In fact, when a device needs to be powered up from scratch, a wired connection tends to be the more plausible charging method. Moreover, with faster charging technologies entering the world of wired charging, things have headed further south for the wireless charging clan.

Most smartphone manufacturers, especially Android device makers, have taken a non-wireless charging route. The reason being the onset of the USB-C port. USB-C offers quicker charging capabilities than wireless, lets devices get thinner, and is reversible, making it slightly more convenient compared to microUSB. As aforementioned, there are different wireless charging standards, and this lack of a universal charging standard is creating confusion among consumers and making them reluctant to take the plunge and ditch their microUSBs for good. Though there have been modules developed to work with both PMA and Qi, there’s still not a lot of buzz happening there.

Future

Wireless charging is not out of the picture yet. However, it needs to do a lot of catching up in terms of speed and efficiency, and also make the charging technology truly “wireless”. Wireless technology is primarily identified with smartphones, wearables (smartwatches) and similar mobile devices. To truly become popular, wireless charging technology must lend support to a range of other devices or equipment such as electric cars, and medical equipment and industrial tools that are largely powered through mains power supplies or battery packs.

Electric cars, on a single charge, can travel only a certain distance. Charging the car requires charging cables, charging point, and also significant waiting period. Wireless charging can potentially make the charging experience seamless, especially when it’s possible to charge the vehicle when parked or moving. Charging pads can be built into parking spots, for instance.   

Such futuristic technologies are fortunately in the pipeline. In fact, South Korean electric buses (as of 2013) can be charged via a wireless platform. Mercedes and Audi, at CES 2016, discussed wireless charging capabilities for cars. There are furniture being made, such as tables and lamps, with inbuilt charging stations. These are just a few examples. In the coming days, wireless charging would become a lot more versatile and accessible.

Moreover, WPC and AirFuel Alliance aren’t the only groups working hard to create wireless charging tools and solutions. There are several other smaller organizations that are chiming in with their offerings too. Humavox, an Israeli startup, has developed its own wireless charging solution for consumer electronics, hearables, weareables, etc. Then there’s Energous, a firm that’s also working with radio wave-based technology.