Wireless Charging Technology – How It Works?

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Wireless charging technology entered the market in 2009. This November, Starbucks started its plan to add wireless charging stations in their stores, adding Powermat wireless chargers in 200 of their San Francisco area cafes. Despite the support, the general public seems reluctant to adapt the new technology, preferring the reassurance of a plugged in device. But as bigger and more powerful phones and tablets continue to flood the market, keeping those electronics charged has become an issue. Wireless charging could be the future of high tech gadgetry, rendering useless the need to carry backup batteries and tangled wires. Consumers are still left wondering, how does it work?

How it Works

At its simplest, wireless charging transports an electrical current from a powered transmitter to a device without being physically connected. This is done through inductive coupling, also known as magnetic resonance, where the charging station transmits electricity by way of a transmitter coil.

Magnetic energy is entirely safe to send through the air where as normal electric currents would send dangerous and unwieldy bolts of electricity to the adjacent device. This technology was originally invented back in 1831 by Michael Faraday when he used a transmitter coil to send power over to an adjacent coil. This technology was again tested in the market back in 1990 to design a safe charging station for an electric toothbrush. With the simplicity of cellphones and other electronic devices at the time, nobody needed to conveniently charge batteries that were already lasting for days. Today’s phones, however, are more like small computers, and their processing power is quickly outranging battery capacities. Keeping a charge has become an issue.

From Outlet to Phone

How does energy get from a pad into a phone? First, the wireless charging pad converts its voltage into a high frequency alternating current. This current is then prepped for its voyage by a circuit that converts the power into waves of energy with the help of the transmitter coil. A device located in this range with a receiving coil picks up the signal and then the magnetic energy is transformed back into voltage, powering the device.

The waves broadcast by the charging station are high energy but have a very short range. By creating bigger transmitter coils, the signal can travel farther. It can also be extended if two devices resonate with the same frequency. Within this range, they have the power to move through most materials, whether it be a table cloth, wooden desk or granite countertop. They are, however, entirely stopped by metal.

The Future

Modern wireless charging technology still uses this basic principle with the receiving devices having a built in receiver coil. Systems like the Powermat consist of an adapter that plugs into your phone, giving it an external receiving ring. This is lined up with the ring on the mat, providing the charge. Starbucks loans this out to patrons and has adapters available for purchase. These come in two models—iPhone and USB adapter. The newest models use a very fine, built-in coil which broadcasts quicker, higher energy signals. These signals are strong enough to penetrate through a phone’s case or a tablet protective cover.

Without any actual electronic connections being made, there is less corrosion on connecting systems and less wear and tear on connecting ports. Electronic devices that might have been dangerous to charge in wet or dirty environments become safe. In the long run, devices become cheaper if only because owners never have to repurchase lost cords or extra batteries. The advantages of wireless charging come at a price, though. Energy broadcast by the wireless station is not all absorbed and much of it is lost. This also means slower charging than a direct connection. 2014 marks a huge rise in wireless charging devices. Most phones constructed in 2015 will house a wireless charging receiver.


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