December 19, 2016
How Does Wireless Charging Work?
At mophie we are no strangers to wireless charging. Newer to the smartphone scene, wireless charging technology allows you to easily charge your phone or device without using any cables. Whether you are on the go or simply tired of fussing with cables, wireless charging is a great alternative. A newer technology, wireless charging can seem a little complex at first so we’re breaking it down for you from A to Z.
What is wireless charging?
Wireless charging, or wireless inductive charging, is the process through which the batteries in an electronic device are recharged through an electromagnetic induction current. Although wireless charging appears to be a new technology because of its broadening application in modern personal electronic devices, most notably smartphones, the principles of wireless charging were demonstrated over a century ago by Nikola Tesla. Prior to the turn of the twentieth century, Tesla was able to use wireless inductive charging to power light bulbs that were placed a short distance away from an array of coils connected to a power source that generated an electromagnetic field. Although Tesla was unable to successfully translate this technology into a commercial product at the time, the legacy of his work can be seen today in wireless charging products.
Wireless charging is a technology that many of us have already used, perhaps without realizing it. For the past two decades, wireless charging has been used to power electric toothbrushes, razors, and household wireless phones. These products utilized a charging dock that the toothbrush or phone was set on to charge after use. This dock then charged the item through wireless inductive charging. For items such as toothbrushes and electric razors, this type of charging is safer due to the ability to function safely in a wet environment. Traditional charging through a cable in an application that may come into contact with water is inherently unsafe. If the charging cable is wet when plugged into the device it could either shock the user, or damage the product.
Wireless household phones, on the other hand, used the technology as a means to keep the phone fully charged while offering the convenience to pick up and use the phone without having to disconnect a charging cable. Both of these time tested applications have proven that wireless inductive charging can be beneficial and convenient to the end user in a variety of circumstances. Additionally, the relatively long history of wireless charging demonstrates that this technology can be safely utilized in an increasingly broad range of both personal and commercial electronics.
How does wireless charging work?
The typical phone charger takes the 220-volt Alternating Current (AC) coming in from your house and converts it to Direct Current (DC), which is needed to charge your device. First your phone charger steps down the 220v input current into a more appropriate current through the use of a transformer, which are a series of copper coils. This stepped down AC current is then converted into DC signal using a process called rectification. The rectified, but still oscillating, DC signal is then filtered and regulated to produce a stream of DC signal that has a minimal level of fluctuations. This regulated current is then passed to your device at a strength usually around 5v or 2v, depending on your charging station.
Wireless charging uses the same principles as direct charging. The high frequency 220v AC current coming from your house needs to be stepped down and converted to DC to power your device. However, it requires this process be accomplished over a spatial distance without the use of a cord between the power supply and device. To do this, wireless chargers utilize two separate coils to produce an electromagnetic field. One of these coils accepts the 220v AC current from your house and resides in the charging bay or dock of your charger. The AC current enters the device and is transmitted to the coil in the charging station through a transmitter circuit.
However, without a second coil present, no electromagnetic field is being created at this point. In wireless charging devices, the second coil is either embedded in the end user’s device (such as in their smartphone), or is embedded in an eternal battery pack case that encloses their device. Once the user places their smartphone onto or within range of the charging station, the current from the first coil within the charging station is transmitted to the second coil in the receiving device. The current passing through these two coils generates an electromagnetic field. The byproduct of this electromagnetic field is the generation of an electrical current in the receiving device. This generated current is then converted by a circuit located in the receiving device into a usable DC signal. Once this has been accomplished, the battery in your electronic device begins to charge.
Wireless chargers function by creating an electromagnetic field through two coils in close proximity. One coil is in the charging dock or pad; the other coil is typically in or attached to your phone or device. Once the electromagnetic field is created it then generates AC signal in the receiving device, which is then converted to DC signal and begins charging your battery.
Benefits of Wireless Charging
The main benefit of wireless charging is that it offers unparalleled convenience when compared to direct charging. Let’s take smartphones as an example. With wireless charging you can set your phone on the charging station and it begins charging. If you receive a phone call or text message, you can pick up your phone and use it or walk around with it, then return it to the charging station without having to plug in or unplug a cable each time. Or if you are like many and use your phone as an alarm clock but charge it overnight, once your alarm goes off you can easily and conveniently grab your phone and disable your alarm without having to fumble with the charging cable in the dark.
The second major benefit of wireless charging stations is they eliminate every cable except the one that runs from the charging station to your wall socket. Let’s face it, charging cables are a messy annoyance that many of us would gladly get rid of. Charging cables also potentially create fire hazards. This is particularly true near the end of a cable, where it is repeatedly bent when inserting it into a device. These bends can fray the insulation surrounding the cables, which can lead to arcing of current between cables and result in frayed or burned insulation. These weaknesses in cables can also lead to shock risks, which many of us can attest to first hand.
A third major benefit, related to both convenience and eliminating cables, is wireless charging stations offer the ability to charge multiple devices. While traditional charging docks can also do this, what you are left with is a mess of cables leading to each device being charged. Typically, users leave multiple cables in the charging dock for convenience, which results in a confusion of cables around the dock. With wireless charging stations, multiple devices or phones can be placed onto the dock and charge simultaneously with none of the mess of a standard charging station. Users can also quickly retrieve their device if they need to make a call or respond to a text message without disturbing the charging of another device.
One of the final major benefits of wireless charging is that you, as the consumer, can expect to see more wireless charging hubs popping up in major businesses, airports, and libraries in the near future. Businesses, such as Starbucks, have begun rolling out wireless charging stations to select stores, with the intention of expanding them within the near future. Because of the convenience that wireless charging offers, the availability of wireless charging stations is anticipated to replace that of standard charging docks within the near future. For people that travel often, wireless charging ensures that you will never have to worry about forgetting to pack your charging cable in order to keep your phone charged and ready to go.
Technology forecasters anticipate that wireless charging will continue to become more ubiquitous in our rapidly evolving electronics landscape. As devices continue to be upgraded and improved, increasing numbers of manufacturers will be incorporating wireless charging into the device itself.
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