Smartphone wireless charging is one of the best technologies developed in the last few years - the ability to charge your phone simply by placing it on a stand is a fantastic piece of modern convenience. But how exactly does this magic work? In this article we’ll be looking at the technology behind wireless charging, and why it allows you to finally ditch your iPhone cable.
When we talk about wireless charging, we’re really talking about ‘inductive charging’. This is a method of charging that uses electromagnetism to induce power into a device without the need for a physical connection. If the name sounds familiar, that’s because induction charging is used in several other home technologies - it’s most commonly seen with induction hobs on modern cookers.
The basic theory of induction charging started with Michael Faraday in 1931, when he discovered 2 important pieces of information:
Passing a current through a wire close to a magnet generates a fluctuating magnetic field.
Rotating a wire through a magnetic field generates an electric current.
These two concepts work together to form the basis of electromagnetic induction. A current is fed through a wire wrapped around a magnet, which generates a magnetic field that causes a current to appear in a second, nearby wire.
While induction cooking uses this current to quick generate heat in cast iron pots, induction charging has other plans for the current: it is transformed from Alternating Current (AC) into Direct Current (DC) using a device called a rectifier and fed into the battery of the device.
This is what happens when you place your iPhone on a charging mat - an electromagnetic field is generated from the mat, which intersects with the phone. The inductive charging generates alternating current in an induction coil inside the phone, which is converted into direct current and used to power the phone or fed into the battery. Clever stuff indeed!
How does Wireless Charging Work?
Benefits & Limitations of Wireless Charging
While induction charging may seem like magic, it’s worth looking closely at the benefits and limitations of the technology:
Instant start/stop charging
No chance for loose cables to get caught or cause an accident
Slower than wire charging
Requires a special charging surface
Not all smartphones are compatible with wireless charging
Phone must keep in contact with charging surface
A lot of the benefits of wireless charging lies in the ease & convenience, but the trade-off is slower charging and the need for special/compatible equipment. There is also the strange state that wireless charging can be simultaneously less and more restrictive than standard cable charging.
On the one hand, you don’t have to hunt under your desk for an elusive USB cable to plug into your phone. On the other hand, the phone must be kept in contact with the charging surface to enable charging. Therefore you lose the ability to pick your phone off the desk and use it while charging continues - although this is mitigated by the fact that charging instantly restarts the moment you place the phone back onto the charger again.
We’ve mentioned that charging speeds are slower than standard cable charging, but the actual speed depends largely on the hardware you’re using. Wireless chargers are measured in watts (W) - with higher watts enabling better power transfer, and therefore faster charging. The first wave of wireless chargers were very slow - they only allowed a single watt, meaning extremely slow charging times. Since then, the technology has improved considerably - wireless chargers can now charge up to 15W on compatible phones! This means significantly faster charging - almost as fast as cable charging in some cases.
The Truth About Wireless Charging
Compatibility & Available Models
If you’re interested in using wireless charging, the first port of call is to make sure that your phone is compatible with the technology. Luckily the vast majority of new & recent phones support wireless charging. For those that don’t, it’s possible to buy a phone case that works as a wireless charger, feeding the power into the battery. These cases can be expensive and bulky, but are a good solution if you don’t want to upgrade your phone.
With regards to cases - it’s important to note that some cases will block or reduce wireless charging, so make sure to double-check the case is marked as designed for wireless charging.
Finally, even if your phone supports wireless charging, it’s wise to check exactly what wireless charging it supports. While wireless chargers can deliver up to 15W of power, not all phones will draw that much. Some phones - such as previous model iPhones - are limited to only a 5W power draw, no matter the charging surface you use.
When looking for wireless chargers, you have a couple of different styles:
Stand: An upright stand that functions like a normal phone stand - allows you to view your phone while it charges
Mat: A circular mat you place your phone onto. A simple and stylish design that doesn’t take up much space
Multi-device: Some companies make special chargers that are designed to charge multiple devices at once. Some look like large charging mats, some are trees, some even have radios or clocks built into them! You’ll be paying more, but they are potentially far more useful.
For Kagoo’s recommendation, Belkin are well known for their high-quality products. In fact, I’m using one of their mats to charge my phone as I write this. They also have a stand version which does the job very well.
It’s not just phones that can benefit from wireless charging - some models of headphones and watches offer wireless charging capabilities. Apple’s Airpod headphones offer a wireless charging case - meaning you can just throw it onto a charging surface, and it’ll juice up your headphones! With watches, you will normally have to buy a specific charger, since many use proprietary charging methods. So unfortunately a Galaxy Watch charger won’t work with an Apple Watch. So make sure to double-check the compatibility on any charger you buy
The Future of Wireless Charging
At the moment wireless charging is really starting to become a mainstream tech, but there is far further it could go in the future. Far more devices could gain wireless charging capabilities - watches, mice, laptops, and the infrastructure could expand far beyond your personal charging mat. Some coffee shops have experimented with installing charging pads into the tables, meaning that anyone can charge their phone while they drink - such public infrastructure could make wireless charging an everyday convenience. Add in greatly increased charging speeds, and it becomes a future where running out of power is a thing of the past.
However an even more interesting technology is on the horizon - true wireless ‘air’ charging. This technology - which has existed in R&D labs for the last few years - would allow a device to charge your phone over the air, with no need for wires at all. The power is beamed to your phone just like a wi-fi signal, meaning constant charge the minute you walk into a room! Now doesn’t that sound space-age! Exciting times indeed!