How Wireless Charging Really Works

Have you ever put your phone on a charging pad that charges it wirelessly—no cords, no plugging in, just place it and it charges? At first it does indeed look like magic, but what is really happening there? While wireless charging may seem very modern and futuristic, it is based on principles we’ve known for over a century. It’s only now that the technology has caught up to make it a practical everyday feature for us.

Let’s go over it in a simple, non-technical way to help you see what is really going on when your phone begins to charge wirelessly.

The Basic Principle: Magnetic Induction and Transformers.

At the base of wireless charging is a principle which we now know as electromagnetic induction. This isn’t a modern discovery. The principle we use for wireless charging was first demonstrated by scientist Michael Faraday over 150 years ago. He also discovered that passing electricity through a coil of wire creates a magnetic field. And when another set of coils is placed within that magnetic field, it can capture the energy and convert it back into electricity.

This principle forms the foundation of wireless charging.

In a wireless charging system, there are two main coils:

1. Transmitting coil in the charging pad.
2. In your phone or device, which is the receiver coil.

As soon as you place your device on the charging pad, the transmitter coil puts out a magnetic field. In your phone is a receiver coil which in turn picks up that magnetic energy and converts it into electrical energy to charge your battery.

Inside the Charging Pad

When you connect your wireless charging base to a power source, it starts to produce alternating current (AC). That current runs through the transmitter coil which in turn produces an oscillating magnetic field. It’s not a random field; it’s controlled and emitted at a precise frequency.

This magnetic field covers only a small area, which in turn means your phone has to be placed precisely on the pad—put it too far off and the coils will not align well enough to produce efficient energy transfer.

This is what we call near-field inductive charging, which is the method that most phones use today.

Inside Your Phone

Your phone has a receiver coil that is inbuilt, which is usually at the back. As you place the phone on the charging pad, this coil aligns with the transmitter coil.

The magnetic field emitted by the pad induces an electric current in the receiver coil. That induced current is then changed from alternating current (AC) to direct current (DC), which is what your battery uses for charging.

All this is done in silence and at very high speed. No sparks, no heat (in ideal cases), and no wires.

The Role of the Qi Standard

In the case of wireless charging which works across multiple brands, the reason is that we have a common standard called Qi (pronounced “chee”). This standard serves as a common reference and defines how devices should play along with each other during the charge.

Thanks to Qi, your Samsung phone can charge on an Apple charging pad, or a Google device can use a third-party wireless charger. Qi also ensures:

• Safe energy transfer
• Device recognition
• Power management
• Temperature control

Without that which makes them compatible, we would have a mess of different wireless charging standards and inconsistent performance.

Why You Need Close Contact

A common question is: If we are going totally wireless, why do I have to put my phone right on the pad?

The answer is efficiency.

Unlike technologies like Wi-Fi and Bluetooth, which can operate over long distances, wireless charging works only over very short ranges. With most consumer devices, magnetic induction used in wireless charging is a very short range. For effective charge transfer, the coils in most cases have to be within a few millimeters of each other.

If the phone is out of alignment or raised too high above the pad, charge drops off—which is what you may see when your phone doesn’t charge if it’s only slightly out of place.

What About Fast Wireless Charging?

Over time we have seen wireless charging speed up. At the start, wireless chargers delivered only 5 watts, which is a low ball in comparison to wired charging. Today some wireless chargers support 10, 15, or up to 30 watts.

In order to support these higher speeds, manufacturers have improved upon coil design, optimized power delivery systems, and also improved in the area of better heat management. However, it’s still not as fast as the best wired chargers which can go over 65 watts.

Additionally, the faster you try to charge wirelessly, the more heat is produced. This is the reason some pads include fans which are built in or special materials which aid in the cooling process.

Is Wireless Charging Safe?

Sure. In general, what we see is that wireless chargers are designed with safety in mind. This includes:

• Foreign object detection: If at the time of charging we detect any metal (like keys or coins), we will turn off charging to avoid overheating.
• Temperature control: Chargers will shut off at signs of overheat.
• Communication protocols: Your phone and charger communicate to meet the battery’s requirements.

As long as you have a certified charger, the wireless charging is safe for your phone and you.

Limitations of Wireless Charging

Despite its convenience, wireless charging isn’t perfect. Here are a few issues:

• Reduced charging speeds as compared to the best wired options.
• Alignment issues can interrupt charging.
• During long and fast charge sessions, heat up may occur.
• While charging, you can’t leave your phone alone.

What’s certain is the ease of simply leaving your phone on the pad and walking away, which still has it over for many users.

Wireless Charging Beyond Phones

While phones are the main use of this technology, wireless charging is not limited to them. We see it in:

• Smartwatches
• Wireless earbuds
• Electric toothbrushes
• Some laptops and tablets

It’s still in its early experimental stages.

In each of these cases, the same principle of electromagnetic induction is used, though at different scales.

The Future: Wireless Charging?

On the horizon is something very exciting: true wire-free charging. Companies have played with charging devices which use radio waves or infrared beams to do the job, which in turn allows you to charge your phone from across the room.

Also, at present this technology is in development. Issues include:

• Safety concerns
• Signal interference
• Low efficiency
• Regulatory approval

Still, at present the concept is very promising and in the future may make today’s “wireless” pads out of date.

Final Thoughts

Wireless charging is a modern convenience which in actuality is based on very old science. We see through the use of magnetic fields and coils that we are now able to charge our devices without the need for plugs.

While there are issues which we should be aware of, wireless charging has brought a great deal of ease and convenience to our charging routine. As the tech grows, we will see faster speeds, wider range, and better integration across all of our devices.

Presently, each time you put your phone on the pad and it lights up to begin charging, you’re witnessing a wonderful blend of smart engineering and classic physics at work which brings it to you.