Wireless phone charger. Wireless phone charging - how it works. How Apple's opinion on wireless charging has changed

How does wireless smartphone charging work? August 21st, 2016

Nowadays I hear more and more often about wireless charging. Four months ago, when I was looking for a new car, I saw a Kia Sportage with a built-in charger. I also thought, who is this intended for, just a few? It seemed that for this you need to have some kind of cool phone model or some expensive equipment. But it turns out that my average-priced phone also supports this technology. I thought about it, I don’t know the principles of how it works at all. It seemed to me that this technology is still quite “far” from the average person, but it is already nearby and completely accessible.

Let's take a closer look...

It turns out that the principle of operation of a wireless charger is very simple - just place the gadget on a special panel for it to charge. The accessory is based on the operating principle of an induction coil.

Wireless toothbrushes have been using wireless charging for a long time. The technology has traditionally been plagued by problems of low efficiency and slow charging, but these weren't critical shortcomings for a toothbrush or electric razor that you only use for a few minutes every day. Using inductive charging is safer from the point of view that there is no wire to short out and you won't accidentally touch areas with poor insulation with wet hands.

This method of energy transfer has become very popular recently. In 2015, the globally popular brand began selling furniture that would have a wireless charging module built into it. Today, all flagship smartphone models support Qi.

It is expected that transmitters, or, in other words, modules, will soon be found in airports, restaurants, cinemas, fast food outlets, and shopping centers, which will allow phones and tablets to be charged at any time. In fact, this will make life easier for users of mobile gadgets. We are entering a new era where it is not necessary to carry wired chargers everywhere with us for all the devices we use.

The wireless power standard is called Qi. In Russian transcription the word is pronounced as “Qi”. The standard bears this name in honor of the term of Eastern philosophy and means the flow of energy. It is developed by the Wireless Electromagnetic Power Consortium WPC. This organization unites global electronics manufacturers and sets itself an important task - to standardize the process of charging gadgets using the induction method. In the near future, all devices will be able to be charged without connecting to the network. It's incredibly convenient. Each of us has at least once encountered a situation where a smartphone is discharged. We have to urgently look for a way out. Soon, wireless charging modules will appear in all public places, as well as in every user’s home.

At home, you can simply place the module in a convenient place, and it will never get lost, unlike wired “charging”. You just need to place the gadget on it and wait a bit until the battery capacity is replenished. The operating principle of wireless “charging” is based on the properties of an induction coil to transmit electric current. In a school physics course, we were taught that when an induction coil is connected to a power source, a magnetic field appears in it perpendicular to the turns of the coil. Thus, if you place two coils within the range of a magnetic field and at the same time connect one of them to a power source, then voltage will appear in the second coil. It is important to take into account the fact that the two induction coils should never touch each other. This simple principle is used in the operation of wireless chargers that support Qi technology.

There are two varieties of the Qi standard. The first involves charging at low power - 5 watts, and the second - at high power - 120 watts. High-power Qi is currently not produced by manufacturers due to objective factors. Using Qi at 120 watts, you can charge your laptop. Qi at 5 watts is used to replenish the battery capacity of tablet computers and phones. It should be noted that tablets and smartphones require different amperages. A wireless charger for a phone creates a current of 1 ampere, and for a tablet computer - 2 amperes. When choosing an accessory, be sure to pay attention to these characteristics.

A modern wireless charger consists of two components. One of them is built directly into the gadget, which supports Qi and is called a wireless charging receiver. Essentially, it is a receiver that conducts electrical current to the battery. The second component is called the transmitter. If you mean buying a wireless “charging”, we are talking about a transmitter. They come in a variety of shapes and sizes. The most common types are round and rectangular transmitters.

To better understand how wireless charging works, you should consider that a magnetic field can transmit not only electric current, but also data about bytes and bits, which the developers of the Qi standard took into account. Interaction between the coils will occur only at the moment when the gadget with a built-in transmitter is close to the transmitter. If the accessory for charging the gadget operates in the background, then the pulse sent every 0.4 seconds by the transmitter will not change the voltage in the coil built into the transmitter. We can conclude that a modern accessory can recognize in which mode to operate. As soon as a smartphone is nearby at a distance of a few centimeters, the voltage in the induction coil will drop sharply, and the device will go into active operation mode. As soon as the smartphone's battery is charged, a corresponding signal will switch the charger into the background. We can conclude that modern wireless accessories for replenishing battery capacity are energy efficient.

Even more graphs and formulas

Some users mistakenly believe that Qi wireless charging may be harmful to health. The fact is that magnetic radiation is not ionizing. In terms of its effect on the body, it is similar to a mobile phone signal, a Wi-Fi signal, or a radio signal. At the same time, the mobile network signal that comes from the tower is stronger and continuous, while electromagnetic radiation disappears immediately after charging the smartphone battery. The power of wireless chargers is 5 watts. It is not enough to have an effect on the human body. We can talk about a negative impact only if the power of such devices is 120 watts. But such models are not produced on an industrial scale. This explains the lack of wireless chargers for laptops. It is important to know that wireless battery charging technology has long been used in many models of electric shavers and electric toothbrushes, which once again proves its safety.

Prospects

This inductive charging can be convenient, but the short range is a problem. This dramatically reduces the usability of this technology. Will this change? May be. There has been a lot of research into the potential of wireless charging and there have been advances in range in various technologies. Lasers, microwave ovens, and more powerful inductive charging options have been able to achieve longer transmission distances. Disadvantages prevent the spread of this too powerful radiation of the above mentioned technologies. You might get burned or worse. It is difficult to say who will take the palm in this market. The first candidate is Apple, because the company has patented a device that can supposedly charge from a distance of up to one meter. The Wireless Power Consortium is also constantly looking for better options. And then there's Intel, which recently announced that it's working on integrated magnetic device technology that will fit inside a laptop and distribute power to nearby smartphones and peripherals.

sources

It would be great if you never had to charge your smartphone, or if it charged without any contact while connected to a Wi-Fi hotspot. Unfortunately, today no manufacturer can promise you this, but there is a way to forget about the need to connect a charging cable. We are talking about the so-called. Today, the Qi standard is actively developing, and many devices already support it. Let's figure out what it is and whether we should use it.

What is this?

So, as already mentioned, wireless charging allows you to top up your device's battery without connecting a power cable to it. However, a charging contact is still needed, and the device will not start charging until it is placed on a special charging platform or mat. Some devices natively support wireless charging technology, and the necessary elements are built into the case, and some devices can be taught to charge wirelessly using a special case, which, however, seriously increases their size.

Supported devices charge using induction, which means the element needed for wireless charging is nothing more than a coil that is charged using electromagnetic fields. This process occurs unnoticed by the human eye. The only thing you will see is a battery charge indication on the smartphone screen.

Why is this necessary?

In fact, using the charging cable is not convenient enough. Cables become frayed, tangled, and lost. It is much more convenient to have a platform that is always in one place, at home and at work. The Qi standard is widespread today, and today wireless chargers can be found in cafes, hotels and many other places. This is more convenient than looking for a socket and cable suitable for your smartphone.

Finally, the last and most unobvious advantage can be appreciated by owners of devices protected from moisture. When there is no need to connect the cable, there is no need to open the plug on the case, which wears out quite quickly and is not very convenient.

What are the disadvantages?

I would like to say that there are none, but this is not so. The main disadvantage of wireless charging technology is that it is less energy efficient. The smartphone will not charge as quickly as when connecting a cable, and the electricity will be spent less efficiently, and some of it will be lost in the form of heat. However, slow smartphone charging should not bother you if you can always place your smartphone on a mat at home or at work.

Another disadvantage is the rather high cost compared to conventional chargers. This is a more complex technology, and this leads to another nuance. Wireless charging is quite difficult to integrate into a device that is too thin.

Which devices support wireless charging?

Almost every modern device supports wireless charging, but some, like the iPhone, won't charge without an additional accessory. Devices from Asus, Google, BlackBerry, HTC, Cat, LG, Kyocera, Motorola, Nokia, Samsung, and Yota Devices support wireless charging. A complete list of such devices can be found here.

Based on materials from AndroidPit

A contactless charger is a dream for every smartphone owner. Modern phones need to be charged regularly. You constantly have to connect them using a wire to the adapter. However, now you can choose wireless charging and forget about all the difficulties. Wireless phone charging is no longer a dream, but a common device used by millions of users.

For many decades, people have dreamed of the possibility of transmitting energy over a distance. This can often be found in fantasy novels of the 20th century. And then it happened. Chargers have come into use that charge consumer batteries from a distance. True, the distances are still very small, only a few centimeters, but this is already a confident step forward. And not theoretical, but practical.
At the moment, wireless contactless chargers for smartphones (BZU) are the most widely used. Just put your smartphone on the charger and it will start charging. No wires are needed from wireless charging to your smartphone. Everything works on the law of mutual induction. The phone rang, you calmly pick it up without fear of getting tangled in the wires, without fear of damaging the connector contacts, and you are also not strictly tied to your workplace.
So, at the moment, wireless chargers are no longer a myth. These are adapters that anyone can purchase. You can place the charger on a table by your bed at home or in a car on the dashboard.
But it is worth noting that not all phones and smartphones produced by various manufacturers are capable of charging from wireless chargers. Phones that support wireless charging have only recently begun to appear. You can find out which phones support wireless charging from the mobile phone store manager. But if your phone does not support this function, then I will describe below how to upgrade your phone or smartphone for these types of charges.

Principle of operation

The principle of operation of a wireless charger is based on the laws discovered by scientists Tesla and Faraday. These are the so-called phenomena of induction and mutual induction. Remember school physics. If current flows through a conductor, a magnetic field appears around the conductor. If another conductor is introduced into a magnetic field, an EMF (Electromotive Force) is induced in it.

All transformers operate on this principle. If alternating current is applied to the primary winding of a transformer, a current is generated on the secondary winding, the magnitude of which will depend on the number of turns in the secondary winding. Wireless charging works on the same principle. And I will try to explain how wireless phone charging works. The source of electromagnetic radiation is the induction coil, which is located in the charger (acts as the primary winding of the transformer). Looks like a stand, charging cup or something similar. Connects to the mains directly or via an adapter. The device being charged also has its own coil (similar to the secondary winding of a transformer). If both coils are located at a sufficiently close distance from each other, then an alternating current is induced in the second coil, then it is rectified into a direct current and charges the gadget’s battery through the charge controller.

Any contactless charging for a phone or other device works on this principle, be it in a home or car. Most often we come across devices of the QI standard.

Wireless charger standards

Qi
The most common wireless charging standard is Qi. This standard was developed by the Wireless Power Consortium, abbreviated WPC, and is supported by many manufacturers such as Samsung, Nokia, LG and others. The Qi standard is read as Qi, which in Chinese is equivalent to the word “life.”

The operating principle is based on the law of mutual induction, as described above. The operating frequency of the BZU is 100-205 kHz. Efficiency 75-80%.
P.M.A.
Another popular standard is called PMA. Its principle also includes the law of electromagnetic induction. This standard was developed by Powermat in 2012. It is not as popular as Qi, but it also has its advantages.

The company focused its main efforts on developing a better electromagnetic field transmitter. And the operating frequency of the charger is 277-357 kHz.
This standard is mainly used in the USA. But still, the PMA standard is quite inferior to Qi.
Rezence (A4WP)
The operating principle of the Rezence standard is based on the law of magnetic resonance. This allows you to increase the transmitted power to 50 W, which is enough to charge more powerful devices, and even several devices at the same time. You can also increase the distance from charging to the gadget being charged.

But so far this standard is more theoretical and does not receive widespread support.

Where are wireless chargers used?

Since the invention of wireless charging, it immediately began to be implemented by all kinds of manufacturers to charge the batteries of various devices.
Toothbrush manufacturers were among the first to introduce wireless charging. The fact is that toothbrushes come into direct contact with water. This is where the invention of the BZU came in handy. After all, these devices do not have bare contacts. The toothbrush and charger have a good seal.

Apple Corporation is also keeping up with progress. They have introduced wireless charging for their Apple Watch.

But the most popular are wireless chargers for smartphones. What a convenience. Just put your smartphone on the charger and the charging process begins. No wires. The majority of smartphones with such chargers were released by Samsung. Nokia also released smartphones with such chargers. In 2017, Apple released the iPhone 8 iPhone X, which can also be charged from a charger.
Often such devices are installed in public places. In cafes and restaurants, people are used to working using smartphones, communicating or having fun. The Internet takes up quite a lot of battery power.

To attract visitors and ensure that guests stay as long as possible in these establishments, the owners offer free Wi-Fi, but also, of course, contactless chargers for smartphones, which are built right into the establishment’s tables.

Many manufacturers also produce wireless car chargers for phones. The principle of wireless charging is very simple. The wire from this charger is inserted into the cigarette lighter socket, the charger itself is installed in a convenient place, taking into account that the phone will not fall off it while driving.

Benefits of wireless charging

There are a lot of advantages to being able to charge your phone using a contactless method. First of all, the main problem is solved, namely the adapters. Now there will be one universal panel for all devices at once. The wires will not wear out and the sockets on the mobile phone will not break too quickly. This is also especially important for a charging iPhone, because its repair is expensive.
When choosing a specific adapter, you can’t help but think about the advantages of contactless:

Convenience. Can be used anywhere.
It is possible to charge several phones at once.
Over time, there are more and more devices that support this function.
A minimum of electricity is wasted, although the efficiency of this charging is about 80%.
Samsung and some other companies plan to offer a similar adapter with the phone.
Durability. The charger can last for many years.

Manufacturers

Many companies have taken up the issue of creating and developing contactless chargers for phones. Each of them is focused on specific features and is ready to satisfy the specific wishes of users. First of all, you need to consider chargers from smartphone manufacturers that have wireless charging enabled.

How to improve your smartphone yourself

As I wrote above, not all smartphones can work with contactless chargers. There is no receiving part inside these smartphones. But this is not a sentence. Today, in addition to wireless chargers, there are also separate receiving devices on the market.

They look like a sheet of cardboard the size of a matchbox. Inside this plate there is a receiving coil. The receiving part is of two types. The first option is that the receiving part is placed under the battery compartment cover of the smartphone and is connected directly to the battery.

The second option is that the receiving part is connected to the input connector and covered with a smartphone case.

Yes, there is another option. Smartphone cases with a built-in receiving part are available.

How to choose

Experts advise that before deciding which contactless phone charger to choose, decide whether the gadget supports this technology. Apple is specifically categorically against this practice, because they are focused on using original contactless adapters. However, Samsung and many other manufacturers do not need such careful selection. Many gadgets accept modern phone chargers from different manufacturers.

Be sure to watch the video review of wireless chargers

With the announcement of integrated wireless charging in the Lumia 920, Nokia hopes that this technology will attract the attention of buyers and win some of them away from Apple. Nokia has joined HTC, Sony, Samsung and others in adopting QI, a proprietary standard interface created by the Wireless Power Consortium. Qi, pronounced “qi,” comes from Chinese energy flow and is designed to power devices through magnetic induction. Let's look at what it is and what benefits it provides.

Operating principle

The term "wireless charging" usually refers to inductive charging. This technology uses a charging station that creates an alternating magnetic field. A device with an appropriate induction coil will receive energy from the field induced by the field charging station, and thereby the energy can be transferred over a short distance. Everything is as the great Nikola Tesla said. Or maybe the Tunguska meteorite is really his doing?

Disadvantages of wireless charging

Inductive charging depends on the magnetic field. They can be strong, of course, but still have a short range. This is the first drawback.

Charging speed and efficiency are the second drawback. Charging devices using inductive charging is not as efficient as using a direct, physical connection.

The third disadvantage is dimensions. Even though coils are small and getting smaller, a significant portion of the space available in a modern smartphone, tablet or ultrabook will still be coils. This is a problem that will decrease over time, but today it is still relevant.

The future of wireless charging

It is difficult to say who will take the palm in this market. The first candidate is Apple, because the company has patented a device that can supposedly charge from a distance of up to one meter. The Wireless Power Consortium is also constantly looking for better options. And then there's Intel, which recently announced that it's working on integrated magnetic device technology that will fit inside a laptop and distribute power to nearby smartphones and peripherals.

Conclusion

Wireless charging has huge potential. That's why people have been working on it for over a century. If we could transmit energy wirelessly, we could reimagine not only consumer electronics, but the infrastructure used by humanity. A list of smartphones that support wireless charging is presented

Wireless charging technologies for electronic devices have been developed by manufacturers for a very long time. Perhaps the most familiar popular option for their actual use can be considered some models of electric toothbrushes. In this case, the advantage of this solution, in addition to the convenience of charging, is the absence of external electrical contacts, which are not very practical in a bathroom. It is also worth paying attention to the regular operation scenario of this device and the absence of the need to charge the brush in other places.

However, the smartphone market has not yet seen widespread use of similar solutions, which look very convenient. In our opinion, there are several reasons for this. The first two are quite typical for most new technologies: an increase in cost and a small number of available “response” parts - the wireless chargers themselves. But the more important reason is the significant change in the mobile device charging scenario. When using a cable, you lose only one thing - the ability to move your smartphone over a long distance. Moreover, in most cases this is not very significant (in addition, you can simply use a long cable). At the same time, you can continue to use telephone conversations, the Internet, mail, multimedia and all other applications. You can't do this with wireless charging. It necessarily requires the smartphone to be on a special stand while charging. Although, of course, you can imagine an option with a speakerphone or headset.

It turns out that actually wireless chargers may only be interesting in a limited number of scenarios - for example, in a charging dock at night or when navigating in a car. For frequent everyday or emergency use today, they are not very convenient. However, the option of chargers in cafes that are already being tested may also prove useful. Over the past few years, smartphones have received bright high-resolution screens with large diagonals and powerful multi-core processors, but the active operating time on a single battery charge has remained virtually unchanged. If they were able to guarantee that they would last more than a day, the situation would be different - the user would only need to use a wireless charger at home, placing the smartphone on it overnight. It should also be noted that for popular devices such as tablets, the use of wireless charging is less likely. In particular, they require a higher power supply than smartphones, and in addition, the stand will be too large. (By the way, it should be noted that during testing we came across the fact that in some combinations, a certain fixed position of the smartphone on the stand is required for operation.) The use of wireless charging with headsets or other accessories is also unlikely; the reason for the lack of such solutions will be the inability to use sufficiently large receiving coils in these devices.

In general, the following advantages of a wireless solution can be noted:

no mechanical/direct contact;
possibility of use in hostile environments;
ease of use (in some cases).

However, there are also disadvantages:

less efficiency;
long-term charging;
increase in the cost, weight and size of a smartphone;
inability to fully use the smartphone while charging.

But we must admit that recently there have been certain changes in this area. Not every manufacturer, even the largest, has the strength to create a truly universal solution. We can consider that standardization began in 2008 with the creation. The option they developed, called Qi, is today the only solution recognized by a large number of market players. In total, according to the consortium, at the time of writing, almost 200 companies were represented in it, and there were more than 350 products on the market that support this standard. Qi can be found in products from HTC, LG, Motorola, Nokia, Philips, Samsung and other manufacturers.

Another organization in this area is formed in 2012. Its member Qualcomm is currently offering its implementation of a technology called WiPower.

It is also worth mentioning, created in 2012, which also aims to develop and promote an industrial standard for wireless charging. Following him, a working group was organized in October of this year.

Currently, you can find Duracell Powermat products on the market, but they are not widespread and are not used by smartphone manufacturers, so later in this material we will consider Qi solutions.

Technically speaking, a wireless charger uses an electromagnetic field to transfer energy from one device to another. If we talk about the current Qi implementation, here in the low power section the following characteristics are set: distance of about 5 mm, maximum power 5 W. Let us recall that a power of five watts corresponds to the most common wired chargers with a USB interface and a current of 1 A. In addition to the coils themselves, the process involves special controllers that monitor the supply and reception of energy, and the controller is a unit installed in the mobile device.

Below we will look at three solutions of this standard from different manufacturers in terms of ease of use, charging speed and compatibility.

Nokia

Nokia offers two accessories to enable wireless charging of its devices: Nokia Wireless Charging Plate (DT-900) and Nokia Wireless Charging Pillow by Fatboy (DT-901). They differ only in design: the first is a strict device made of plastic, and the second is a soft and flexible “pillow”. Both models come in several vibrant colors to match the Nokia Lumia lineup. The remaining characteristics are the same: support for the Qi standard, an external power supply 12 V 0.74 A with a cable 1.8 m long.

In testing we used the DT-900. The stand body is made of plastic, in our case bright red. Its dimensions are relatively small - about 120x60x11 mm.

The upper matte surface has the manufacturer's logo in the center, around which there is a low rubber edge. It allows you to keep your smartphone on the charger. Note that the large dimensions of the panel roughly correspond to a smartphone with a 4.5″ screen diagonal. So modern large devices will cover it completely.

The edge and bottom surface are made glossy. On one of the short rounded ends there is a power supply input, and on the opposite side there is a white charging indicator. At the bottom of the panel there is a rubber insert that prevents slipping.

The included cable is red, but the power supply itself is white. It is worth paying attention to the parameters of this unit - it produces 12 V 0.75 A, which is significantly more than standard wired chargers produce. In particular, the standard AC-16 is designed for 5 V 1 A. It can be seen that the power losses are significant.

The list of compatible devices includes models from Lumia 720 and higher. However, only the Lumia 920 has a built-in receiver; for the rest, you will need to purchase an additional back cover, which communicates with the device through contacts located on the back of the smartphone. In particular, when working with the Lumia 1020, the cover increases the weight by 30 g and the thickness by about 2 mm. Perhaps this solution is more interesting than the built-in module in the Lumia 920. At least until such technologies are used everywhere.

The device turned out to be quite convenient to use. Its small size allows you to easily place it on a table, bedside table or shelf. The built-in indicator lights up during charging, which begins literally a couple of seconds after placing the smartphone on the stand. Please note that if you use large smartphones, this indicator may not be very visible. It is also worth paying attention to the non-standard power supply and connector. The other models reviewed in this article can be “transformed” into regular chargers and used with most smartphones by simply unplugging the Micro-USB cable from the cradle.

We conducted the first charging test together with the Nokia Lumia 920. The test showed that the wireless charger is capable of working even with a completely discharged device, which, undoubtedly, should be considered a plus of the solution. As for the time to fully restore the charge, with the DT-900 it turned out to be almost the same as with a standard wired power supply - about two and a half hours. So the charging speed in this case can be considered high, but the main thing is that it will be convenient for the user to predict the required time, since it does not depend on the option used.

Compatibility testing with the Samsung Galaxy S4, equipped with a proprietary wireless charging cover, was successful. The smartphone was able to fully restore its charge in about 3 hours and 10 minutes. It is also possible to start working with a completely discharged battery.

Note that Nokia has an unusual model of an external battery with wireless charging - Nokia Portable Wireless Charging Plate (DC-50). The cost of the Nokia DT-900 at the time of writing was about 2,600 rubles. Branded covers with receiving modules were offered for 1000-2000 rubles, depending on the model.

Samsung

Samsung chose a slightly different approach to packaging. Its S Charger Kit accessory includes a charging stand and a new smartphone cover with built-in charging circuits.

When used with the Samsung Galaxy S4, it increases the weight of the device by 20 g and the thickness by about 2 mm. It is interesting that the currents are indicated on the components: 5 V 2 A is required at the input (this is what the standard unit from this smartphone produces), but at the output you can only get 5 V 0.65 A.

The stand body is made of plastic. Its dimensions are about 161x91x12 mm. The top panel uses a gray semi-gloss material. Its concave shape helps to hold the smartphone in the desired position. The manufacturer's logo is visible in the center. However, if we talk specifically about the Galaxy S4, then it is noticeably smaller than the stand - the dotted line exactly corresponds to the size of the smartphone.

The main body is glossy white. In the center of one of the short ends there is a Micro-USB socket. To the side of it, on the top edge, there is a green LED, which lights up when the smartphone is placed on the stand and charging begins. The location for the indicator is not very well chosen - it would be more convenient to see it on the opposite side. However, due to the large size of the stand this is not very significant. Most of the bottom is made of rubber, which allows the stand to stay firmly on the table.

The time to fully charge the Samsung Galaxy S4 is about three and a half hours. Testing the operation using a 1 A power supply showed that, in fact, the requirement for a two-amp model is not justified; a less powerful unit will be quite sufficient. This replacement does not affect the duration of wireless charging. Note that this configuration is also capable of restoring a completely discharged smartphone.

Let us remind you that when using the supplied wired charger, the charge recovery time is about two and a half hours. At the same time, up to 90% the charging speed is quite high, but at the last ten percent it decreases.

In domestic stores, this kit is offered for about 3,000 rubles.

PowerQi

The presence of a standard allows different companies, not just smartphone manufacturers, to produce compatible devices. In particular, we managed to find an almost “nameless” version of the PowerQI T-100 wireless charger for testing.

The package includes a stand, a power supply (5 V 1.5 A) with a Micro-USB cable and a special receiver unit. The last element is usually individual for each smartphone model; in our case it was the antenna and control unit for the Samsung Galaxy S4. The approximate cost on foreign trading platforms is $35 for a charger with a power supply and $10 for a receiver unit.

The stand is made of white glossy plastic and has dimensions of 150x80x10 mm. The flat top has slightly beveled edges and lacks any rubberized elements, so it doesn't hold the phone in place very well. The panel is painted in gray paint with the name of the company and model, as well as the logo of the wireless charging standard. The stand rests on four rubber feet.

The LED lights up green when there is external power, and when the smartphone is installed for charging, it changes color to blue. We also note that a sound signal sounds at this moment, which allows you to be sure that the device is recognized and charging begins.

The receiver unit consists of a flat antenna and a small board with a controller manufactured by Texas Instruments. It is supposed to be installed under the standard cover of the smartphone with connection to the contact pads present on the case.

Note that the output current indicated on the receiver is 600 mA. For smartphones that do not have this capability, there are options in the form of cases with connection via a standard Micro-USB. Interestingly, this antenna seems to be slightly smaller in size than the standard Samsung accessory; this may require more precise positioning of the smartphone on the transmitter. In our testing, this situation arose with the Nokia charger due to its compact size.

Charging time for a smartphone with a proprietary cover on a PowerQi stand is approximately 3 hours 30 minutes, so from the point of view of transmitters, these models are the same. Other combinations of receiver and transmitter give similar results, including the ability to restore the charge of a smartphone with a completely discharged battery.

Conclusion

Many companies today are showing interest in wireless charging technologies for smartphone batteries. However, no revolutions should be expected here. There are many players in the market, it is difficult for them to come to an agreement with each other, and in addition, the familiar “chicken and the egg” problem arises. So today, it’s probably not worth considering the presence of a built-in or optional wireless charging module as mandatory for top-end devices.

In this article we looked at several solutions developed according to the Qi standard. They showed good compatibility and were generally quite functional. The only cause of some concern is the relatively low possible power in this Qi modification, which does not allow for rapid charge recovery of modern devices with high-capacity batteries. However, if we consider these solutions as a night charger, they will be quite sufficient for most smartphones. As for active work scenarios, for example, navigation in a car, it is quite possible that the wireless docking station will not be able to restore battery charge while simultaneously running resource-intensive applications, but will only act as an additional power source, reducing the rate of discharge of the standard battery .

In any case, Qi technology can be considered quite mature and suitable for use not only by enthusiasts, but also by ordinary users who find this scenario useful for themselves. Moreover, it is not at all necessary to use original accessories - solutions from lesser-known companies offered on Internet sites at a relatively low cost may also be suitable.