How does wireless charging for smartphones work? Wireless phone charging: how it works, how to use it

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Wireless charging technology appeared several years ago, but until now it has not been widely used in the smartphone market. Lumia 920 and 820 became the first Nokia smartphones, which implement wireless charging.

All you have to do is place your phone on the DT-900 Platform, DT-910 Stand, Fatboy Pillow or JBL PowerUp Speaker and your phone will start charging immediately.

How does wireless charging work?

Wireless charging is a transfer method electrical energy through the air to the device being charged. The device will charge without directly connecting it to the network. The charging process required a complicated technical solution. The diagram below shows the basic principle of inductive transmission of electricity.

The transmitter coil L1 is located at the bottom, and the receiver coil L2 is located at the top. L1 is in the charger, L2 is in the smartphone. Alternating current in coil L1 generates a magnetic field, which causes voltage to appear in coil L2. This voltage is used to charge the device's battery.

Nokia wireless charging devices use Qi (read [chi]) technology, developed and used by more than a hundred companies around the world. This is a globally recognized standard, so your device can be recharged anywhere with it. globe.

Nokia has already entered into agreements with Coffee Bean, Tea Leaf and Virgin Atlantic - these companies will provide their customers with the ability to charge Lumia 920 and 820 smartphones using wireless devices.

Each Nokia charger has its own characteristics.

The DT-900 is a standard but attractive platform. While charging on the DT-910 cradle, the phone can be used for video calls or working with applications. The Fatboy pillow is suitable for those who like unusual things. JBL PowerUp speakers will play music while your phone charges.

Nokia has tried to make the wireless charging process more convenient than its competitors. Active area charger increased to 80% so that the user can simply place the phone on the platform without spending extra time on its correct placement.

You can purchase all these chargers in stores that sell Lumia 920 and 820 smartphones.

Progress does not stand still. The field of high technology is one of the fastest growing - almost every day there is news about new developments and technologies that will make our lives easier. Wireless charger, which has gained popularity recently, is one of them. We'll talk about it today.

How does the technology work?

Before we talk about the pros and cons, let's understand how a wireless phone charger works.

Wireless charging (or QI as it is also called) works using the principle of electromagnetic induction. The receiver (smartphone, tablet, laptop) and transmitter (charger or panel) must have induction coils. Without going into details, if we apply current to a coil, we get an electromagnetic field. So, if we place any conductor in this field, then we get electromotive force. And she will already create the final link - electricity, allowing the battery to charge. That is, the receiver and transmitter communicate via electromagnetic field, which can pass through various materials (plastic, wood, etc.)

To some, this explanation may seem overly technical and complicated. In fact, for the average user it is not necessary to go into technical nuances. All he needs to know is how to place his device (smartphones, tablets, toothbrushes, electric shavers, and even some furniture already support wireless charging) on a specialized charging panel and remove it from there when the required charge level is reached. As you can see, everything is quite simple.

Advantages and disadvantages

The advantages include:

There is no need to constantly use wires, which sometimes cause discomfort, getting tangled, clinging, getting lost in the most inopportune moment. In addition, in the case of charging via QI USB connector will serve you much longer.
For many, the ability to charge the phone from multiple transmitters will be a plus. Such a need may arise, for example, when moving to another room or another place in the room. Wireless charging eliminates the need to carry a charger with you.

Main disadvantages:

QI will take longer to fully charge your gadget than standard charging.
And yet, wireless charging will have one wire that connects the panel to the outlet.
Let's not forget about the cost. Today, the price of wireless charging exceeds the price of traditional charging, so not everyone can afford to buy it.
Magnetic coils in a smartphone take up a certain space, which increases the size of the device and reduces the possibility of integrating more powerful hardware into the smartphone. Last time this disadvantage not so significant, since the magnetic coils are becoming smaller and smaller.

Is wireless charging hazardous to health?

Current and potential users of the modern type of charging ask the question: can the use of a wireless device affect their health and the health of others? Let's see if these fears are justified. In short, no.

The wireless charger uses an electromagnetic field at a distance of just under 20% of the wavelength, which is not much, and the radiation is not ionizing. As you know, non-ionizing radiation is absolutely safe, unlike X-rays. The effect of charging on a person can be compared with the effect on human WI-FI router or cell phone, which do not cause significant harm with their radiation. For example, a smartphone transmits a signal to long distances, the power of a smartphone is about 1-2 watts. Yes, this is lower than the QI power, which is about 5 watts. But this difference in transmitter power is offset by the extremely short range of wireless charging, within which it is impossible to harm a person. As you can see, there is nothing to worry about.

Which devices support wireless charging technology?

In order to recharge a smartphone or tablet, a QI charger (panel) alone is not enough - support for the function is required in the smartphone (tablet) itself. Today, not all smartphones have wireless charging support on board. But most people can already boast of it flagship models. In the future, it is planned to add QI support to more budget gadgets when the technology reaches the masses.

List of models that support QI wireless charging:

Samsung Galaxy: S6/Edge/Plus; S7/S7 Edge/Note 5/7; S8/S8 Plus;
Motorola: Droid Bionic; Droid 3; Droid 4; Droid Mini; Droid X;
Panasonic: P-02E, P-06D;
LG: Revolution; Spectrum; Spectrum 2; Optimus 2; Lucid 1; Lucid 2; LG G2; Optimus G Pro; Optimus Pro; Optimus IT; L-05E; LG G3;
Google: Nexus 4/5/6/7;
HTC: Thunderbolt; Incredible 2; Rezound 8X;
Sony: Xperia Z;
ZTE V975: Geek;
Blackberry: 9700.

Apple still ignores wireless charging and we can only guess whether the IT giant will include this feature in the new iPhone and iPad models. Perhaps in the near future we will see wireless charging in the Cupertino company’s own implementation. In the meantime, fans of Apple products can take advantage of the cases on sale with an integrated QI charger that connects to the iPhone using a lightning cable.

Upd. After the release of the iPhone 8, iPhone 8 Plus and iPhone 8 X, Apple introduced wireless charging into its new products. The glass backs of smartphones contribute to this. Yabloko uses for its devices open standard QI.

Future prospects

What are the prospects for wireless charging? Will this technology conquer the market? Let's speculate.

Already today, the mass consumer has access to chargers from $10-15, such as PowerBot, which has a good reputation due to its reliability and price-quality ratio.

There are also much more expensive solutions, such as Cota, which costs around $100. The main advantage of Cota is its small size (can be compared to a bread box) and large range. However, it is worth considering that not any device can be charged Cota, but only one equipped with a special Cotta receiver, and not every person can afford to buy such an expensive device.

You probably don’t need to be an expert to see the great potential of wireless charging of gadgets, because it’s really convenient: you don’t have to pull wires or try to get into the USB connector (it’s not always possible to get into the wrong side).

But let's face it, the technology still has some drawbacks. The problem is the very limited range. In ongoing studies, it was possible to expand this radius to 10 meters, but at such distances, manufacturers cannot guarantee absolute safety.

Intel recently announced that it is working on embedding a magnetic device into a laptop, from where it will share its charge with nearby QI-enabled devices. Every year everything appears on the market more devices with wireless charging function. Considering that such industry giants as Apple and Intel have taken up the development of the technology, we can confidently say that it has a great future.

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 such a 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 more important reason is a 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). However, you can continue to use telephone conversations, 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 in fact, wireless chargers can only be interesting in limited number 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 become bright screens high resolution with a large diagonal and powerful multi-core processors, however time active work from one battery charge there was practically no change. 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 found 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 receivers 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;
impossibility full use 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. It can be considered 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 with 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 currently offers 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, in October of this year, was organized working group.

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 are available in several bright colors, corresponding to the line Nokia Lumia. 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 of the Lumia 920. According at least, until similar technologies will not be used everywhere.

The device turned out to be quite convenient to use. Small sizes freely allow you to 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. Note that if we 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 time full recovery charge, then 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 is 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 in its arsenal 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 of this smartphone), and the output can only get 5 V 0.65 A.

The stand body is made of plastic. Its dimensions are about 161x91x12 mm. For top panel Gray semi-gloss material was used. 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 upper 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 big size stands are not very important. Most of the bottom is made of rubber, which allows the stand to stay firmly on the table.

Full time Samsung chargers 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; even less would be sufficient. powerful block. 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 us to produce compatible devices to different companies, not just smartphone manufacturers. 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 special block receiver 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. By cost in foreign countries trading platforms approximate guidelines are $35 for the charger with power supply and $10 for the receiver unit.

The stand is made of white glossy plastic and has dimensions of 150x80x10 mm. Flat top part It has slightly beveled edges and lacks any rubberized elements, so it doesn't hold the smartphone 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 the submission sound signal at this moment, which allows you to be sure that the device is recognized and charging begins.

The receiver block is a flat antenna and small fee 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. I wonder what this antenna The size seems a little smaller than the standard one Samsung accessory; this may require more precise positioning of the smartphone on the transmitter. In our testing, this situation arose with the charger Nokia device 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 fast recovery charge 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 a wireless docking station will not be able to restore battery charge while simultaneously running resource-intensive applications, but will only act as a additional source power supply, 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 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.

Situations arise when the cable for charging a gadget cannot provide power due to the fact that there is no outlet or there is no electricity. Then a wireless phone charger will come to the rescue, it works autonomously and does not take up much space.

How does a wireless phone charger work?

The operating principle of the device is based on QI technology. It involves the absence of wires or the use of contacts; its operation is based on the action of electromagnetic waves. The question of how wireless charging works can be answered - according to the principle of an inductive coil, a magnetic circuit. The device consists of 2 coils - transmitting and receiving, the first is needed to create an electromagnetic field, and the second - for current. Interacting with each other, they create a current through the transmitter, receiver, stabilize it, bringing it directly to the smartphone.

To charge your phone, you just need to place it on a special stand. Charging can be carried out and maintained anywhere - at home, in the car, or taken with you on trips or long trips. Some countries install similar devices in cafes, when a person arrives there, and while waiting for an order, charges the phone. It turns out simple, fast, convenient.

What are the advantages of a wireless charger?

The advantages of the charger include:

ease of use when it can be used at home, in the car or in a cafe;
the ability to charge several gadgets at the same time;
phones with wireless charging are increasingly being released;
the charge is made at a distance of up to 4 cm or closer;
charging consumes the minimum possible energy;
its electromagnetic field is safe for humans;
for some models it is sold immediately as a set with a cell phone, so as not to buy additionally;
automatically turns off when reaching 100% charge;
low cost, long term suitability.

How effective is a wireless phone charger?

Wireless phone charging is not without its disadvantages:

It can only be used to recharge certain models gadgets. So, you can’t charge an iPhone through it, but you can charge a Samsung Galaxy or Nexus.
To charge some smartphone models, you will have to buy a special case through which the process will be performed. This includes certain costs.
Wireless phone charging charges at a slower rate than when in use standard cable.
While charging, the device and gadget become very hot.
When charging, the mobile phone may receive distorted radio signals.

Where to buy and how much it costs

Portable phone chargers are sold in regular electronics chains or online stores. The range of prices in electronics stores varies depending on the manufacturer: for universal chargers the cost ranges from 2 thousand to 2500 rubles, for branded ones - from 3 thousand rubles. In online stores you can buy a device much cheaper: for universal ones they ask from 900 to 2 thousand rubles, but branded ones are not sold or are offered at the same price as in large networks.

For those who want to save money, there is the option of making such a device with your own hands. If you are well versed in electronics and radio engineering, then it will not be difficult for you to find manufacturing diagrams that are on the network or available sources, purchase parts, and make your own device. A self-made charger will cost less, and will work no worse than the factory one.

Video: DIY wireless charging

The world is getting rid of wires everywhere. Stationary wired connection buried mobile devices, new standards are being actively implemented for data transmission cellular communications and Wi-Fi, you can broadcast sound via Bluetooth, and computer mice and cables are stripped of wires, replacing them with miniature radio modules. It’s time to leave inconvenient connections using wires in the past, but there’s just one problem that prevents this from happening. In order for electronic devices to operate, they require external energy. This is precisely the issue that wireless charging is designed to solve.

The first commercial electronic devices powered wirelessly were PC mice. They began to appear at the beginning of the last decade, but never replaced the traditional options, giving way to more convenient manipulators with a radio transmitter. And the roots of the research go back to the mid-19th and early 20th centuries, when Michael Faraday and Nikola Tesla experimented with wireless transmission of electricity.

To understand how does wireless phone charging work, it’s worth remembering the basics from the school physics course. Transmission using the electromagnetic induction (EMI) method turned out to be the most promising and feasible in practice. It is based on the phenomena of electromagnetism: when current flows through a conductor, an electromagnetic field is formed around it (the conductor). If another conductor gets into it, then it is exposed to this field and a current also arises in it. Correct configuration(using inductors) allows you to concentrate relatively powerful electromagnetic radiation into a small area.

Wireless charging, as a rule, is a docking station connected to a USB port or socket, to normal charging. It contains a multi-turn coil, a power converter and control electronics inside. Compatible smartphones, in turn, have the same coil inside, only wound from thinner wire. If you place your smartphone on the docking station, the coils begin to interact, and energy in the form of electromagnetic radiation is transferred from the stand to the smartphone. From the receiver, current is transferred to the battery contacts, replenishing its charge.

Wireless charging standards

To choose the right docking station, it is not enough to knowhow does wireless phone charging work. It should also be taken into account that there are different standards used by manufacturers. The first smartphones with support for wireless charging appeared back in 2008. The pioneer in the industry was Palm (I wonder if anyone else remembers this?). But her developments somehow did not receive proper distribution. Subsequently, two consortiums were formed in the market, engaged in improving technologies wireless transmission energy. WPC (Wireless Power Consortium), created in 2008, is promoting the Qi standard (“Qi” is energy, a term from Chinese philosophy). It was he who received maximum distribution.

A competing organization is PMA (Power Matters Alliance), which is developing an alternative. Oddly enough, it includes many companies that also support Qi. Therefore, many smartphones can, in addition to Qi, also support the PMA standard. Among such devices are the flagships Samsung Galaxy S5 (not all versions), S6 and S6 Edge, Galaxy S7 and S7 Edge. Although this is not a complete list of smartphones compatible with both standards.

More devices are compatible with the Qi standard. Among them - not only Samsung flagships, but also top Nokia and Microsoft Lumia, Motorola, Sharp, Google Nexus, LG, Fujitsu and others. To find out which standard is supported by your smartphone, it is recommended that you read the technical specifications in the instructions or on the manufacturer’s website. It is necessary that both the wireless charging dock and the phone comply with the same technology (Qi or PMA).

What else to look for when choosing a wireless charger

The main criterion for choosing wireless charging for a smartphone is the standard. But he is not the only one that matters. When purchasing, you should also pay attention to electrical characteristics charger. If the output voltage is standardized and is 5 V, then the current strength can vary from hundreds of milliamps to an ampere and more. Considering that the output current of a wired charger is 1-2 A, you need to choose a model with a charging current of about 1 A. The higher the value, the better, since a weak docking station will recharge the phone for too long.

Shape can also matter: Sometimes the design of the charger may simply not fit into the interior. Inclined devices are not always convenient in terms of stability. The most preferred are rectangular and round horizontal platforms.

Pros and cons of wireless charging for a smartphone

How does wireless phone charging work?– we figured out what the main nuances and subtleties of selection are, too. It remains to determine whether such a gadget is worth buying, or whether it will not justify itself. To do this, you need to familiarize yourself with the pros and cons to decide for yourself whether to buy Qi charging or not.

pros

Protection for smartphone interface connector. During the charging process, there is no risk of damaging the socket by accidentally pulling the cable. The connector experiences less wear and tear because it is used less often.
The ability to charge a smartphone without having a charger.Many establishments around the world, such as McDonalds or StarBucks, equip their tables with Qi docking stations. Thanks to this, you can have a snack or drink coffee while recharging your phone. IKEA is also promoting such chargers built into household furniture.
Always have a charged battery at home.Wireless charging allows you to recharge your smartphone on time by simply placing it on the docking station. If the phone is rarely used, and the Qi memory is always at hand, you don’t have to worry about the battery running out at the wrong time. A well-thought-out controller stops supplying current to the battery when it reaches 100%, so there is no need to worry about overcharging.
Safety.No matter how skeptics of induction technology oppose and claim the dangers of invisible “radiation” (where does it come from in an electromagnetic coil?), wireless charging is safer than wired charging. The risk of getting an electric shock from the network charger cable is negligible, but in the case of Qi it is even lower, since docking stations usually operate at 5 volts. As for induction, at such powers it is absolutely harmless to humans. During an MRI, the body is exposed to thousands of times more electromagnetic radiation.

Minuses

Loss of mobility. Electromagnetic radiation The docking station is quite weak and effective only at a short distance. To charge your phone quickly, you need to place it flat on the stand. Using the device while charging is problematic, if not impossible.
Low charging speed.The output power of wireless charging for a smartphone rarely exceeds 1 A. This means that a 3000 mAh battery will charge in about 3 hours under ideal conditions. And if you place your smartphone unevenly, the time can increase dramatically.
Limited compatibility.In general, relatively few smartphones support the Qi or PMA standard. Not everyone has compatible receivers or cases that allow you to charge your device without cables.
Large reel sizes.The problem of device compatibility is largely due to the relatively large size of the induction coils. If you strive to maintain their small thickness, remove more power current (more than 1 A) will not work. Increasing the size will inevitably lead to a thicker smartphone. In the race for every millimeter, manufacturers cannot always afford this.

What to do if your smartphone does not support wireless charging

The lack of support for wireless charging does not at all put an end to the ability to charge your phone without a cable. Third party manufacturers have developed special accessories designed for this purpose. They are divided into two categories.

Plates

Receiver plates for wireless charging are a thin plastic card, inside of which there is an inductor coil. Using a thin contact cable, it is connected to service contacts or a battery and neatly placed under the cover. The small thickness allows you to easily fit into a narrow gap. Such receiver plates practically do not weigh down the smartphone and do not affect its appearance. A significant limitation is only compatibility with a narrow range of models with a removable cover. Otherwise, you will have to disassemble the device and do some magic with a soldering iron.

Cases

iPhone smartphone owners also want to try wireless charging. But Apple smartphones have never had a removable cover. Their battery is hidden deep inside, there is little space there and you can’t just get to it. The way out of the situation is special covers. In their rear part there is the same plate inside, only the contacts from it are connected not to the battery, but to the Lightning connector. For this purpose, a corresponding plug is installed at the bottom of the case. The disadvantages of this solution are the increase in the size of the smartphone, as well as not the lowest price for beautiful cases with Qi wireless charging.

A compromise solution is a Qi plate that connects to the Lightning connector, but lacks its own housing. Thanks to its small thickness, you can put it under any case without limiting your choice. For Android smartphones, the case of which is non-separable, there are also analogues with a MicroUSB or USB Type C connector.