Qi wireless charging standard. Wireless charging of smartphones using the example of Qi standard solutions

The idea of ​​wireless energy transfer dates back to the 19th century, and was first demonstrated by the Serbian genius Nikola Tesla in 1893 at the World's Columbian Exposition in Chicago. The technology that seemed like a miracle has now become firmly established and is found everywhere, from funny but useless levitating light bulbs to truly convenient things like wireless chargers for mobile devices.

The technology of transferring energy to a smartphone battery without using a connector and cable appeared a long time ago, back in 2008, that is, just a year after the presentation of the iPhone and the birth of the smartphone market in its current sense. Manufacturers of devices and components created the Wireless Power Consortium, the purpose of which was to unite different manufacturers to create universal wireless charging technology. Thanks to this collaboration, Qi technology was born - read "Qi" (less commonly "Chi") and denotes "energy" or "life force" in Chinese philosophy. Thanks to the work of the Consortium, the requirements and principles of operation of devices and charging stations supporting the Qi standard were determined, as a result of which users today can use induction mats without regard to the smartphone brand and without changing accessories after purchasing a new device.

It cannot be said that after the approval of the Qi technology standard and the start of its use, all other companies curtailed their development. There is constant research being done that would provide significantly faster charging speeds or greater distance between the pad and the device - but none of this is ready for mass production and in the absence of worthy revolutionary ideas, more and more smartphone manufacturers are starting to implement support for the Qi standard. Even Apple and Sony “gave up” by adding support for wireless charging to the 2017-2018 smartphone lineup, and the list of outsiders so far only includes inexpensive Chinese brands that try to save on components or do not want to change the well-established production of the same type of aluminum cases. However, the situation may soon change, for example, according to rumors, the flagship Xiaomi Mi7 will support charging using the Qi standard.

The accessories market is also constantly evolving. Wireless stations are starting to be supplied for public spaces, induction pads are found in cars or sold as additional accessories for cars, and many solutions for home use are emerging. And most importantly, most often the prices for wireless chargers are not so high as to deny you the convenience of using them. Branded accessories from manufacturers can be sold at a very high cost (4-7 thousand rubles), but there are always alternatives from third-party manufacturers that are not inferior in design, quality and technology. For example, we are now testing the Expert NBE-WC-12-01 model (1890 rubles) with support for an extended version of the Qi Fast Charge standard and a current of 1.2A.

This Nobby model is a compact round platform. The manufacturer uses high-quality black plastic that is pleasant to the touch; there is also a luminous ring that changes color when the smartphone starts charging. The accessory does not take up much space on the table, and most importantly, it has a classic flat surface. This is true for smartphones like the Sony Xperia XZ2 with a curved back panel, which can roll off some charging stations, but rests confidently on Nobby accessories. There is no risk of putting your smartphone in the wrong way and then finding it next to the mat not charged.

We tested the Nobby device with the iPhone X, Samsung Galaxy S9 and Sony Xperia XZ2 - in all cases it was very convenient, since you do not need to look for a wire, connect and disconnect it, and you can put the smartphone on the pad at any time. In terms of speed, the Expert NBE-WC-12-01 model works as advertised and charges the smartphone really quickly.

As for the principle of operation of wireless charging, everything is quite simple. The base station consists of an induction coil that creates an electromagnetic field when alternating current is applied. The device contains a similar coil that can capture this field, converting the resulting energy into direct current - and transferring it to the battery for recharging. However, this is an explanation for the average consumer; techies know that in fact the system is more complex and it also uses current converters, rectifiers, controllers, voltage regulators and other circuit components. But is this really important for the average consumer to know? Other questions seem much more interesting: the impact on health, safety of use and restrictions.

Despite the appearance of an additional radiation source in the house, there is no need to worry about this. Qi standard charging uses non-ionizing frequencies, which are guaranteed to have no harmful effects on health. And both humans and small domestic animals. Over the ten years of work of the Consortium, many studies have been carried out, and all of them have confirmed the possibility of using charging stations without restrictions. As for safety, there is also complete order: charging is possible only with Qi-compatible devices, there is a temperature control system for sudden heating. Even if a foreign object gets on the charging mat, there will be no problem.

As for the limitations, the only thing that manufacturers cannot “defeat” yet is metal cases. From the first devices like the Lumia 920 to the iPhone X, smartphones have had to experiment with materials. Previously, it was plastic, which was used even in the premium segment, but now it has been replaced by more spectacular glass. Perhaps this is why iPhone owners have been deprived of the ability to charge their smartphones on mats for so long. At the time of the Quartet, Qi was not yet so popular, and after that the company relied on metal for a long time. Now, partly due to the desire of manufacturers to implement wireless charging and partly due to spectacular design, glass has become the most popular material for the back panels of flagships. The entire current iPhone line, Samsung Galaxy flagships, the latest Sony Xperia XZ2 and XZ2 Compact, LG V30 ThinQ and Nokia 8 Sirocco - these and other top devices support Qi technology.

As a result, we cannot think of any reason not to use Qi chargers if the smartphone supports this technology. A wireless mat is very convenient because you can simply place the device on it, rather than looking for wires and a connector. Accessories are inexpensive, they are harmless and safe. We have already mentioned the Nobby brand and decided to talk about how we use it in the editorial office. The Expert model was chosen as the best option for office use - at work, we most often charge only one device and higher speed is very important to us. For example, if you urgently need to get ready for a meeting. However, there are other wireless chargers in the Nobby range of accessories. For example, the Nobby Practic NBP-WC-10-01 model has an outgoing current of 1A (that is, it charges more slowly), but is equipped with two USB ports for wired connection of devices. This solution is well suited for home use, since it allows you to use only one outlet and wirelessly charge your smartphone and other devices such as smart watches or headphones.

Finally, you can get rid of wires once and for all: the new generation of mobile devices supports QI wireless charging technology. CHIP will tell you how it works.

Nokia Lumia 920 smartphone on a QI standard wireless charging device Smartphones, e-readers, tablets - many of us have been owners of these devices for a long time. Their batteries require regular charging, and this is quite a troublesome task. In many cases, it is a problem, since most smartphones are discharged in one day. Therefore, it is long overdue to find a solution that takes into account both our forgetfulness and the constant need for electricity from mobile devices. The ideal would be a device, upon contact with which the gadget would immediately begin to receive a charge. To achieve this, the Wireless Power Consortium, which unites more than 100 IT companies, including Sony and Panasonic, has developed a unified standard for wireless chargers. It is called QI (pronounced "chee"), which means "energy flow" in Chinese. The first version of the standard appeared in 2010, but the implementation of the technology was sluggish. It was only in mid-2011 that the American provider Verizon began offering QI-enabled smartphones, including Galaxy models from Samsung. In 2013, the situation will change, which will be facilitated by the appearance of QI smartphones in Russia: the new top model Lumia 920 from Nokia has built-in QI support, and the back cover for wireless charging is optionally available for the Lumia 820.

Fast recharge for smartphones

According to the QI standard, the charging current power for a mobile device should be no more than 5 W. The standard does not provide for a specific method of energy transfer, but currently the inductive charging method is implemented, with both the transmitter and receiver equipped with coils. An alternating magnetic field arises in the transmitter coil, to which alternating current is supplied. As soon as the receiver coil comes under the influence of a magnetic field, an alternating current also arises in it. For the most efficient energy transfer, it is necessary to ensure the best interaction of the receiver coil with the magnetic field. In this case, the optimal distance between the transmitter and receiver depends on the diameter of the coil. The size of the transmitter coil provided by the QI standard, depending on the design features of the transmitter, ranges from 30–80 mm. The required distance is approximately a tenth of this value, that is, both devices should be located close to each other. As the distance increases, the efficiency of energy transfer decreases catastrophically - from more than 70 to several percent. In addition, for optimal transmission it is also necessary to choose a good position of the coils in space. According to the QI standard, this task will be performed by a magnetic core in the center of the transmitter coil, which will be attracted to the magnet in the receiver.

Magnetic field as a means of communication

In addition to energy, a magnetic field also transmits information in the form of bits and bytes generated using phase modulation of the field. The connection between the transmitter and the receiver is established at the moment when a mobile device, such as a phone, is on the surface of the charger. The transmitter sends a pulse every 400 ms. If the voltage does not change, this means that no energy is being transferred. A drop in voltage indicates the presence of a QI-enabled receiver. After detecting the latter, the transmitter sends a more powerful pulse to “wake up” the receiver. He, in turn, “negotiates” with the transmitter about the charging conditions, that is, the required amount of electricity, current strength and frequency. After this, the energy transfer phase begins, the effectiveness of which the receiver reports to the transmitter every 32 ms, sending it data packets with information about errors that can be corrected if necessary. After the battery is charged, the receiver sends an “End Power Transfer” packet and the transmitter stops working.

The new version of the standard (1.1), which appeared in April 2012, provides for the use of more efficient chargers than the basic standard. Version 1.1 has a good chance of success, but not all companies are involved in the development and implementation of the technology: Apple does not support QI at all, and Samsung and Qualcomm are developing their own standard. Next year, Intel intends to begin producing ultrabooks with support for wireless chargers. To do this, the company will use a resonance method rather than induction, but it remains to be seen whether it will be QI compatible or not.

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 produces 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

Wireless chargers look like a panacea for those mobile device users who hate fiddling with wires. However, they should not rush to buy wireless chargers - first they need to make sure that the gadgets they own are equipped with the technology Qi and can interact with chargers like Wireless. In this collection, we will talk about modern smartphones that support wireless charging - perhaps our recommendations will help you choose a gadget that will not force you to constantly look for a power outlet.

• Battery capacity: 3000 mAh.
• :Qi/Powermat.
• Display size and matrix: 5.1 inches, SuperAMOLED matrix.
• Processor and graphics: 8-core Exynos 8890 + Mali T
• Availability of moduleLTE: present.

Price: from 44,900 rubles

The Korean manufacturer is one of three organizations involved in the development of innovative charging methods - including WPC, which created the technology Qi. Therefore, it is completely logical that all the latest flagships Samsung can be “powered” by wireless chargers - this applies not only GalaxyS7, but also models S7Edge, S6, S6Edge, S6Active.

S7 supports an alternative wireless charging standard – Powermat, developed PowerMattersAlliance, a consortium that also includes Samsung. Powermat- less common option than Qi, however, there is an opinion that his “golden years” are ahead. For popularization Powermat a famous coffee chain has come to the USA Starbuck's, which has already introduced wireless charging in some of its establishments.

Precisely because SamsungGalaxyS7 supports two standards, the model does not have a metal back cover, but plastic, covered with protective glass. Wireless charging through metal is currently not possible.

Advantages

Flaws

• The amount of RAM of 4 GB is a lot, but in 2017 there are already gadgets on the market that offer 8 GB.
• High cost – buying a gadget for 45 thousand is not affordable for everyone.

Motorola Nexus 6

• Battery capacity: 3220 mAh.
• Wireless charging standard: Qi.
• Display size and matrix: 5.96 inches, AMOLED matrix.
• Processor and graphics: Quad-core Qualcomm Snapdragon 805 + Adreno
• Availability of moduleLTE: present.

Price: from 18.5 thousand rubles

MotorolaNexus 6- a gadget with many “chips”, and one of them is the possibility of wireless charging technology Qi. Company employees Motorola And Google(who created the device together) generally tried very hard to ensure that the gadget spent as little time as possible connected to the outlet.

Included with MotorolaNexus 6 there is a powerful charger TurboCharger, capable of recharging the gadget from zero to 50% in just half an hour. The secret to efficiency TurboCharger lies in 15 W of power.

Advantages

Flaws

• Lack of card support MicroSD.
• The amount of RAM is small by today's standards - only 3 GB.

Sony Xperia Z4v

• Battery capacity: 3000 mAh.
• Wireless charging standard: Qi, PMA.
• Display size and matrix: 5.2 inches, IPS matrix.
• Processor and graphics: 8-core Qualcomm Snapdragon 810 + Adreno
• Availability of moduleLTE: present.

Price: from 12.5 thousand rubles

SonyXperiaZ4v- a wonderful device from the famous Japanese company, which, alas, was not sold in Russian showrooms and stores. In the USA, his time was also short: finalizing the gadget Z4 to model Z4v took so long that Sony managed to announce Z5, who, of course, “pulled the blanket” over himself. Nevertheless, XperiaZ4v remained in the history of mobile technology as the first smartphone with QuadHD-screen.

SonyXperiaZ4v, like SamsungGalaxyS7, is equipped with 2 wireless charging standards: standard Qi and alternative Powermat. Because of this, by the way, the body of the device turned out to be quite thick. Also Z4v has a fast charging function QualcommQuickCharge 2.0– thanks to it, in 45 minutes the gadget can be charged so much that the battery lasts for the whole day.

Advantages

• Supports two wireless charging standards at once Qi And Powermat.
• Display QuadHD– the first in the history of mobile technology.
• Two excellent cameras: a rear one with a resolution of 20.7 megapixels (with LED flash) and a front one with a resolution of 5.1 megapixels.
• Standard protected housing IP65 And IP68.
• Powerful modern processor with 8 cores.

Flaws

• “Extra weight” of the device, caused by the fact that too much is installed inside the case.
• Overheating of the gadget that occurs when using heavy applications and games.

Microsoft Lumia 950

• Battery capacity: 3000 mAh.
• Wireless charging standard: Qi.
• Display size and matrix: 5.2 inches, AMOLED matrix.
• Processor and graphics: 6-core Qualcomm Snapdragon 808 + Adreno
• Availability of moduleLTE: present.

Price: from 18 thousand rubles

MicrosoftLumia 950 became the first gadget released since WindowsMobile 10, and, unfortunately, the last flagship produced by Bill Gates' company. Both in the opinion of users and from the point of view of mobile experts, the smartphone turned out to be a feast for the eyes. Availability of wireless charging module Qi gets lost among a lot of other, more innovative features.

Present biometric identification– you can unlock the device using an iris scanner. This feature of the device is unique. Screen resolution QuadHD boasts a record dot density of 564 ppi. The rear camera is equipped with a 6-lens module from a world famous company ZEISS. In addition, there is a fast charging option QuickCharge from Qualcomm With its help, you can fill a dead battery up to 50% in just half an hour.

The main disadvantage MicrosoftLumia 950 Previously they thought the price was quite high, but now the cost of the gadget is more than moderate - especially for such rich functionality. Microsoft loudly “slammed the door”, releasing one of the brightest devices of 2016.

Advantages

Flaws

• Ascetic appearance (this problem is again solved by replacing the lid).
• High cost for a device under a brand that does not have much weight in the mobile market.

YotaPhone 2

• Battery capacity: 2500 mAh.
• Wireless charging standard: Qi.
• Display size and matrix: 5 inches, AMOLED matrix.
• Processor and graphics: Quad-core Qualcomm Snapdragon 800 + Adreno
• Availability of moduleLTE: present.

Price: from 6.7 thousand rubles

In our selection there was also a place for one of the best Russian smartphones. We're talking about YotaPhone 2– a gadget that made a splash at the exhibition MWC 2014. The main feature of the smartphone from Yota– the presence of two displays: the main color and additional, made using technology E-ink. Probably only the lazy have not heard of this innovation in Russia. But about the fact that YotaPhone 2 It’s also compatible with wireless charging, few people know.

Company Yota is a member of the Consortium WPC, who developed the standard Qi- accordingly, and YotaPhone 2 can be recharged according to this standard.

Allow yourself now to purchase an innovative gadget from Yota maybe even a Russian with a very average income: compared to the start of sales, the price of a smartphone has dropped more than 5 times - from 39 thousand rubles to 6.7 thousand rubles! Despite the futuristic original design and good functionality, the gadget did not win fans either abroad or in Russia.

Advantages

• Having two screens saves battery power.
• Oleophobic coating of the main display - thanks to this coating, there are no fingerprints left on the screen.
• Supports wireless charging as standard Qi.
• Minimum price.
• High performance for low price.
• Origin – the user can boast that he has a Russian smartphone in his hands.

Flaws

• It is difficult to find original accessories.
• Weak 8 megapixel rear camera – even on the first one Yota were 13 megapixels.
• The front camera is also not happy with the resolution - only 2 megapixels.
• Unreliable grip of the gadget body with the palm.

What other phones support wireless charging?

If this is your first time hearing about wireless charging technology, we strongly recommend that you read the material here.

From the world by thread

So, at MWC 2013 (Mobile World Congress, for that matter), the presentation of wireless charging looked somewhat generalized compared to the previous year. And it seems that we have all already seen this.

Let’s remember that in 2012, Duracell dedicated a separate stand to wireless charging, showing entire sets of devices for no more than $130 (price in the USA). Among the new products, the company also introduced the Wireless Charging Card - a special insert that could be placed under the cover of almost every mobile device without harming the strength of the case. With a thickness of less than 1 mm, the liner does not lead to the formation of backlashes or loose contact of the cover with the body of the smartphone. The Wireless Charging Card today has many analogues, and this development was not the first of its kind.

In addition to Duracell, the wireless charging stand was also prepared by the Wireless Power Consortium Association, which, by the way, came up with the idea of ​​​​standardizing wireless charging technology (later called Qi, read as “qi”). The WPC includes dozens of the largest companies from around the world. Offhand, among others there are Energizer, Samsung, LG, Philips, Nokia, Sony and, more recently, the same Duracell. In addition to Qi, the Association earned another big plus in its karma by making all its certified products compatible. Those. The Qi charger from Nokia can charge not only its own smartphones of this brand, but also any other gadget that meets the generally accepted standard. And if suddenly you carry a smartphone with a Duracell insert in your pocket, you can also charge your mobile phone on any of the Qi-supporting bases.

This year there was only one stand. Developments have not gone far technologically, but a couple of innovations have nevertheless appeared: firstly, in 2012 it was possible to charge mobile communication devices using Qi and only because... the maximum power of 5 watts was enough for this. The 35-watt charging prototype, also presented at the World Congress, did not look very confident, so consultants immediately hinted that the device was still at the development stage. At the current MWC, devices with a power of up to 120 watts have already been presented, which is enough to charge tablets.

The inductive charging principle has not yet allowed manufacturers to change the shape of the dispensing and receiving parts of the device. Wireless charging is essentially two coils - distributing and receiving - between which a magnetic field arises. Often we don’t see the simple internal structure of the charger, but some manufacturers have managed to beat it. Thus, the ring-shaped PowerKiss adapters caused particular joy, thanks to which you can even charge phones without a built-in Qi module.

PowerKiss, due to the release of several modifications of the USB connector, can be connected to absolutely any phone or smartphone, lay the gadget flat on the station and enjoy wireless charging. They are produced in different colors, which can also add to the useful characteristics of the device.

At MWC 2013, PowerKiss was shown again, and with it some very smart solutions for adapting the transmitter. They propose to make it not in the form of a separate object, but, for example, to discreetly adapt it to a specific interior: instead of the usual mat or stand, the base can be located in the arm of your sofa, or in the lid of a multimedia center or speakers.

The latter option has already been embodied in TDK products: the Wireless Charging Speaker Q35 looks stylish, and, in addition to its intended purpose, it also charges your cell phones.

Price issue

Unfortunately, we did not get our hands on any of the listed devices, so we will limit ourselves only to general specifications and, in fact, price tags.

Devices that support wireless charging technology can be divided into two categories. Those in which this feature is included by the manufacturer are called “Qi Integrated”. Phones that support Qi out of the box will be slightly larger than others. But you don’t have to glue inserts under the cover or connect any other parts built into the case. You will need to buy a distribution base and that’s basically all.

The “Qi Ready” category includes devices that are Qi-ready, but require a technological upgrade to ensure full operation of the technology. In this case, both the transmitter and the receiver will appear on the shopping list.

True, you most likely will not see either the first or second designation on the device box. Manufacturers often simply limit themselves to mentioning the ability to connect a smartphone or tablet to Qi. You can only find out which phone you got by opening the package. Or, say, from detailed reviews of this model.

See the table of phones that support Qi below. Compatible models released as of early 2013 are shown here.

On sale, as you might have guessed, you can find both a Qi-charging kit and a base and receiver separately. For example, the Philips DLP7210B kit is a case for the rear panel of the device with an energy-receiving coil, as well as a base for transmitting charge. The Qi charging kit for the Samsung Galaxy S4 is made using a similar principle.

Production subtleties

With Qi, the charger market has expanded significantly. Judge for yourself: if earlier we were somehow not very picky about the design of adapters, now we have the right to turn our noses a little. The consumer chooses the device based on its shape, color, and how it is attached to the phone. At the same time, not limiting ourselves to the offers of only one brand that has released a consumer-owned gadget.

Perhaps the simplest option is to place a receiver chip under the device’s body if your smartphone or tablet did not initially receive one. Firstly, this will not affect the external condition of the phone: it will still be hidden under the cover! And secondly, it will not significantly affect the weight of the gadget.

The cost of the receiver plate is low: for example, a plate that is universal for all Samsung smartphones can be purchased starting from $11. The complete set (base and receiver) will cost about $62.

Another “inconspicuous” option for connecting your phone to Qi is a replaceable back cover with a built-in receiver. Such, as we have already said, are also in the catalogs of Nokia, Philips and Samsung.

The advantage of the back cover with a Qi receiver is that, although it somewhat thickens the body of the device, it also serves to protect the gadget. Such gadgets do not have armor-piercing properties, but, in theory, the phone will be more intact.

A branded cover for Nokia Lumia phones will cost about $27. Note that the manufacturer produces them in several colors.

Another form of receiver is one that connects via the PowerKiss USB port. This one costs about $34/piece. (in the USA). This project is interesting in that it is aimed, rather, not at individual use, but at mass use: furniture with built-in Qi bases, as well as PowerKiss rings scattered on the surface, may soon appear in airports, waiting rooms at train stations, cafes, libraries and other public places where such an innovation will deservedly receive national gratitude.

PowerKiss, by the way, solves the problem of connecting smartphones to Qi bases that, although they have a non-removable back cover, did not receive the corresponding wireless charging module during production. Removable panels with a Qi module can still be attached to such smartphones. But when purchasing a kit, you need to carefully read the device specifications: not all receivers are capable of efficiently transmitting energy through the lid. And PowerKiss provides direct communication with the device’s battery, so you’ll have a better chance of charging the battery faster with just such a “ring.”

Speaking of efficiency. The efficiency of most wireless chargers is no more than 80%. This does not mean that your phone will lack something, it’s just that the technology is still imperfect and you need to carefully follow the instructions in the operating instructions to increase the level of Qi performance in each specific case.

Rarely, but sometimes particularly honest manufacturers admit that their device will not be able to work to its maximum, no matter how hard you try. For example, the description of METRANS Wireless Transmitting Terminal MWT02 clearly states: the maximum operating efficiency is 73%. At a price of almost $78, this is a quite frank warning.

If Qi, as seen in the example of PowerKiss, is just being planned to be integrated into the interior, particularly enterprising owners of wireless chargers manage to independently place charging bases under the covers of bedside tables or coffee tables. The following video clearly shows how easily the latest technologies lend themselves to such creative experiments.

Now a little about the forms of distribution bases.

The most common option: a pad-shaped base, i.e. stands.

Let us remind you that in order to wirelessly charge the gadget, it must be closely adjacent to the base. The maximum distance by which the device can be raised today for continuous energy transfer is only 4 cm!

Below you can watch a test of the Qi system from Nokia a la “charging with obstacles”.

The horizontal position of the smartphone, on the one hand, is as convenient as possible for a typical scenario: you come and throw the phone on the table. On the other hand, it is much more convenient to use a smartphone while charging if the same platform has a certain lifting angle: not enough for the smartphone to slide off, but making it easier to work with the device if it is suddenly needed.

Strictly horizontal bases can be found in the catalogs:

• Zens (charger for one smartphone costs $65);
• Energizer (the Dual Inductive Charger base allows you to charge up to three devices: two via Qi, and the third via a standard USB port; the model’s body is slightly inclined, which is much better for the office charging option than the flat version; it costs $89);
• Duracell (the silver Powermat pad costs $34 and is designed to charge one smartphone; it has a nice square shape with rounded edges);
• Nokia (DT-900 base is no larger in size than a computer mouse; suitable not only for Nokia phones; price $47).

Another “flat”, but non-standard option is presented by TDK: the Q35 Qi Wireless Charging Speaker costs $199 and is a speaker placed in a modern cubic case, on the top edge of which, in fact, the distribution coil is mounted.