Photo: Anker
Is wireless charging a health hazard?
A tin foil hat and lead panties make up for all the negative ... sorry, kidding. Assurances about some dangerous radiation from wireless chargers can only be perceived with a condescending smile. As the saying goes, don't study physics and your life will be full of miracles (and / or unfounded fears). If at a distance of two centimeters above the surface of the station the phone stops charging and even recognizes wireless charging, then where does the radiation come from, which will “beat” for meters around, burning out the brain and the reproductive system?
Every second you are pierced by radio waves of cellular communications, Wi-Fi, Bluetooth, TV and radio broadcasting and many other signals in various ranges, you are exposed to an electromagnetic field from a computer, any electrical appliance and even electrical wiring in the walls, and a working microwave is like a "phonet" ! And all this has absolutely no effect on you, because it is not ionizing radiation (that is, not radiation).
Scientists have been studying the effect of non-ionizing radiation on humans for decades, and during this time it has been proven more than once that the only real danger to people is represented by long-term close embraces with powerful unshielded emitters, such as a military radar, a cellular base station aimed exactly at you at a distance a couple of meters or microwave without a door. And the harm will lie in the heating of water molecules in the cells and denaturation of proteins.
The only recommendation that at least somehow affects wireless chargers for smartphones is not to bring a working charger to the pacemaker. According to the instructions for medical devices, any extraneous powerful radiation is generally contraindicated. At the same time, there is no evidence or cases of the effect of Qi charging on the pacemaker. Moreover, wireless charging has already been developed for the pacemakers themselves.
Wireless charging cannot harm a person in any way. But for oneself - quite, if you leave a metal object between the phone and the station (like a coin in the photo). Electromagnetic induction is like that.
Photo: Wireless Power Consortium
However, if you set such a goal, using wireless charging can really harm your smartphone. The fact is that although Qi stations can detect foreign metal objects caught between the two coils, some thin objects, such as paper clips or decorative inserts on the case, can go unnoticed. Once over the transmitting induction coil, the metal will inevitably begin to heat up. A few minutes is enough for the same paperclip to heat up and start melting the plastic.
What kind of power adapter do you need for wireless charging?
The efficiency of wired charging is about 97%, that is, there is practically no energy loss. But the efficiency of wireless charging hovers around 60-75%. In theory, in spherical conditions in a vacuum, so to speak. In reality, the charging efficiency of the Qi standard is affected by the position of the phone on the charging station (that is, the position of the induction coils relative to each other), their characteristics and dimensions.
This year, tech news sites vied with each other to repost an enthusiast's “study” comparing the speed and power consumption of wired and wireless chargers. Naturally, the results were not in favor of the latter, and the efficiency of induction charging varied from station to station and depended especially strongly on the position of the smartphone on them. If we take the efficiency of wired charging for 100%, then the efficiency of Qi varied from 20% to 53%, and the original Google Pixel Stand showed the best result - 61%. True, the study was not devoted to the speed or heat dissipation of wireless chargers, but to their power consumption - the author led the reader to the conclusion that if at least half of the 3 billion smartphones in the world are charged over the air with such efficiency, power consumption and the load on the power grids will increase. On the one hand, you can't argue with mathematics. With another,The disappointing conclusion rests on the probability “if only, but if only”, and energy consumption in the world is already growing due to the digitalization of society.
, USB-, , . 1000 , USB- . !
: AliExpress
Based on the low real efficiency of induction charging, we come to the need to connect the charging station to a high-power power supply unit. If a 5-watt station is connected to a 5-watt charger, then due to losses, the charging speed of the smartphone will be ... most likely, none, because the resulting power on the smartphone's receiving coil will be slightly higher than the phone's power consumption in standby mode. Manufacturers of Qi-stations recommend using power supplies with a capacity 30-40% higher than that of Qi-charging. So, Apple recommends purchasing an adapter with a power of at least 20W for its new 15W MagSafe for iPhone 12. Fortunately, not necessarily made by Apple. We compared the charging speed of an iPhone 12 Pro via MagSafe when connected to an original Apple 20W adapter and a tinyAnker Nano for the same 20 watts. The difference between the two power supplies fits into an insignificant error - 188 minutes in the case of the Apple 20W charger and 190 minutes when paired with the Anker Nano 20W. And when charging from these power supplies not via MagSafe, but directly via the cable, the battery was charged in the same time of 104 minutes.
By the way, about MagSafe. Formally, all iPhones with a Qi receiver are compatible with the new Apple charging, but only the iPhone 12 family will charge with a maximum power of 15 watts, while the previous smartphone models will only charge 5 watts. Also, the reviewers noticed a strange incompatibility of MagSafe with powerful power supplies for MacBook - paired with a 96-watt MagSafe adapter "swung" only up to 10 watts... It is believed that the laptop adapter simply does not have the required power profile required for MagSafe.
Previously, we also advised purchasing power supplies for our wireless chargers about 40% more powerful, but now the most powerful Qi-stations, like the Anker PowerWave II Stand, we simply complete with a network adapter of the required power. If there was no cable included with your Qi charger, buy a guaranteed good wire - cheap unnamed USB cables often cannot transmit high currents, and even 0.5 A cannot be submitted to the lowest quality cables .
Is wireless smartphone charging dangerous?
We risk to surprise, but yes. As well as wired charging. And how dangerous for the battery is the absence of any charging and going into a deep discharge! Batteries generally die of life. The speed at which the inevitable end comes to an end is largely influenced only by the intensity of battery use. In a sense, lithium-ion batteries follow the covenant "live fast, die young" - the faster the battery runs out of charge / discharge cycles, the faster it will lose capacity and require replacement.
Note that we are talking about a resource expressed in the number of charge cycles. The battery itself absolutely does not care how they try to replenish the charge: through a wire or through an induction coil - the power controller will bring any incoming current to the desired characteristics and only then supply it to the battery.
But there is no smoke without fire, where did the urban legends about the dangers of wireless charging come from? There is some truth to this myth, just not where most ignorant smartphone owners believe. To repeat: the current supplied directly to the battery does not differ depending on the charging method, so there can be no "damage by induction currents" when using the Qi standard in principle. The battery is only damaged by heating to high temperatures, which accelerates the degradation of the anode and cathode and, as a result, leads to a decrease in capacity and, in particularly severe cases, even to a short circuit. Accelerated battery wear is observed when it heats up above 30 ° C , that is, the temperature threshold is mockingly small and below the temperature of the human body.
Let's count and figure. The efficiency of Qi-charging is about 60%, most of the lost energy is converted into heat, which heats up the coils and, accordingly, the smartphone, and with it the battery. An important point - for the highest efficiency, the coils in the station and the smartphone must be exactly one above the other, when they are displaced, the station is forced to increase the power, which causes increased heating.
Cheap unnamed Qi chargers will not spoil your smartphone, but they can spoil themselves - savings on the element base and poor-quality soldering can result in a short circuit. And it's good if there is no fire.
Photo: iphones_ru / Instagram
Smartphones can only cool naturally, so a solid case seriously impairs heat dissipation. This does not mean that it is imperative to get rid of covers in the name of battery safety - a new battery in a couple of years will cost less than a potentially broken screen now. But the cover still makes its contribution to the overheating of the smartphone.
Therefore, we do not recommend adding a wireless charging function to a smartphone using a Qi-receiver in the form of a thin plate with a plug. Smartphones without a Qi coil are simply not designed for induction currents to flow through them, and the induction coil begins to heat up the rear. At best, when using such a receiver, you will get very fast battery degradation due to overheating, at worst - damaged MEMS components, such as a compass or gyroscope.
Such Qi-receivers for smartphones can be purchased for 200-300 rubles, but imaginary convenience can result in damage to the battery and micromechanical components of the smartphone.
Photo: AliExpress
Still, the Qi wireless charging standard was not developed at random by Lazarus. It was proposed to protect the filling of smartphones with an insulating plate, the possible negative effects from overheating were calculated, and the power was limited to guaranteed safe values (the same 5 W in the first revisions of the standard, 15 W now).
Even in the worst case scenario, wireless charging won't turn your phone into a frying pan. Smartphones have a built-in thermal sensor that prevents the battery from heating above 45 ° C. If overheating is detected, for example due to a thick case that prevents the phone from cooling naturally, the power controller will need to reduce the power supplied.
But this is all about the original Qi specs with a basic 15W wireless charging power limit for smartphones. What about fast wireless chargers?
Is high power wireless charging dangerous or not?
Charging a modern smartphone from a 5W wireless station is a very meditative activity that only makes sense if you leave the phone on the bedside table all night. For those who naturally do not want to wait six hours, smartphone manufacturers offer their own proprietary fast chargers that work at full capacity only with certain devices of their own brand. So Huawei has SuperCharge for 27W and 50W, OPPO introduced AirVOOC for 65W, and Xiaomi announced 80W wireless charging in November 2020, capable of charging a 4000 mAh battery in 19 minutes.
Miracle of technology from Xiaomi - wireless phone charging in 18 minutes. What about the battery temperature? Not yet known.
Amazing power and, in theory, amazing heat dissipation. Note that when wired charging, gadgets also heat up, and this heating depends on the charging power (provided that the smartphone itself is not being used at that moment, otherwise the heating will be much higher). But with wireless transmission of energy, more heat is released. Accordingly, the 5 W Qi charger will heat up extremely insignificantly, 15 W more, but here is how the smartphone, which is powered through an 80-watt wireless station, should warm up ... In fact, we cannot yet answer this question for sure, Xiaomi's super-powerful charging has not yet entered the series, and no real independent tests have yet been carried out.
So, we have more or less figured out the heat dissipation of fast wireless chargers - in theory it is higher, but in practice the heating is controlled by temperature sensors and the separation of high power into two separate transmitting coils. But there is another possible negative factor that is common for both wired and wireless fast charging - increased current supplied to the battery.
Discharging and charging a lithium ion battery is the process of transferring positive lithium ions between the anode and cathode. The higher the charge or discharge power, the faster the ions leave one electrode and attach to the other. During the operation of the battery, the anode and cathode inevitably wear out, and fast charging slightly speeds up this process. How much? If you use an exclusively "fast" method, then the difference in capacity compared to a slowly charged battery will appear after two years or approximately 500-600 cycles, but with such wear and tear, in principle, it is reasonable to replace the battery, since it will inevitably lose 10-15% of its capacity. We emphasize that this problem manifests itself when using both wired and wireless high power chargers.
Why do some smartphones still have 5W wireless charging?
The Qi standard was immediately created open, so gadget manufacturers do not pay any royalties for installing a Qi induction coil. Accordingly, Qi support is just a matter of the cost of the induction module and redesigning the internals of the smartphone. Any company is free to decide whether to implement Qi support or not and the coil of what power to integrate.
In the world of products with a circulation of tens and hundreds of thousands (and those who are lucky with the demand - and millions) pieces, saving even a few cents is not superfluous. For example, in the iPhone X, the purchase cost of components for the implementation of wireless charging was $ 6. And this is at a mega-wholesale discount for a respected customer, and this is for a coil with a receiving power of no more than 7.5 watts. For a flagship for $ 1000, the extra $ 6 in the cost price of the weather does not do, which cannot be said about the entry-level and mid-level Android phones, whose manufacturers are not averse to saving money to increase competitiveness among equals.
The Palm Pre was ahead of its time as the first mainstream phone with wireless charging. And this is in 2009, a year before the appearance of Qi, two years before the first Android background with an optional Qi cover and six years before integrating Qi coils into smartphones.
Photo: HP
Fortunately, the price of the coils has dropped low enough that the installation of a receiver even at 10 W practically did not affect the price of the phone, although 3-4 years ago smartphones almost universally had only 5 W coils. In modern devices, a Qi receiver with a power of 5 W can be found only for two reasons: either you came across a device that is cheaper on all possible fronts, or this is a deliberate step to separate the company's smartphones into different price segments so that expensive models have more obvious advantages over cheap ones.
Come in, lie down, charge up
Cases of great importance should be approached lightly; cases of minor importance should be taken seriously. To get the most out of your smartphone's wireless charging module, you should choose a charging station, quality cable and charger wisely, rather than buying the cheapest things from the Chinese New Year sale. Put your smartphone on the station as evenly as possible, make sure that there are no metal inserts in the case (if any) and, most importantly, do not be afraid for your health and the health of the battery.