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You need to know these wireless chargers Apr 18, 2018

For wireless charging, our expectations are of course not bound by charging anywhere in the free space. Of course, the ideal is very full, the reality is very skinny. Compared with the wired charging technology, wireless charging does not have many advantages. In addition to the convenience of using the charging cable, the charging speed cannot be compared with the wired charging. It is not comparable to the needs of some users for using mobile phones while charging.


However, for some users, wireless charging is now available. In some scenarios where mobile phones are not frequently used, wireless charging can be used to its advantage.



Wireless charging technology


The core principle of wireless charging is based on electromagnetic induction, and the principle is not complicated. At present, there are two main technical branches in the industry, one is the magnetic field induction technology represented by the Qi standard, and the other is the magnetic resonance technology represented by the AirFuel standard.


In principle, magnetic resonance is a better solution. It supports farther charging distances and can support simultaneous charging of multiple devices. However, magnetic resonance technology is not yet mature, and through the stacking of multiple coils, the use of Qi's standard wireless charger can also enable multiple devices to be charged at the same time.


However, magnetic resonance is still the future direction of wireless charging. Qi also incorporated magnetic resonance technology into its standards. It can be seen that near-distance power transmission is not unachievable.


Wireless charging devices on the market

Currently, the standard wireless charging used by smartphones and consumer-grade wireless chargers in the market is Qi. Therefore, as long as the mobile phone supports Qi wireless charging, theoretically all wireless chargers using the Qi standard are compatible (including special hard-to-serve iPhone).


However, different mobile phones and wireless chargers are actually different in charging efficiency. For wireless chargers, generally only the input and output powers are listed, but for mobile phones, the received power is the key indicator for determining the charging efficiency. That said, the received power is about 75% of the output power.


Charging board side


At present, the mainstream wireless charger is mainly used by Qi's Basic Power Profile configuration, supports 10W output, and the conversion rate is equivalent to about 5W to 7.5W of received power.


However, wireless chargers that use the Extended Power Profile configuration standard have been born one after another this year and can support up to 15W of output power, which is equivalent to about 10W of received power, which can greatly improve the wireless charging speed of mobile phones.


Mobile terminal


Since the wireless charging board has power limitations, the phone is naturally the same. Current mainstream smart phones (mostly using Basic Power Profile configuration) support wireless chargers with 5 to 10W output power.


For example, Samsung Galaxy S series phones can support 10W wireless charging, while Apple iPhone 8/8 Plus and iPhone X can support 7.5W wireless charging, of course, converted into receive power will be lower.


In addition, smartphones supporting the relatively fast wireless standard Extended Power Profile are also being introduced this year. Currently, there are familiar Sony XZ2 series and LG V30 series. The received power can reach about 10W, but it needs to be configured with the same support for Extended Power Profile. Wireless charger.


In summary, different mobile phones need to match different specifications of wireless chargers, but for most mobile phones, wireless chargers that support 10W output are sufficient. In addition, many wireless chargers do not necessarily come with charging heads and data cables. They need to be selected according to their input power and fast charging standards.


Although the iPhone 8/8 Plus and iPhone X are compatible with the Qi standard, not all Qi wireless chargers can be used to make it 7.5W fast, as you can see in this article: "Mfi must be watched! Talk to you about Apple's wireless charging


In addition to power also need to pay attention to?

FOD foreign body detection


Foreign object detection of the FOD should be the basic safety function of the wireless charger. When a metal foreign object is sandwiched between the mobile phone and the wireless charger, the wireless charger can sense and cut off power to prevent overheating of the metal foreign object.


However, the FOD function can't be judged by viewing the publicity parameters. Only through actual measurement, we can see the specific performance. Most of the wireless chargers in the market are qualified for FOD foreign body detection.


cooling problem


The output power of wireless chargers is not constant, and the peak power is mainly determined by the design materials and cooling methods of wireless chargers. We recommend to purchase models equipped with active cooling fans. Although thick, the output of peak power is generally The time is longer.


Charging distance


Qi wireless charger's maximum charging distance is about 10mm, so every other protective case can also be charged, do not need to "delight" the phone to charge.


With the development of the Qi standard, the cost of wireless charging technology has slowly been reduced, with more and more products of about 100 yuan, and the cost of experience is considered to be low. At present, millet Huawei has begun to try to add wireless charging for its products. It can be expected that the wireless charging function will have greater popularity in the next two years.