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How to choose a cost-effective wireless charger

If you want to say something that can change your life experience and improve your sense of happiness, wireless chargers must be included. After the iPhone 8 and iPhone X were released, more and more wireless chargers have been integrated into our daily lives in the past two years. Just saying that you don't need to sort out the messy charging cables, it makes people feel very comfortable. Now the three charging boards at home are also the most frequently used charging devices. One is a vertical type, one is a flat type, and the rightmost is a fast charge.


Differences in the principle of wireless charging


At this stage, the various wireless chargers on the market can be divided into four categories according to their wireless charging technology: electromagnetic induction, electromagnetic resonance, electric field coupling and radio waves. Among them, electromagnetic induction and electromagnetic resonance are mainly used for mobile phone charging.


Electromagnetic induction, most mobile phone wireless chargers currently use this technology. It is characterized by short transmission distance, relatively fixed use position, high energy efficiency, and simple technology. However, the magnetic field will rapidly weaken as the distance increases. If the distance is slightly larger, the energy utilization efficiency will be greatly reduced, because the energy will diverge in all directions. Represented by the Qi standard.


The electromagnetic resonance method has a certain tolerance relative to electromagnetic induction in distance, and can carry out wireless charging over longer distances. At the same time, it can also charge multiple devices, and there are no strict restrictions on the location of the charging device. However, the convenience of efficiency utilization will be relatively low. Magnetic resonance technology is not mature at present, but it is still the future development direction. Qi has also incorporated magnetic resonance technology into the standard.


How to choose a wireless charger


The first important thing is output power. Common ones are 5w, 10w, 15w, Apple's 7.5w, and Xiaomi's recent 20w. The greater the power, the faster the charging speed. For wireless chargers, the input and output power are generally listed, but the received power of the mobile phone is the key element that determines the charging efficiency. Generally, the received power is about 75% of the output power.


FOD foreign body detection. This is the most basic safety test of the charger. When there is a metal foreign object between the mobile phone and the charging board, the charging board will automatically cut off the power after detecting it to prevent the metal from overheating and causing danger. Most charging boards are qualified in this respect.


The number of coils is generally between 1 and 3 now. The coil mainly determines the charging range. Generally, the more coils, the larger the charging area, and the looser the position requirements for mobile phone charging. Most of the flat type is generally a coil, because lying flat, the mobile phone and the charging board have a very good fit, there is no need to add too many coils to increase the cost; the vertical charging board generally has two to three coils, which can be For the mobile phone to be placed horizontally or vertically without affecting the charging efficiency.


Heat treatment. Because wireless charging inevitably suffers from energy loss, electromagnetic waves cannot be fully utilized to charge the phone. At this time, the lost energy will turn into heat, and the temperature of the charging board will rise. If the temperature is too high, it will also cause problems such as shutdown of the phone. So now some charging boards have overheating protection. After the built-in sensor detects that the temperature is too high, the overheating protection system is automatically activated. However, overheating protection will inevitably affect the charging speed. Another solution is to add a fan, which will not affect the charging speed, but there may be some noise.


Charging distance. The maximum charging distance of Qi standard charging board is 10mm, so if there is a mobile phone case or other cover, it will not affect charging.


Adopt standards. Most of the wireless charging boards currently on the market adopt the Qi standard. As long as the mobile phone supports Qi wireless charging, theoretically all charging pads that use the Qi standard can be used. However, in addition to the more common Qi standard, there are some other standards that are not so common. You need to pay attention when buying, and don't make a mistake.


Lie down or upright. It is also very convenient to unlock the face while watching videos or replying to WeChat while charging. Moreover, it is not easy to be knocked off on the table, which is more stable than the lying-up type. And it looks neater and saves space. I prefer to use the vertical one during the day and the flat one at night. Because the flat type does not require too many coils, the price is cheaper.