Analysis of the Heating Problem of Wireless Chargers

By the fall of this year, there will be more and more mobile phones with wireless charging functions on the market, and foreign Apple, Samsung, Google, Nokia, and domestic Huawei, Xiaomi, and Hammer are also joining. Although everyone adopts the qi standard of the WPC Alliance, they only provide qi certification of 5W power, that is to say, 5W wireless chargers can be used by anyone’s mobile phones, while 7.5W, 10W and 15W fast wireless chargers The charging is added with its own protocol (password), and they all use their own abacus.

Some phones that support wireless charging

However, judging from the current usage of consumers, there is a general problem of charging and heating. After the mobile phone is charged on the wireless charging stand for a period of time, the mobile phone will become very hot, even hot to the hand, and netizens are not happy, and they are instantly fried.

Netizens worry about wireless charging

So, if the temperature of the mobile phone really reaches 60 ℃, will it damage the battery? The answer is: there will be damage and shortened lifespan. We all know the characteristics of lithium-ion batteries. The operating temperature of lithium-ion batteries is generally 0-40 °C. If the battery is kept at a high temperature of 60 °C for a long time, the battery will be damaged.

However, why do some netizens report that their wireless chargers are not very hot and hot?

In fact, there are several fundamental reasons for the heating of wireless charging of mobile phones. After understanding the reasons, you can choose more suitable products and enjoy the fun of wireless charging with confidence:

1. The choice of method.

This is the most fundamental reason. Different methods have their own characteristics. For example, wireless charging methods such as NXP, IDT, Easy Charge, Xuxinsheng, etc., whether it is charging efficiency, mobile phone compatibility, or charging off, temperature control Other aspects are different. Some manufacturers will use some relatively cheap methods when considering the cost, abandoning some peripheral circuits and some functions, and getting what you pay for. This is why some products sell for several hundred yuan. Some are only a few dollars.

2. Temperature control circuit.

Generally, the wireless charging method will have a temperature control circuit and an NTC thermistor. This function is important to prevent the circuit from overheating during operation, burning components, etc., and can also control the appearance of power components. After too much heat, reduce the power, thereby reducing the temperature, this function is very important.

3. Selection of heating components.

The qi standard wireless charging originally used electromagnetic induction to generate current and drive the circuit to work. At the transmitting end, an LC oscillating circuit is formed by an inductor (coil), a resonant capacitor and a control chip. By oscillating in the frequency range of 110-205 kHz, a current will appear at the receiving end due to the changing magnetic field, so that the mobile phone can be charged. Therefore, if the appropriate components are not selected in the circuit, the error of each component will affect the overall performance, and excessive current consumption will cause excessive heat on the components.

4. The problem of the mobile phone

The battery protection temperature set by the systems of Apple, Samsung, Huawei, and Xiaomi are all different. During the operation of the mobile phone, the system detects the temperature from time to time. Once the temperature exceeds the set value, for example, it starts to reduce the CPU frequency, causing freezes. , or prompt a temperature alarm. The same is true for charging. For example, when the iPhone is charging wirelessly, when the temperature of the case is around 30°C, the system starts to reduce the power, and the Samsung mobile phone reduces the power at around 35°C (the parameters of the old and new models will vary). That’s why wireless charging with Samsung phones is slightly faster, but the phone feels a little warmer than Apple’s.

PhoneMust Wireless charger

Through the above analysis, everyone should know how to choose a suitable wireless charger. Although the current charging speed of wireless charging is not as fast as wired charging, it is still more convenient, especially for some business people, who use their mobile phones very frequently.