Mobile phones are charging faster and faster, but are their safety and battery life guaranteed?

It used to take several hours to fully charge a mobile phone, but now it can be done in a few minutes. While faster and faster charging technology makes people's lives more convenient, it also raises some concerns, such as whether the safety of fast charging technology is really guaranteed; whether the battery life of mobile phones equipped with fast charging technology will be shortened, etc.

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Is fast charging safe?

In the smartphone market, faster and faster charging speeds are constantly breaking people's imagination. Various mobile phone manufacturers continue to increase the charging power of mobile phones to shorten the charging time of mobile phones.

China Business News reporter found that the current fast charging power of mobile phones has reached 200 watts. In June this year, Xiaomi announced that the modified version of Xiaomi 11 Pro is equipped with 200-watt wired charging and 120-watt wireless charging technology, of which wired charging can charge 100% in 8 minutes and wireless charging can charge 100% in 15 minutes.

Many mobile phone manufacturers have also entered the 120-watt era. In July last year, iQOO announced that its 120-watt ultra-fast flash charging technology had entered mass production, charging 50% in 5 minutes and 100% in 15 minutes. It was also installed in the iQOO 5 series released in August last year. OPPO also released its 125-watt fast charging technology in July last year.

According to incomplete statistics from a reporter from China Business News, the fast charging power of most mobile phones on the market is between 44 watts and 67 watts. Some mobile phones (such as Honor 50 Pro) support 100-watt fast charging, while Xiaomi MIX4, Redmi Note 11 Pro series, iQOO8 series, etc. support 120-watt fast charging.

How to ensure the safety of battery use

"At present, all mobile phone manufacturers meet domestic standards and specifications in fast charging technology, and have protection mechanisms during charging to ensure the safety of fast charging." Zhang Xing, a researcher at China Research and Development Institute, told China Business News.

Pan Yanlin, deputy chief engineer of the Shanghai Space Power Source Research Institute, told China Business News that if lithium batteries can meet the requirements of fast charging, then the active materials, electrode preparation, and selection of diaphragms and electrolytes of the battery itself must be specially designed. At present, the research and development of fast-charging batteries is very good, so if the battery itself supports fast charging, it should have been verified by the manufacturer in large quantities, and there will be no safety problems if it is charged with the original charger. "But if the mobile phone battery does not have the fast-charging feature, but is charged with a fast-charging charger, there are still certain safety issues." Pan Yanlin said.

"One disadvantage of fast charging is the heat dissipation problem. Fast charging can cause local overheating of the battery, but now some new heat dissipation materials such as graphene are used to ensure its safety. In addition, rapid impact and mechanical collision can also cause battery bulging and explosion, but these are isolated incidents, and current smartphones have built-in safety detection systems." Fang Tianxiang, manager of Beijing Yanjing Bizhi Information Consulting Co., Ltd., told China Business News.

"The improvement of charging safety mainly includes three aspects: improving conversion efficiency through new materials, monitoring battery safety through built-in power management chips, and increasing safety protection by using new technologies and structured designs," said Fang Tianxiang.

Why is charging getting faster and faster?

Zhang Xing said that the current mobile phone fast charging technology achieves the purpose of fast charging by increasing the charging power and shortening the charging time. The method of increasing power is generally to increase the voltage or current, so the existing fast charging technology is mainly divided into two categories: low-voltage and high-current fast charging, and high-voltage fast charging.

"Major mobile phone manufacturers have launched their own fast charging technology. The principle is to achieve high-power charging by increasing the charging current and voltage. Simply put, the input power of the charging port is equal to the input voltage multiplied by the input current. Generally, mobile phone chargers will have a charging curve, which achieves the highest charging efficiency by controlling different voltages and currents." Zhang Xing said.

"Generally speaking, the most efficient method starts with constant current charging (faster charging), then constant voltage charging (the charging speed is reduced because the voltage of the battery itself has increased), and finally trickle charging (after full charging, to compensate for the capacity loss caused by self-discharge)." Zhang Xing said.

"Mobile phone battery fast charging is related to the power adapter, charging cable, fast charging chip and battery, and the requirements for fast charging chip and battery are very high." Fang Tianxiang said, "Fast charging technology will be upgraded from the initial improvement of power adapter to battery technology in the future."

Will the battery life be shortened?

While safety is guaranteed, most people are still concerned about the battery life under fast charging. Will fast charging shorten the battery life?

Zhang Xing said that when charging a smartphone, the charging current is not constant. When the phone is at a low power level, the built-in power management chip will send a signal to the charger, and the charger will speed up the charging of the phone. When the phone has 60% to 80% power (the setting range varies for different brands of mobile phones), the built-in chip will send a signal to the charger to slow down the charging speed, thereby reducing battery loss, protecting the battery, and reducing heat.

"When using fast charging to charge a mobile phone, the battery will be in a high current state for a long period of time to replenish the phone's power, so compared to ordinary charging, fast charging will theoretically cause more damage to the battery. But this damage will not affect our normal use, nor will it cause the lithium battery life to fail to meet usage expectations." Zhang Xing said.

"From the working principle of the battery, the life of fast charging will definitely be shorter than that of normal charging. According to the experiments conducted so far, the cycle life of lithium-ion batteries is related to the charging rate (i.e. the measurement of charging speed). At a reasonable charging rate, the battery life will be very long; but if an unreasonable charging rate is used, such as high current charging, the battery life will also be reduced very quickly." Pan Yanlin said, "However, mobile phones are also consumables and need to be replaced every two or three years. Manufacturers use fast charging based on this consideration. The life of a general battery is about 600 cycles, which is two to three years. The complete process of fully charging the battery and then discharging it is one cycle, but in daily life we ​​often charge it before the battery is used up. In this case, the battery life will be longer."

"Battery life is related to the number of times the battery is charged, and is most closely related to the battery's charge and discharge cycles. Fast charging has little effect on battery life," Fang Tianxiang said. "In addition, some mobile phones, such as Apple and Huawei, have battery health systems that can check the battery life."

At the same time, regarding the precautions for charging mobile phones, Pan Yanlin said that you should try to use the original charger of the mobile phone, because the original charger will have some adaptive configurations for the overall function of the battery. In addition, if the performance of the mobile phone battery decays after one or two years of use, try to replace it with the original battery.

At the same time, Zhang Xing also said that you should not play with your mobile phone while charging it, and you should charge it in a suitable environment to avoid overcharging.