The development of lithium battery technology has not yet solved the problem of mobile phone battery capacity. However, we can "save the country" by "curving the curve". When the charging time becomes very short, is it equivalent to increasing the battery life of the mobile phone? This brings us to today’s topic – fast charging.

　　I was on a business trip some time ago and I kept playing games on my phone. When my phone was almost out of battery, I realized that I had forgotten to bring a power bank. I had to take out my laptop to charge my phone. At this time, if my phone could be fully charged quickly, I would be happy. It’s time to play games. However, the reality is always cruel. Using a computer to charge a mobile phone in an emergency is simply unreliable. Friends, have you noticed that today's smartphones are getting higher and higher in configuration, but the development of lithium battery technology has not yet solved the problem of mobile phone battery capacity. However, we can "save the country through curves" when the charging time becomes very short. , is it equivalent to improving the battery life of the mobile phone? This brings us to today's topic - fast charging.

　　According to the calculation formula, power is equal to voltage times current, so current fast charging technology is nothing more than increasing the voltage or increasing the current.

　　The current solutions for increasing voltage mainly include Qualcomm QC technology and MediaTek's PE technology. The principle of increasing voltage is very simple. For example, the maximum carrying current of a USB port is 1A. When the charger output is 5V, the charging power is 5W; if the voltage is increased to 20V, the current is still 1A, the charging power is 20W, and the charging time is reduced to a quarter. One, of course this is an ideal situation without considering losses. Currently, both QC3.0 and PE+ technologies can increase the voltage to 12V and adjust the current accordingly to achieve fast charging.

　　Of course, supporting QC and PE technology will definitely require the support of new chips from Qualcomm and MediaTek. So if I am using an old mobile phone and its chip does not support QC or PE, will it be impossible to accelerate charging? So there is a second method here, which is to increase the current.

　　So can we change the charging speed by replacing the high-current charging head? We have prepared three charging heads of 1A, 1.5A and 2.1A for charging to see what the charging current is. We chose older mobile phones that do not support fast charging technology as test objects. The actual charging current of the 1A charging head is 0.76A, the actual charging current of the 1.5A charging head is 0.95A, and the actual charging current of the 2.1A charging head is 1.6A.

　　Because the charging head usually provided with mobile phones is about 1A. Therefore, when replacing the charging head with a higher current, the charging speed will increase accordingly. However, because mobile phones using USB interfaces are limited by the USB2.0 standard, the charging current will be limited to less than 1.5A. The maximum current allowed by the interface is 1.8A, so even if you use a 2.1A charging head, the current will be limited. . It is precisely in this way that some domestic manufacturers have made improvements based on this point. It maintains the inherent 5V charging voltage of USB charging, increases the charging current, and exceeds the 1.5A limit of the USB interface, so that the charging current can reach about 4A. This can also greatly increase the charging speed and achieve fast charging.

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