18650 lithium battery.There is no breakthrough in lithium battery technology yet. Are various standards of fast charging compatible?

　　In an environment where there has been no major breakthrough in lithium battery technology and new energy batteries have not yet been applied to electronic products, battery life issues have always troubled the majority of mobile phone users. The emergence of fast charging technology allows users to use fragmented time to charge more power into their mobile phones. The battery life problem can be solved from another aspect. However, many netizens still mistakenly believe that fast charging chargers are interoperable. Today, the author brings you two experiments: 1. To verify the compatibility of fast-charging mobile phones/charging heads; 2. The speed performance of non-original chargers for charging iPhone 6s.

　　Popularization of charging knowledge

　　1. The output voltage/current on the charger is only the maximum allowable value, not the actual output value. The actual output value depends on the specific needs of the mobile phone/mobile device.

　　2. Charging first goes through the ① constant current stage. At this time, the actual voltage of the battery is lower than the charging voltage (mostly 4.3v). During the constant current charging process, the battery voltage increases. When it increases to about 4.3v (the battery is approximately 85% full), Enter ② constant voltage mode, the charging current gradually decreases, charging is about to be completed, and then enter ③ trickle charging mode to charge with pulse current to extend the battery life.

　　3. The larger the battery capacity, the greater the charging current it can withstand, which is what we often call charging 0.5c, 1c. For example, a 3000mAh0.5c (rechargeable) battery can withstand a charging current of 1500ma, which means it can withstand a current of 1.5a. With technological innovation, the charging current value that lithium batteries can withstand is now increasing, which greatly shortens the charging time in the constant current stage.

　　4. The voltage output by the charging head will not be directly loaded to the battery level. There will also be a secondary voltage reduction electrode inside the mobile phone. Therefore, the high-voltage 9v and 12v fast charging are only to increase the charging power, reduce heat loss during transmission and avoid reaching the upper limit of the microUSB port current. It does not mean that 9v and 12v are directly loaded on the two poles of the battery.

　　Experiment 1: Charging speed of iPhone 6s with different charging heads

　　Many people may remember that when their iPhone is charged using some third-party charging heads or data cables, the phone will prompt "This cable or accessory has not been certified, and the charging current will also be limited, which greatly increases the charging time." It takes time. But now, even if we use a non-original charging head, it seems that we rarely see the message "This cable or accessory has not been certified yet." So the question is, even if there is no relevant prompt now, will the charging speed be affected by using non-original charging heads and original charging heads to charge the iPhone? Below we verify it through experiments.

　　Testing session:

　　Test mobile phone: iPhone6s (Hong Kong version, iOS9.3.1), charging head: original iPhone, plugboard with USB port, third-party charging head.

　　Test method: Use a USB voltage/current detector for real-time monitoring of charging, and monitor the voltage/current values at 10%, 50%, and 95% for 6 seconds (the specific power level has a slight deviation). (The same mobile phone has a certain demand for input voltage/current at the same remaining power, so as long as the voltage/current values read at three times are similar (the power is basically the same), it can be considered that the overall charging time is not much different. )

　　Test Data

　　The test results show that during the two periods of the test (fast charging stage/trickle charging stage), the output power of a third-party charger is basically the same as that of the original iPhone charger. At this time, the charging speed is equivalent, while the plug-in board with USB output is not. When the output voltage is relatively large, the output power is also ahead of the other two. Therefore, the charging speed ranking (estimate) is: socket with USB > iPhone original charger = third-party charger (from fast to slow). Of course, different third-party chargers/sockets with USB have different output effects.

　　The author used 5 original chargers from different brands + 2 plug-in boards with USB output for testing (the phone was 50% charged) and found that the output voltage was basically slightly greater than 5v (some with higher line compensation can reach 5.3v. And if there is no line compensation, it is lower than 5v), and the current is also about 1a. Therefore, using some non-original charging heads to charge the iPhone will indeed be faster than the original charging heads. Of course, counterfeit/low-quality chargers are another story.

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