This problem is closely related to the battery activation problem above. For the time being, the battery is set to the user's hand to have electrode passivation. In order to activate the battery, perform deep charge and deep discharge cycles for 3 times. In fact, this problem is converted into deep charge. The question of 12 hours of charging. Then my other article "On the charging time of mobile phone batteries" has already answered this question.

　　The answer is that you don’t need to charge for 12 hours. In the early days of mobile phone Ni-MH batteries needed replenishment and trickle charging process, it may take about 5 hours to reach the most perfect full charge state, but it does not require 12 hours. And lithium The constant current and constant voltage charging characteristics of ion batteries determine that its deep charging time does not need to be 12 hours. For lithium ion batteries, some people may ask, since the current of lithium ion batteries in the constant voltage stage is gradually reduced, is it when the current is small? The real deep charge is when infinitely small. I once drew the curve of the current reduction in the constant voltage stage against time, and performed multiple curve fittings on it, and found that this curve can be close to zero current by a function of 1/x. In the actual test, due to the self-discharge phenomenon of the lithium-ion battery itself, this zero current can never be reached. Take a 600mah battery as an example, set the cut-off current to 0.01c (that is, 6ma), and its 1c charging time does not exceed 150 Minutes, then set the cut-off current to 0.001c (that is, 0.6ma), and its charging time may be 10 hours --- because of the accuracy of the instrument, it has not been accurately obtained, but the capacity obtained from 0.01c to 0.001c has been calculated It is only 1.7mah, and it is meaningless to exchange more than 7 hours for this less than three-thousandths of a capacity. Besides, there are other charging methods, such as pulse charging to make lithium-ion batteries. Reaching the 4.2v limit voltage, it does not cut off the minimum current judgment stage at all. Generally, it is 100% full after 150 minutes. Many mobile phones use pulse charging. Someone once used the mobile phone to display the full charge before using the seat The test method is not rigorous. First, the green light displayed on the charger is not a basis for detecting whether the phone is fully charged or not.

　　The only final way to detect whether a lithium-ion battery is fully charged or not is to test the voltage of the lithium-ion battery when it is not charging (nor discharging). The so-called constant voltage phase current reduction is the real purpose of gradually reducing the battery. The additional voltage generated by the charging current on the resistance, when the current is as small as 0.01c, such as 6ma, this current multiplied by the battery internal resistance (generally within 200 milliohms) is only 1mv, and it can be considered that the voltage at this time is no current The battery voltage of the state. Secondly, the reference voltage of the mobile phone is not necessarily equal to the reference voltage of the cradle charger.