On the forum, you can often see this statement. Because the number of charges and discharges is limited, you should use up the battery of your mobile phone as much as possible to recharge it. However, we found an experimental table on the charging and discharging cycles of lithium ion batteries. The data on cycle life are listed as follows:

Cycle life (10% DOD):>1000 times

Cycle life (100% DOD):>200 times

DOD is the abbreviation of discharge depth. It can be seen from the table that the number of rechargeable times is related to the discharge depth, and the cycle life at 10% DOD is much longer than that at 100% DOD. Of course, if the relative total capacity of the actual charge is 10% * 1000=100100% * 200=200, the full charge and discharge of the latter is better. Under normal circumstances, you should charge the battery according to the principle of recharging after the remaining battery power is used up. However, if the battery is not expected to last for the whole day on the second day, you should start charging in time. Of course, if you are willing to carry the charger to the office, that's another matter. When charging is needed to cope with an important event that is expected to lead to busy communication, even when the battery has a lot of residual power, you should only charge in advance, because you have not really lost "1" charging cycle life, that is, "0. x" times, and often this x is very small. The principle of recharging the remaining battery power is not to make you go to extremes. As a popular saying like long charging, it is "try to use up the battery power of the mobile phone, and it is better to use automatic shutdown". In fact, this practice is only on nickel batteries, in order to avoid memory effects. Unfortunately, it has also spread in lithium batteries. There was an example where someone used to automatically shut down the phone after the warning that the battery level of the phone was too low, but they still did not charge. As a result, the mobile phone in this example did not respond during the subsequent charging and startup, and had to be sent to the customer service for maintenance. In fact, this is because the voltage of the battery is too low due to excessive discharge, so that the battery does not have normal charging and starting conditions.