Charge in time to prevent over discharge. Ordinary mobile phone users are not aware of the harm of over release, because there are usually no reports of safety accidents. Moreover, some people even think that regular deep discharge is good for the maintenance of battery performance. In fact, it is not, because the memory effect of lithium battery is negligible, and there is no saying that deep discharge eliminates the memory effect. Theoretically, the total cycle life of lithium battery with deep discharge will be greater, but the risk is that excessive discharge of the battery will lead to low battery voltage and can not be charged normally. Sometimes it will take a long time to start up, or even fail to start up. The lesser of the two evils is the right. A shorter service life is better than not being able to use it. Therefore, we advise the majority of mobile phone and laptop users not to often use the black screen.