Cellphone has been a part of our life, which is more acceptable in classroom. When smartphone become popular, its size and function have been improved all the time, but the battery can't last as long as its original situation. We need to charge smartphone when we see the warning of rest battery. Most people like to charge the phone before they sleep, then the next morning the 100% battery on screen makes them feel comfortable. But according to the latest study, a new research showed that full battery is not the most suitable situation for smartphone. It is best to maintain 60% to 70% battery, because full situation is a burden to the phone. So don't let your phone charge the whole night, or it will damage the long-term use of battery.