Excessively high and too low state of charge adversely affect the life of the lithium battery. Most resellers that are sold on appliances or on batteries are re-charged based on 80% discharge. Experiments have shown that for some notebook lithium batteries, the battery voltage often exceeds the standard voltage of 0.1 volts, that is, from 4.1 volts to 4.2 volts, then the battery life will be halved, and then increased by 0.1 volts, the life is reduced to the original 1 /3; The more fully charged the battery, the greater the loss of the battery. A long-term low-power or no-power state will cause the internal resistance of the battery to move more and more, resulting in a smaller battery capacity. The lithium battery is preferably in the middle of the battery, so that the battery life is the longest.