Today I want to share with you the correct use of lithium batteries. When designing batteries, the cycle number is reached when the capacity decreases to 80% or below. Shallow charging and discharging result in shallow cycling, while deep charging and discharging result in deep cycling. The professional terms for charging depth and discharging depth are COG and dog. During the charging process of lithium batteries, the positive electrode material undergoes an oxidation reaction and loses electrons. The capacity of the negative electrode material for lithium ions is determined by the amount of positive electrode material. Overcharging can cause changes in the structure of the positive electrode material and can lead to violent chemical explosions due to the release of oxygen and electrolytes, or excessive reduction of the negative electrode material. Over-discharging can cause lithium to accumulate in the positive electrode stack, piercing the insulation membrane between the positive and negative electrodes and causing internal short circuits, thermal runaway risks, irreversible damage to the positive and negative active materials, and permanent capacity loss. Therefore, overcharging and over-discharging can not only affect the battery life but also damage the lithium battery. It seems that the use of lithium batteries must be handled with care. As for the factor of increasing battery life by shallow charging and discharging, it mainly extends the number of days of use, and the battery’s actual usage time does not increase much. However, there is no need to worry about this because lithium batteries have protection boards that have designed charging and discharging voltages to be shallow. Although it may seem like there is still a lot of electricity left after discharging or still room for charging after being fully charged, the voltage limits are set to ensure the battery’s cycle life, capacity, and safety performance. Therefore, it is unnecessary to worry about shallow charging and discharging. Some people may ask if shallow charging and discharging can still increase the battery’s life. Yes, it can, but it would lose the battery’s energy storage purpose. Remember that safety is the most important factor in using lithium batteries.