Overcharging the battery will not only cause the battery performance to decline, but also sometimes cause overheating or even smoke and fire. When the battery is discharged below the lower limit voltage, it is still required to continue to discharge, which is called over-discharge.
When the battery is over-discharged, a chemical reaction that is different from the normal state will occur inside the battery, resulting in irreversible changes in the internal active substances, reducing the battery capacity, and in severe cases, the single battery will be unusable.