The protection circuit module is an important part of the lithium battery pack.  Its main functions are over-charge, over-discharge, over-current and short circuit protection.

Over-charge protection: charging the product, when the voltage reaches the maximum voltage of the battery, the circuit module will automatically turn off and it shows that the battery is fully charged and will not continue charging, which form an over-charge protection.

Over-discharge protection: when the battery is running out, the voltage reaches a required minimum value, the protection circuit module will be turned off, and the discharge will not occur. The product will automatically shut down, which form an over-discharge protection.

Over-current protection: when the battery is discharged, the protection circuit module will have a maximum current limit. Different products are different, when the discharge current exceeds this limit value, the protection circuit module will also automatically close.

Short-circuit protection: when the battery is inadvertently short-circuited, the protection circuit module will automatically turn off within a few milliseconds, and will not be energized.  At this time, even if the positive and negative poles touch one piece, nothing will happen, it will be fine, which form a short-circuit protection, and will not cause an explosion to occur.

The protection circuit module is a charge and discharge protection for the series lithium battery pack, when the battery is fully charged, the voltage difference between the individual battery cells can be ensured to be less than the set value, thereby realizing the equalization of the battery cells of the battery pack, and effectively improving the charging effect in the series charging mode.  At the same time, the over voltage, under voltage, over current, short circuit and over temperature of each single cell in the battery pack are detected, protect and extend battery life, under voltage protection prevents each single cell from over discharging during discharge.