Why do Li-Ion cells have a Cut-Off voltage?

The cut-off voltage in a cell refers to the minimum voltage at which the cell should be considered fully discharged. Below this voltage, the cell's capacity is considered to be exhausted, and continuing to discharge it further could damage the cell or reduce its overall lifespan.

The cut-off voltage varies depending on the type of cell or battery being used, as well as its specific chemistry and construction. For example, a lithium-ion battery might have a cut-off voltage of around 3.0-3.3 volts per cell, while a lead-acid battery might have a cut-off voltage of around 1.75 volts per cell.

It is important to monitor the cut-off voltage of a cell or battery to ensure that it is not discharged beyond its safe limits. Discharging a cell too deeply can cause irreversible damage and reduce its overall lifespan, while over-discharging a battery can be a safety hazard and may even cause it to explode or catch fire.