The cut-off voltage of the discharge is higher or lower depending upon the discharge current. The relationship between the discharge current and the recommended cut-off voltage is shown in “Discharge characteristics”. Do not discharge the batteries lower than this recommended cut-off voltage. When the batteries are discharged lower than this cut-off voltage, they may be over discharged
It is important to avoid over discharge. Charge the battery immediately after discharge.
Even if the discharge of the batteries are stopped before the batteries reach the recommended cutoff voltage, the batteries may deteriorate if they are not charged after discharge and stored instead.
If a circuit (or device) for preventing over discharge (and weak current as well) is not provided for the equipment, the batteries may be over discharged and may not recover their capacity after charging.
When the batteries are stored in the discharged state, they may have difficultly recharging due to the increase in the internal resistance.