When batteries and rechargeable batteries are discharged, they reach a voltage value at which electrochemical conversion no longer takes place. The battery or accumulator is then "empty". The terminal voltage then corresponds to the end-of-discharge voltage.
While batteries must be replaced when the end-of-discharge voltage is reached, rechargeable batteries can be recharged.
To avoid damage and reduction of battery life, the end-of-discharge voltages should not be undercut by deep discharge. Final discharge voltages depend on the battery type and are between 0.8 V and 0.9 V for NiCd batteries, 1.0 V for NiMH batteries, 2.5 V for lithium-ion batteries and 1.75 V for lead batteries.