– Alkaline batteries: Criterion for replacing the batteries: Battery voltage lower than about 1.9 V➝ Replace the batteries.
– Lithium batteries: Criterion for replacing the batteries: Ah drawn Lithium battery, DD type: > approx. 20 AhLithium battery, D type : > approx. 10 Ah➝ Replace the batteries.
(For technical reasons, the battery voltage displayed cannot not be used as a criterion for replacing lithium batteries.)