In the ADT alarm system, the back of the main alarm keypad -- the battery drawer -- contains either one 9-volt alkaline battery or six 1.5-volt alkaline batteries, depending on your system. In addition, all additional remote sensors also contain batteries. Remote sensors either contain one 9-volt alkaline battery or one 3-volt lithium battery.
The battery life of ADT alarm system batteries is up to 4 to 5 years for most home alarm system batteries. Battery life for batteries used in ADT's commercial alarm systems vary. A display message of 00 on the master keypad represents a low battery and indicates the need to change the battery within 30 days.
As a security precaution, only replace batteries with the same type of battery removed. For example, if your alarm system consists of a lithium battery, replace it only with a lithium battery.