In Australia, smoke alarms typically use either 9 volt alkaline batteries or 10 year lithium batteries. Mains powered alarms may have a 9 volt backup battery. Replaceable 9 volt batteries need to be replaced annually, whereas 10 year lithium batteries can last the life of the alarm without needing to be replaced.
9 volt alkaline batteries:
These are the common type of battery found in many smoke alarms, particularly those that are battery powered or have a backup power source for hardwired alarms.
10 year lithium batteries:
These batteries are designed to last the life of the smoke alarm (usually 10 years) and are typically used in hardwired alarms or those that are sealed units.
Replacement frequency:
9 volt batteries should be replaced annually, or when the alarm indicates that the battery is low (e.g., it beeps).
10 year lithium batteries do not need to be replaced during the life of the alarm.
Testing:
Regardless of battery type, it is recommended to test the smoke alarm monthly by pressing the test button to ensure it is functioning properly.