If there is a mains power failure, how long will your smoke alarms function?
User-replaceable Battery Type (9V Alkaline Battery)
Australian Standard (AS) 3786:2014 specifies that the standby mode in a smoke alarm should be capable to run for at least one year before the battery-low fault is shown. It should be followed by 30 days of a battery fault warning. The alarm should be capable of buzzing for at least 4 minutes.
Rechargeable battery type (non-removable 10-year lithium battery)
Australian Standard (AS) 3786:2014 specifies that the standby mode in a smoke alarm should be capable to run for at least 72 hours before the battery-low fault is shown. It should be followed by 24 hours of a battery fault warning. The alarm should be capable of buzzing for at least 4 minutes.
It is the minimum standard. Most of the manufacturers claim that their batteries provide more power back-up than what is required.
All the consumer’s need to be aware of manufacturer’s instructions regarding the battery replacement in mains-powered and rechargeable smoke alarm batteries. A short beep might sound every 40 seconds to 2 hours. It might be longer if the battery is totally drained during the period of mains failure.