Low Power Mode is enabled by the fire alarm control panel when operating on batteries during mains power loss. When activated the loop polling rate is reduced and the device CPU's are 'put to sleep' during polls. 

This significantly reduces the device standby current and hence the overall loop loading, Loop current is reduced by 60 to 70% thereby allowing smaller batteries to be installed. 

Fast call point and sensor fire response is maintained by the built in interrupt system and overall system performance still meets the current standards' requirements.