What is the battery icon in the SmartLine display used for?

The battery icon in the display indicates to different setting based on the dial position. When the dial is in the SMART (Auto-Adjust) position, the battery icon reflects the battery strength of the SLW weather station. When the dial is in all other positions, the battery icon reflects the strength of the 9V battery installed in the access compartment in the back of the panel. SmartLine Controllers use a Real Time Clock/Calendar instead of a backup battery to maintain correct time during a power outage. For the SL1600, SL4800, and SL9600TW the display will show a blank battery icon in the display until/unless a battery is installed in the controller. Battery usage is only necessary for programming when the control panel is removed.