Since the interface's internal clock may drift while depending on the battery, Thinking Home will automatically set the interface clock to the Macintosh clock when this happens.

For the ActiveHome (CM-11), IBM Home Director (CM-10) and the CP-10, the battery is used to maintain the clock. The Events and Macros are stored in such a way that they are maintained, even if the battery is low or missing.

For the CP-290, the battery backs up both the clock and the events. When the battery is low or missing, the condition is reported and the interface will need to be provided the clock and event schedule again.