Most battery-operated motion sensors will go to sleep for a period of time in order to conserve battery. For example, the guide for my Ecolink Z-Wave Plus Motion Sensors state, "Will wait 4 minutes after a motion is detected before checking occupancy again, to save battery".
This is where I always get confused.
If the motion sensor goes to sleep for 4 minutes following a sensed motion, does it wake up after 4 minutes, look to see if motion is occurring then go back to sleep, or does it remain in a sensing mode until it senses motion?
Let's say you want a motion sensor to keep the lights on when a room is occupied and turn the lights off when the room is empty. You create a rule to turn the lights on immediately upon sensing motion and turn the lights off after 30 minutes of inactivity. What happens if the room is occupied but each time the motion sensor woke up to check, there wasn't any moving for it to detect?