Batteries in wireless Insteon devices like the Hidden Door Sensor or Motion Detector can last anywhere from 3 months to a year, depending on usage and configuration, but it’s tough to estimate just how long that time window is without testing under actual conditions. For example, the battery in the door sensor is likely to last much longer on a door that’s infrequently used compared to one that’s used daily. Or a motion sensor configured to only send “on” commands after-dark will last much longer than one configured to send both “on” and “off” all day long.
To get a better idea how often you should be replacing batteries in these devices, I recently started implementing a new trick when replacing batteries: label them with the date they’re installed. That way, when the battery finally dies, you can immediately see how long the old one lasted before needing to be replaced. Of course, you could just log all this information somewhere to capture things like how the motion sensor settings affect battery life, but using a $10 label maker will help for those times when you forgot to log when you did the replacement.