[masraum]

Originally Posted by MikeSid

You change them.

With the one I have, it will flash a light at you for quite some time alerting you to change the battery. You'd have to ignore it for a long time before losing power.

Some also use a key as a backup as well. The battery is changed from the secure side of the door, so as long as you have key access to that area via a back up system, or some other access to the secure side of the door, you won't have an issue.

Our kids' have the backup key, but I don't know if they always carry it. I'm sure theirs either beeps or flashes a light or something. They probably either forget what that means or are so busy and distracted that they don't heed it until it's too late.