How long does the back up battery last on a garage door opener? Support May 25, 2023 16:19 Updated The back up battery lasts an estimated time of 1-2 days on normal usage in an electrical power outage. Related articles Why is my wall button working but my remote is not on my garage door opener? Where can I order service parts? How do I handle or claim a warranty on my tool? How do I register my tools? Where can I locate information about my pressure washer? Comments 0 comments Please sign in to leave a comment.