How long is the battery life? カスタマーセンター October 25, 2017 08:23 Updated Follow The batteries will last for about an year with 10 operations per day. Related articles How can I check the remaining battery life? I can't figure out how to insert the batteries. What kind of batteries should I use? Can I attach the NinjaLock onto doors where the thumb turn is combined with the door knob? Can I attach the NinjaLock onto sliding doors? Comments 0 comments Please sign in to leave a comment.