Prevent damage to those back up flashlights, testers or other devices that receive occasional or little use by removing the batteries. Sometimes you can save a device after a battery has leaked acid into it, usually it ends up in the circular file.
Good Suggestion. I have a vacuum sealer at home for food storage. I took my old IR thermometer and sealed it with a new 9v battery and put it in the car incase needed. keeps it clean & ready for use if needed.