Today, I changed the batteries in all my smoke detectors. I noticed that the battery light in one was blinking. Instead of only replacing the one with a new normal 9v battery, I ordered a pack of 10-year lithium 9v batteries and replaced them all. Now I don’t have to worry about changing them for a handful of years.

Edit - Funnily enough, dinner put them to the test. I was going to test them tomorrow when the kiddo is at daycare.