If (and I hope you do) have smoke/fire detectors and change the batteries every year (at the time change) (I do it in the fall) the batteries probably are still good. I use them in battery back-up clocks or any control device I have.

Use them that way and when the battery goes bad it is easy to change and does not cause a potential life threatening situation and you get the full life out of the battery.

Blessings