what kind of batteries do smoke detectors take

Smoke detectors typically use the following types of batteries:

1. 9V batteries: These are the traditional and most common batteries used in smoke detectors. They usually last about 6 months to a year and are easy to replace.
2. AA batteries: Many modern smoke detectors use two or three AA batteries, which last longer than 9V batteries, around 12 to 18 months.
3. Lithium batteries: Some smoke detectors come with sealed lithium batteries designed to last 5 to 10 years, often for the lifetime of the detector without needing replacement.
4. CR123A or 123 batteries: Used in high-performance or smart smoke detectors, these lithium batteries typically last 3 to 5 years.

The exact battery type depends on the smoke detector model, and some newer devices have built-in lithium batteries that don’t require replacement for up to 10 years.