My smoke detector is chirping. What does that mean?

Most modern smoke detectors will chirp to alert you when the batteries are low. You should replace the batteries and test your smoke detector. The National Fire Protection Association (NFPA) recommends replacing all smoke alarms when they are 10 years old and / or replacing a smoke alarm if it does not respond properly when tested. The NFPA suggests testing smoke alarms monthly using the test button. Smoke detectors can be purchased at any hardware or large commercial department store.