My 2-years old CO detector (small, wall-mounted device with battery, no other power source) started beeping every morning for at least few minutes, sending sharp chirps once every 10 sec. It starts around 6am.
I don't see any visible fire or cooking in my apartment or outside. I've read that it might mean end of battery/detector life, temperature change, or poltergeist. Are these the most common reasons?
I will replace battery to check for some of it.
UPDATE: Changed battery, chirping went away