How often should you replace detector batteries?

Why it matters

A chirping detector gets its battery pulled at 2 a.m. and never replaced. Doing the whole house on one date each year removes the guesswork.

How to do it

Replace the batteries in every smoke and CO detector on the same day, even the ones that haven't chirped. Many people tie it to the fall clock change.

Signs you've waited too long

Chirping at night — or a silent detector that no longer chirps at all.

Same part of the house