Warning: check your smoke alarm battery date before the time change, my Saturday with a chirping hallway
Last Saturday at 2 in the morning I woke up to that short chirp every 40 seconds coming from the hallway outside my bedroom. I dragged a chair out, pulled the unit down, and found a battery from 2019 still in there, so I swapped in a fresh one and it went quiet. Two days later my neighbor on the same block said her alarm never went off during a small kitchen fire, and I went back and checked mine with the test button and it was dead quiet. Turns out the old battery had gone soft enough that the unit had no real backup, and the new one tested fine, so now I pull each alarm down every month and hit the button. If your alarm is more than 8 years old, how are you keeping track of when to replace it?