Did old battery powered smoke alarm with a buzzer have any low battery notification? My old house had 2 and I don’t recall them ever warning us of a low battery. We only replaced the batteries once after around 5 years in the house, after thenold batteries were long dead.
Nope.
Somewhere a long the line they made a button you could push to see if the smoke detector still even worked (it’d beep or buzz or whatever it did). Before that they didn’t even have lights or anything, it was just routine to replace the batteries every year.