When mine go off they all go off so there's no telling which one has the dead 9v battery. So the only 2:00 AM solution is to remove the battery on all of them, turn off the breaker for the smoke alarms, then wait five-ten minutes for their capacitors to drain and stop the chirping. Don't ask how I know this.
BTW, the reason that the wee hours is their favorite time to go off is that most people turn the heat down overnight. When the battery is just about dead but not quite there yet, that reduction in temperature is just enough to reduce the voltage enough to set off the chirping.
BTW, the reason that the wee hours is their favorite time to go off is that most people turn the heat down overnight. When the battery is just about dead but not quite there yet, that reduction in temperature is just enough to reduce the voltage enough to set off the chirping.