There has been a beeping coming from the apartment next door for at least 45 hours now. It started as one beep every 3 seconds and after about 6 hours it changed to 3 beeps then a 2 second pause then repeat. I thought it was their smoke detector battery dying but I’ve never hear one beep this long or long enough to change the pattern so now I’m not sure. If it is a smoke detector, how long until the battery finally dies?

dealing with death