My brk model no 86rac alarms went off - not the "chirp" of a bad battery - but rather they went OFF. We have three - and they would go off for about 2 minutes and then stop, every 2 - 3 hours last night. I finally pulled the bedroom detector out, which stopped the other two, but it continued to sound in my hand until I pulled the battery. Do we just need to replace all three with new model? I don't believe there is a fire lurking anywhere, since it's been more than 12 hours.