I know it is not boat related, but I am losing my mind. I have 6 (yes 6) smoke alarms in the house here upstairs. So I woke up the other night to one of them chirping at me. Went out and unplugged it to shut it up. Then went out and bought all new 9v batteries for them, and have gone around and replaced them all with new 9v's. Tested them and they all went off at the same time as they are supposed to. Thought all was done, and lo and behold, it's still chirping back there. Driving me nuts. Any ideas from you guys. I am out of answers...next step is just to go back and unplug it from the ceiling and leave it.