I usually use the battey back up type, and one bad battery will set a warning alert, and occasionally set them all off. Sometimes customers will reffer to the "battery warning beep" as it going off too.
Also, if one has no power, and the rest do, this will set it off randomly too. Check the status light on all of them. BRK is green for OK, red for no power. I had a hair puller like this once due to a bad harness.
