In some Kidde alarms with a "pop-out" battery door, you'll need to take care that the Roost battery is positioned against the battery door clip. If the Roost battery is not positioned against this clip, then the battery may not make good contact with the alarm's power terminals, causing a low-battery chirp from the alarm.
Please see the image below to see a Roost Smart Battery installed incorrectly in a Kidde alarm with "pop-out" battery door:
Please see the image below to see a Roost Smart Battery installed correctly in a Kidde alarm with "pop-out" battery door. The Roost battery needs to make contact with the clip on the battery door in order for it to power the alarm correctly:
Although the Roost battery is made to ANSI standards for 9V batteries, it appears to be too big for the Kidde KN-COPE-IC specifically. The alarm battery door clip gets stuck on the Roost battery Smart Module and can dislodge the Smart Module. Use a small screwdriver to gently lift up clip preventing it from catching on the battery as you install it. Please see below images for further clarification.