Why is the motion detector beeping?

he keypad reads, "No AC."  What does that mean?

Why is the smoke detector beeping?

A contact fell off the windowsill.  What do I do?

Q Why is the smoke detector beeping?

A Battery operated and electrical smoke detectors beep when their batteries begin to lose their charge but the USA Abel smoke detector does not because it is not equipped with a battery.  The USA Abel smoke/heat detector used the rechargeable battery located in the panel box, as does the rest of the alarm system.