Customer FAQs Discover answers to the most frequently asked questions from ADT customers with the click of a button. 1. If I lose power, will my alarm system still work? Yes. In case of a power loss, the back-up battery will activate and will operate your alarm system for several hours. In the event your system battery is or becomes low, a low-battery signal will be sent to ADT’s Customer Monitoring Center. Your system will also show an indication of the low battery by displaying a message (e.g., LOW BATT or BATT) on the keypad or frequently beeping. Learn what steps to take for a low-battery signal.