ADT wireless alarm systems use 9-volt or 3-volt batteries in the door and window sensors. The door and window sensors operate the chime within your ADT system. When the alarm chirps and the display indicates a low-chime battery, replacement of the sensor battery is necessary. Batteries for the alarm sensors are available at home improvement centres. Although there are many models of wireless alarms, the sensor/chime battery replacement is essentially the same.
Call the monitoring service and inform them that you are replacing batteries. Disarm the security system now if it is not already disarmed.
Go to the sensor in need of battery replacement, and look for a small screw or thumb tab along the bottom or top edge of the sensor. Remove the screw with a small Phillips-head screwdriver. Pull the sensor cover off of the sensor base. For sensors with the thumb tab, lift the thumb tab out with your finger to pull the sensor cover off.
Pull out the old battery and insert a new 9-volt or 3-volt alkaline battery, depending upon your sensor. Place the cover over the sensor base, and push in until the thumb tab locks the cover. Secure the cover with the retaining screw, if your sensor uses a screw.
Insert your four-digit user code into the keypad of your system and press the "Test" button. The ADT alarm system will check all of the sensors and inform you through an audible beep and voice of their condition. Once all of the sensors are verified by the system, enter your code again and press the "Off" button. Call your monitoring service when you complete the battery change.
Test your ADT alarm system once a week using the method detailed in step 4.