How to Replace Sensor Batteries on an ADT Home Alarm System

The batteries must be replaced periodically in the sensors of your ADT home alarm system. These sensors are located in doors and windows. Once you see the LO BAT or BAT message on the sensor, it is time to replace the batteries, which can be done without the help of a professional.

The batteries on your alarm system need to be replaced.

Step 1

Look at the keypad display to determine which sensors need to be replaced. The screen will display a description, point number or zone number that tells you the location of the sensor.

Step 2

Write down the model number of each sensor that needs its batteries replaced.

Step 3

Purchase the replacement Panasonic or Duracell CR123A batteries from a local retail store. If you are unable to locate these batteries, contact ADT to have the appropriate batteries sent to you.

Step 4

Turn the alarm system to test mode by navigating to and entering your Personal Identification Code (PIC). If you are unable to successfully turn your system to test mode, call ADT and request for them to place the system in test mode for you.

Step 5

Remove the cover from the sensor using a flat blade, such as that of a screwdriver, to insert into the seal and pry off. Newer models of the ADT sensors feature a finger latch for easier removal.

Step 6

Inspect the existing battery for leaks or damage. If there are leaks, contact an ADT specialist to proceed with replacement. If you do not notice any type of damage, proceed with removing the old battery from the sensor with a small screwdriver.

Step 7

Insert the replacement battery after waiting for at least 30 seconds. When inserting the new battery, check to make sure that you have the appropriate side inserted that matches up with the polarity (the + and – signs).

Step 8

Replace the cover of the sensor, ensuring that it is secured into place and activate it by opening and closing the window or door that it monitors. Once you have successfully activated the sensor, you will hear three beeps from the keypad as a confirmation.

Step 9

Check the keypad screen to ensure that the LO BAT or BAT message is no longer displayed. If it is, contact ADT to schedule a service call.

Test the System

Step 10

Test the sounder and display test by pressing the star key, 6 [your master code] and 4. Once you have completed this sequence, you will see all indicator lights and pixels displayed as well as a medium-level bell followed by a full-volume bell for two seconds each.

Step 11

Press the pound key to stop the sound and display test.

Step 12

Check to ensure that the "Ready" light is on and the system is disarmed before proceeding with the "Walk" test.

Step 13

Initiate the "Walk" test by pressing the star key, 6, [your master code] and 8.

Step 14

Activate the sensor that needed the battery replacement by opening the door or window it monitors.

Step 15

Check the display to ensure that it shows "Secure or Arm System," "Secure System or Enter Code" or "Secure System Before Arming". This shows that the system recognizes the door or window is open and that the sensor is in proper working condition.

Finishing Steps

Step 16

Remove your alarm system from test mode by navigating to or by calling ADT directly.

Step 17

Recycle the old batteries once the entire process is complete (see Resources).

Step 18

Arm your security system to continue protecting your home.