An ADT glass break sensor listens for the sound of breaking glass and tells the control panel, and it runs on a battery that has to be replaced when the panel reports it low. Home Tech Nerves and installer guides say the sensor uses a CR123A lithium battery, a small, long-lasting cell, though you should check the type printed inside the sensor or in its manual, because models differ.
The checks in more detail
The usual sign of a weak battery is a low-battery message on the panel, and sometimes a chirp from the sensor or the panel that repeats at intervals; a JustAnswer thread describes an alarm making a funny noise and saying that the glass sensor battery was low. The chirp often starts at night when the temperature drops, because cold lowers the battery's voltage, and it may stop in the morning and return, which is a sign that the battery is close to the end.
To replace it, open the sensor's cover, which is a snap-on or sliding panel that you may need to release gently with a flat tool, remove the old battery, noting its direction, and fit a new one the right way round. Use a fresh, good-quality lithium cell. Before you open the sensor, put the system in test or maintenance mode if your panel offers it, so that opening the sensor does not trigger a tamper alarm, and tell the monitoring company if they monitor the system.
After the swap, close the cover, and the sensor reports to the panel again; the low-battery message should clear, or you clear it by following the panel's instructions, often by pressing OFF or the keypad's clear sequence. Test the sensor using the manufacturer's test method, which may use a special glass-break tester, and do not break glass. If the message returns quickly, the new battery is faulty, the sensor's contacts are dirty or the sensor is failing. Dispose of the old cell at a battery recycling point. Keep spare cells out of reach of children, and write the date of the change on a sticker inside.
Differential
Likely causes of “ADT Glass Break Sensor has power or battery problems”, and how to tell them apart
- 1
A weak CR123A
What separates it A low-battery message and a chirp
How to confirm Replace it with a fresh lithium cell
- 2
Cold weather
What separates it The chirp starts at night
How to confirm Replace the battery; cold exposes a weak cell
- 3
The battery fitted the wrong way
What separates it The sensor does not report
How to confirm Check the polarity
- 4
A tamper alarm when opening
What separates it The panel alarms
How to confirm Use test mode and inform the monitoring company
- 5
A failing sensor
What separates it The low-battery message returns quickly
How to confirm Ask the installer to replace the sensor
Before you touch a setting
Record this first — changing settings destroys the evidence
- The battery type printed in the sensor
- When the chirp occurs
- The panel's message
- The date of the last battery change
Try in this order
0 of 6 completedPut the system in test mode
ReversibleIf the panel offers it.
Open the sensor's cover
ReversibleRelease the snap or slide gently.
Replace the battery
ReversibleWith a fresh lithium cell, right way round.
Close the cover
ReversibleAnd wait for the sensor to report.
Clear the low-battery message
ReversibleAs the panel instructs.
Write the date inside
ReversibleFor next time.
Model-specific
What is true of this model and not of its siblings
- Cold chirps
- A low battery shows first on cold nights.
- Test mode
- It prevents false alarms.
Stop boundary
When this stops being a self-service repair
- !If the message returns after a new battery, ask the installer to check the sensor
- !If the system alarms when you open it, tell the monitoring company
- !Do not break glass to test
Evidence ledger
Sources behind this answer
The CR123A lithium battery in glass break sensors.
A low-battery chirp from a glass break sensor.
Camera, doorbell, sensor, battery and reset troubleshooting for ADT systems.
Exact questions
Common questions
What battery does an ADT glass break sensor use?+
Commonly a CR123A lithium; check the label.
Why does it chirp at night?+
Cold lowers a weak battery's voltage.
Do I need to tell the monitoring company?+
Yes, if they monitor the system.
How do I test it?+
With the manufacturer's tester, not by breaking glass.