The ADT Keypad runs on AC power with a lithium-ion backup battery, and ADT's No AC Power article describes its states: when AC power is lost the keypad waits two minutes before entering backup battery mode, and the Disarm button turns solid yellow with the power LED blinking red every two seconds when the backup battery is low, showing only if the keypad is awake from motion.
The checks in more detail
Devices run on backup for up to 24 hours, and after power returns a Low Backup Battery message may last up to six hours while it recharges. ADT has an article on replacing the Keypad's backup battery, and warns not to recharge, disassemble, heat above 212 degrees Fahrenheit or incinerate the lithium battery. Check the power supply is plugged in and the outlet works. The Keychain Remote uses one CR2450 battery, per ADT's low battery article.
The Yale Assure Lock 2 is battery powered and keeps working during a power outage, and ADT's Yale article has a battery section; use fresh cells and keep a physical key. If a low battery message persists 24 hours after replacement, delete and re-add the device. Extreme temperatures degrade battery life. Write the date on any battery you fit so you know its age at the next warning. Cold weather cuts battery life, so a lock that warns in winter may be fine in spring.
Keep spare CR2450 cells for fobs in a labeled box. ADT's Keypad backup battery is lithium-ion and comes with caution notes, so replace it only with the correct part and dispose of the old one at a collection point. A lock that works through an outage is a benefit, but only if its batteries are fresh, so put lock battery changes on the same date as smoke alarm changes each year.
Differential
Likely causes of “ADT Keypad, Keychain Remote and Yale Assure Lock 2 has power or battery problems”, and how to tell them apart
- 1
An outage
What separates it The Keypad has switched to its backup battery because mains power was lost and it waited two minutes
How to confirm Wait for the mains power to return, and check the Keypad goes back to normal operation
- 2
A low backup battery
What separates it A yellow Disarm button shows because the Keypad's backup battery is low and needs to be replaced
How to confirm Replace the backup battery as ADT's article describes and check the yellow button clears
- 3
A dead fob battery
What separates it The keychain fob does nothing when you press it because its CR2450 battery is dead
How to confirm Replace the CR2450 battery in the fob and press a button to check the light responds
- 4
Low lock batteries
What separates it The lock is slow to respond or shows offline because its batteries are getting low
How to confirm Replace the lock's batteries with fresh ones and check the lock reconnects to the Base
- 5
A message that will not clear
What separates it The low battery message stays after a replacement and the device is still reported as low
How to confirm Delete the device in the app and add it again so that its old battery state is cleared
Before you touch a setting
Record this first — changing settings destroys the evidence
- The Keypad LED pattern and whether the Disarm button is yellow
- The battery state of the Keypad, fob and lock
- How long it is since mains power returned after any outage
- Which device shows the low battery message
Try in this order
0 of 7 completedCheck the Keypad supply
ReversibleCheck the Keypad supply is plugged in and the outlet works, since the Keypad runs on AC power with a backup battery for outages.
Test the outlet
ReversibleTest the outlet with another device such as a lamp, so you know whether the outlet is the reason the Keypad lost power.
Read the LED
ReversibleRead the LED: a yellow Disarm button means a trouble state, and a red blink can show the Keypad is running on its backup battery.
Replace the backup battery
ReversibleReplace the backup battery following ADT's article, using the right lithium-ion battery, and refit the cover carefully.
Replace fob and lock batteries
ReversibleReplace the fob and lock batteries with the right type, which is a CR2450 for the fob and the cells listed for your lock.
Wait 6 hours after outage
ReversibleWait six hours after an outage for the backup battery to recharge, and do not judge the Keypad's battery until then.
Contact ADT
ReversibleContact ADT if the Keypad stays dead or the battery message will not clear, and tell them which device is affected.
Model-specific
What is true of this model and not of its siblings
- Keypad
- AC plus a lithium-ion backup.
- Lock
- Battery powered, works in outages.
- Other models this page answers
- These steps also fit the Yale Assure Lock 2 / Lock 2 Touch.
Stop boundary
When this stops being a self-service repair
- !If the Keypad has no power after checks, contact ADT through chat
- !If the backup battery fails, replace it, because the Keypad will not work in a power cut without it
- !If a lock battery dies, use the key
Evidence ledger
Sources behind this answer
AC power and backup battery.
Battery types and lives.
Keypad backup battery.
Yale lock setup, use and battery.
The company and its products.
Exact questions
Common questions
How long is Keypad backup?+
The Keypad's backup battery keeps it working for up to 24 hours after mains power is lost, which covers most power cuts.
How long before backup starts?+
The Keypad waits two minutes after AC power is lost before it switches to the backup battery and reports the loss.
Does the lock work in an outage?+
Yes, the lock keeps working in a power outage because it runs on its own batteries and not on the mains supply.
What does a yellow Disarm mean?+
A yellow Disarm button means a trouble state, such as a faulted device or a low battery, so check the trouble list in the app.
Can I recharge the backup battery?+
Follow ADT's article for the backup battery, which explains when it needs replacing and how to fit the new one.
Do I keep a key?+
Yes, keep a key for the lock in case its electronics or batteries fail and you need to open the door.
What is the Release Key for?+
The Release Key is used for removing the Keypad from its mount, so keep it somewhere safe once the Keypad is fitted.
Can the Keypad be wall mounted?+
Yes, the Keypad can be wall mounted with the bracket, screws and anchors that are supplied as options in the box.
Why would the Keypad be offline?+
A Keypad goes offline when its power supply fails or its backup battery is depleted, so check power before anything else.