The ADT keychain remote runs on a small coin cell, and when it fails the signs are a fob that works only when you stand close to the panel, a light that no longer flashes when you press a button, or a low-battery message on the panel that names the fob. A weak coin cell loses range first, so a fob that used to work from the driveway and now works only at the door is a battery warning, not a fault.
The checks in more detail
To change it, find the type printed in the battery compartment or in the manual, since fobs differ, open the case by prising the two halves apart with a thumbnail or a small flat tool, noting how the battery sits, and fit a fresh cell the right way up with the positive side as shown. Close the case until it clicks. Do not use a flat tool that could crack the case, and keep spare coin cells away from children, as swallowed batteries are dangerous.
After the change, press a button and watch the fob's light, then test it with the panel: arm and disarm, and check the panel responds from the distance you use. If the fob still fails, check that it is still enrolled, since the panel may have cleared the fob during a reset, and enrol it again. A fob that drops out in cold weather has a battery on its last legs, so fit a new one before winter.
Coin cells vary in quality, so choose a known brand and check the date. Keep the fob away from water and from heavy knocks. If the fob does not respond with a new battery and is still enrolled, the unit is worn or faulty, and a replacement is cheap compared with the risk of being unable to arm. Write the date of the change on a note near the panel, and replace the batteries yearly if you use the fob daily.
Differential
Likely causes of “ADT Keychain Remote has power or battery problems”, and how to tell them apart
- 1
A weak coin cell
What separates it The fob works only near the panel
How to confirm Fit a fresh cell
- 2
The battery the wrong way up
What separates it The light does not flash
How to confirm Check polarity
- 3
Cold weather
What separates it The fob fails outdoors
How to confirm Replace the battery before winter
- 4
The fob cleared from the panel
What separates it It does nothing with a new battery
How to confirm Enrol it again
- 5
A worn fob
What separates it It fails with a good battery
How to confirm Replace the fob
Before you touch a setting
Record this first — changing settings destroys the evidence
- The battery type in the compartment
- How far the fob works from
- Whether the light flashes
- The panel's low-battery message
Try in this order
0 of 6 completedFind the battery type
ReversibleIn the compartment.
Open the case
ReversibleGently.
Fit a fresh cell
ReversiblePositive side as shown.
Press a button
ReversibleAnd check the light.
Test arm and disarm
ReversibleFrom your usual distance.
Enrol it again
ReversibleIf the panel forgot it.
Model-specific
What is true of this model and not of its siblings
- Range
- It is the first thing to drop.
- Safety
- Coin cells are dangerous if swallowed.
Stop boundary
When this stops being a self-service repair
- !If a new battery and enrolment fail, replace the fob
- !If the panel keeps reporting low battery, ask the installer
- !Keep spare cells safe
Evidence ledger
Sources behind this answer
Exact questions
Common questions
What battery does the ADT fob use?+
A coin cell; check the compartment.
Why is the range short?+
A weak battery.
Does cold matter?+
Yes, weak cells fail first in the cold.
How often should I change it?+
About yearly with daily use.