First Alert Smoke Alarm 9120B Battery Replacement

Written By: Miggy Reyes
  • Comments: 10
First Alert Smoke Alarm 9120B Battery Replacement

Difficulty

Easy

Steps

7

Time Required

1 - 3 minutes

Introduction

Follow this guide to fix your First Alert Smoke alarm. This fix will stop the First Alert Smoke alarm from beeping when your battery is low.

Make sure you have your 9V battery in hand and a helper to make sure that you do not fall from your stool. These alarms are usually found mounted into your ceiling so please take precautions when unmounting the alarm.

As you will be working with wires, please make sure that you are gentle with the alarm since it is easy to break the covered wires if you are too aggressive with it. All of these steps should require very little strength. If you find yourself needing to force things into place, please review the steps to make sure you are properly uninstalling/installing the smoke alarm.

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    • Remove the alarm by rotating it counter clockwise in the mount.

    • The alarm should fall off once rotated enough. The cable should be the only thing holding it in place if done correctly.

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    • Unplug the cable from the alarm.

    I can’t unplug the cable from the alarm

    Jerusalem -

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    • Press down on the catch on the top left of the alarm to open the battery compartment.

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    • Remove the battery and dispose of it properly.

    • Replace the old battery with a new 9V battery and close the compartment.

    • You should hear a click to know that the compartment is secured.

    This is horribly designed as it's very hard to remove the battery and I can't insert a new one

    Frank -

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    • Line up the holes of the cable on the mount with the pins on the alarm.

    • Reconnect the cable on the mount to that on the alarm.

    • It should insert itself with minimal force.

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    • Press the alarm into the mount.

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    • Rotate the alarm clockwise until it does not turn anymore. This makes sure the alarm is secured.

    How do I reattach the battery door if it came off?

    Sheryl Hage -

    Just open the battery compartment,slip out the battery

    Now slip a new 9 v in place

    Don’t have to remove entire thing!

    Henk van Wyk -

    is there anyway to safely take it apart and see what inside

    MckayleGaymesYT -

Author

Miggy Reyes

Member since: 15/02/21

219 Reputation

5 comments

How do I disconnect the cable? Seems very tight and cannot disconnect.

Jeanne O -

This is related to first alert smoke alarm 9120B. Can not remove connecting cable from alarm. Is very tight. So unable to change battery. Any suggestions?

Jeanne O -

These alarms suck! Pressing the tab and the battery compartment does NOT pop open. I needed a knife to pry it open, and then it had to be forced close. NOT user error! The plastic pins that hold the battery compartment closed don't move out of the way enough to allow opening.

James Durso -

I replaced the battery and it is still beeping, reset the smoke alarm. What should I do now?

Donald Sandford -

Buy and install a new alarm. It’s easier than trying to fix on.

Stephen Taylor -