How To Replace The Battery In Your Wireless Window/Door Sensor

By installing a wireless home security system in your home in Charleston, the time may come eventually that you’ll have to replace a battery in one of your wireless window/door sensors. The good news: it’s easy to replace and by doing it yourself, you can save a bit of money.

The batteries used in your door sensors can last for years after installation depending on use, but like all batteries there is a set lifetime and will have to be replaced.

Most companies will charge you a service fee if they have to send a field security system technician to your home, so by following these quick, simple steps you can avoid that charge all together.

Note: This guide is for use for Honeywell 5816 Door/Window Transmitters. Not sure what model your sensor is? Give us a call: (843) 789-9994.

1. Determine Which Sensor Has A Low Battery

When a wireless sensor in your home security system has a low battery, your keypad will display a “lo bat” message, followed by a number that will tell you which zone has a low battery. The “zone number” corresponds to the area of you home that sensor is protecting. If you’re not sure about zone list, you can always give us a call or check the security app, if you are using one.

2. Put Your Alarm System in TEST Mode

At your keypad, enter your user code (the four digit code you use to arm/disarm your alarm) + the number 5. You’ll note on most keypads you’ll see the word “TEST” on the number 5.

Putting your alarm in TEST mode prevents any tamper signals sent by your sensor while you are replacing your battery. The tamper signal prevents unauthorized people from tampering/removing/damaging your sensors with the result of that zone becoming a vulnerability within your security system.

Placing your alarm in TEST mode lets the system know that you are testing or performing maintenance on the system so signals won’t be sent to your alarm monitoring company.

3. Take The Cover Off Of Your Sensor

On the bottom of your sensor, you’ll notice a very narrow “slit” or opening. This opening allows you to carefully insert a small screwdriver to pry off the cover of your sensor. Insert your small screwdriver and with a simple twist, the cover will pop off.

The cover isn’t connected to the mount of your sensor so it will be a solid, separate piece that you can set aside until you’re ready to replace it.

4. Remove The Old Battery & Insert New Battery

Using your small screwdriver, carefully remove the existing battery. Keep note of the polarity (the “+” and “-” ends of the battery) and put your new battery in using the same polarity orientation.

5. Replace Cover

Now that the new battery is in place, you can now replace the cover you removed earlier. You should hear a “snap” as it closes, letting you know that the cover is securely back on the sensor.

6. Activate The Transmitter

To activate your transmitter, open and shut your door or window a few times until you hear your keypad beep 3 times each time you open your door or window. If your keypad is too far away for you to hear, or is in another room, recruit someone to stand near your keypad so they can let you know if the keypad beeps.

7. Take Your Alarm Off of TEST Mode

After you’ve got your sensor activated, take your alarm off of TEST mode by entering your user code plus the number 1. You’ll note that the number 1 has the word “OFF” on it. Enter your 4 digit user code again, and again press the number 1. Now, you should no longer see the “LO BAT” signal on your keypad.

Additional Notes:

The battery you should use is a CR123A 3V Lithium Battery that you can pick up at Batteries Plus in Charleston.

Dean Rommes
Dean Rommes

Dean Rommes is the founder and owner of Charleston Security Systems. He has been working in the home and business security industry for over 18 years and specializes in video surveillance technology and cutting edge alarm monitoring services. Dean is a security fanatic and prides himself on giving his clients personalized service any time they need it.