Replace the batteries

How to Replace the Batteries in Your Smoke Alarm

A house fire is a serious hazard. Many deaths occur from fires at night, in homes with no smoke detectors or one that doesn’t work. Maintaining your smoke alarm can significantly reduce your chances of dying in a house fire. Learn more about how to maintain your smoke alarms to protect your life and property.

Replace the battery

Check the battery type.

Installing the new batteries incorrectly or using the wrong type will result in your smoke alarm not working. Always make sure you use the correct type of battery and install the batteries correctly to ensure the detector works. Smoke detectors with lithium batteries last ten years. You generally can’t replace the battery, instead, replace the entire smoke alarm when it reaches its ten-year lifespan. Many detectors use a 9V battery. However, some may need other batteries. Use good, long-lasting batteries. Using rechargeable or inferior batteries can cause your smoke alarm to fail.

Remove the smoke detector.

You will need to remove the smoke alarm from the ceiling mount. If your detector is hardwired to your home’s electrical system, you should first turn off the power at the fuse box. The method you use to remove your smoke alarm from its mounting depends on the model. Most smoke alarms are removed from the mount by twisting or sliding the detector away. Some detectors do not require you to remove the entire detector. With these models, you only have to remove the part that covers the internal components and the battery. Not all hardwired smoke alarms have a battery backup.

Open the battery compartment and insert the new battery.

To access the battery, you will need to remove the cover that it lies under. Exactly where the battery is located and how it is attached varies by model. You can easily see the battery’s location once you remove the detector cover. The location of this cover also varies by model; some may be attached with a screw or other fastener. Most covers slide off the body of the smoke alarm. Once open, you can take out the old battery or batteries. Make sure you insert the new batteries correctly. Check that the positive and negative terminals match the markings on the smoke alarm. Close the battery cover. Consult the smoke alarm manual if you have trouble locating or removing the battery. If you don’t have an owner’s manual, you may be able to find it on the manufacturer’s website online.

Test the batteries.

Before you reinstall the smoke alarm, you will want to make sure the batteries are working properly. Find and press the button on the smoke detector that tests the batteries. The location of the test button varies. Most test buttons require you to press them for a few seconds to activate the test. If the test is successful, the alarm will sound.

Check again if the test fails.

If the alarm doesn’t sound during the battery test, you’ll need to check them again. Never reinstall your smoke alarm if it has failed the battery test and is shown to be working properly. Check that the batteries are inserted correctly. Make sure the positive and negative terminals match the terminals in the smoke detector. If the batteries are installed correctly, and the test fails, replace the batteries and try again with new ones. If new batteries don’t work, the detector may need to be replaced. You may want to contact the manufacturer, as they may replace it if it is still under warranty. Some alarms have an LED light that shows if the alarm is working properly. Generally, a green light indicates the alarm is working properly, a red light indicates a problem.

Read your smoke alarm’s manual.

If you still have the instruction manual, read the information to better understand your smoke alarm model and to properly maintain its functionality. The location of the battery and how you access it may vary by model. The manual may also state what type of battery your smoke alarm uses. Don’t throw away the instruction manual. Keep it in a place where it is safe and you can access it when needed.

Why are smoke detectors necessary?

Install a smoke alarm to protect your property and life.

By installing a smoke alarm and keeping it working, you increase the likelihood of saving your property and life in the event of a fire. You’re taking an unnecessary risk if you don’t have a working smoke alarm. You risk losing your property by 57% if you don’t have a working smoke detector. You’re 26% more likely to get injured if your smoke alarm isn’t working. If you don’t have a smoke detector installed, you’re four times more likely to die in a fire. There was no smoke alarm in three out of four deaths from a house fire. A properly working smoke alarm reduces the chance of death from a house fire by 50%.

Learn about the different types of smoke alarms.

There are two main types of smoke detectors, each detecting a fire using different methods. You should install both types in your home or find a model that combines both. These two types are based on photoelectric and ionization. Photoelectric detectors use light to detect smoke, while ionization sensors use radiation sensors to detect smoke. Some smoke detectors combine both properties. There are special smoke alarms for the hearing impaired. These generally use a bright, flashing strobe light instead of an audible alarm. Certain smoke detectors can communicate with each other. If one is triggered, all detectors will sound the alarm.

Know the cost of smoke alarms.

A smoke alarm is a great investment and many types of smoke alarms are affordable. If you need to replace old detectors or install new ones, knowing the price upfront can help you plan. Photoelectric or ionization-based smoke detectors typically start at around $6. Models that combine both starts at €24. Some detectors have a microprocessor for better and faster detection, starting at €30. Wireless smoke alarms start at €40.

Learn where to place smoke alarms.

You may have smoke alarms installed in your home, but they may not be in an ideal location. Strategically placing your smoke alarms increases their functionality and allows them to warn you earlier in the event of a fire. Install at least one smoke detector on each floor of your home. Bedrooms should have smoke detector. Each hallway leading to a bedroom should have its smoke detector. Most smoke alarms should be mounted on the ceiling as smoke rises. If this is not an option, mount the detector as high on the wall as possible. A professional electrician should install any directly wired smoke alarm to avoid incorrect installation.

Service your smoke detector.

Having a smoke alarm installed is the first step in fire safety. You must properly maintain your smoke alarm to ensure it protects you. Conduct regular checks and replace batteries regularly to ensure your protection. Test a regular smoke alarm with a 9V battery monthly, and replace the battery annually and the detector every ten years. Test a detector with a long-life battery monthly and replace the detector according to the manufacturer’s instructions. Most were built to last ten years. Test a detector wired directly to the home electrical system monthly and replace the detector every ten years. Replace the backup battery at least once a year. Dust or vacuum your smoke alarms to keep them working at their best.


Some detectors will alert you with an alarm when the battery needs to be replaced. If your smoke alarm goes off with no smoke, the battery may need to be replaced. Even though your smoke alarm is wired directly to a power source, many still have a backup battery that needs to be replaced annually. It can be a good idea to replace your batteries whenever the clock changes to daylight saving time.


Never forget to change old, dead batteries. Never remove the battery or disable your smoke alarm. If it’s triggered by something normal like cooking, improve ventilation in the kitchen or relocate the smoke alarm. Never test your smoke alarm by holding a flame or cigarette against it.


About the Author


Elizabeth Matthews

Elizabeth Matthews is a New York City-based freelance writer who covers a wide range of topics, including business, personal finance, SEO, and life hacks. Her work has appeared in Money, SavingGuru, Forbes, ABCNews, and