Quick Answer
How to change battery in a smoke alarm: twist or slide the alarm off its base, swap in the battery type the alarm specifies, refit it and press the test button until it sounds. That stops a low-battery beep. A sealed 10-year alarm has no replaceable battery, so replace the whole unit, as you should with any alarm after 10 years or its replace-by date.
Key Takeaways
- Check which type you have before opening it. Replaceable-battery alarms need a new battery, while sealed 10-year alarms must be replaced whole.
- Fire and rescue services disagree on testing: weekly (Scottish Fire and Rescue Service, Nottinghamshire) or monthly (Devon and Somerset, Hampshire and Isle of Wight). If unsure, the more frequent check is the more cautious one (our reading).
- Tenants in England are advised to replace batteries themselves and to report an alarm that still fails, because landlords must repair or replace faulty alarms once told.
This is safety advice, so it comes from UK fire and rescue services, the National Fire Chiefs Council (NFCC) and government guidance rather than from product blogs. We have not tested any alarm ourselves. Alarms differ by make, so your manual always takes priority over a general guide.
Why it chirps
Smoke alarm beeping: what the sound means
Smoke alarm beeping every minute or so is usually a low-battery warning. Devon and Somerset Fire and Rescue Service says to confirm the alarm is the source first, because smoke, carbon monoxide, gas and burglar alarms can all beep. Hard-wired alarms plug into the mains but still have a backup battery, so they can give the same warning.
The services give different deadlines. Devon and Somerset says to replace the battery or alarm promptly, “certainly within seven days”. Hampshire and Isle of Wight says a sealed alarm with a low-battery warning needs replacing and should keep working for about two more weeks. Do not wait for the end of either window.
Pressing the central test button can silence the low-battery warning, and the alarm will still detect smoke, according to Devon and Somerset. FireAngel’s troubleshooting guide (published through Staffordshire Fire and Rescue Service) adds that a low-battery chirp can only be silenced a maximum of 10 times, and that a red light flashing at a different time from the chirp signals a fault, so the alarm should be replaced.
Why it keeps beeping after a new battery
Nottinghamshire Fire and Rescue Service says intermittent beeping can mean the alarm needs replacing, and that temperature changes and dust can also trigger chirping. FireAngel says dust, dirt and humidity can cause unwanted alarms and to clean the alarm if it sounds with no smoke. Aico’s guidance (reproduced on a retailer’s blog, dated 2011) says to check the alarm is fully seated on its base and press the test button. If it still beeps, the sources give no further steps beyond contacting the maker or supplier.
Battery types
Check the label or the manual before you buy a battery.
| Type | What to do | Source |
| Replaceable battery (such as a 9V) | Change the battery once a year | Devon and Somerset, Hampshire and Isle of Wight, Scottish Fire and Rescue Service |
| Hard-wired with backup battery | Follows the manual; low-battery warning can still sound | Devon and Somerset, Aico (2011) |
| Sealed 10-year battery | Do not open it; replace the whole alarm at the end of its life | Hampshire and Isle of Wight, Nottinghamshire, NFCC |
Nottinghamshire recommends 10-year sealed alarms and says to buy ones marked with the British Kitemark and BS EN 14604: 2005. The NFCC’s position statement (June 2019) recommends a sealed battery compartment to prevent tampering, an optical multi-sensor alarm with a ten-year life, and interlinking where possible so all alarms sound together.
Use the battery type the alarm specifies. Aico’s 2011 guidance warns that other batteries may cause problems. Never take the battery out for another device. A Shropshire Fire and Rescue Service page (dated 2013) says not to use alarm batteries in remote controls or toys.
Step by step
This is how to change battery of smoke alarm models that take a replaceable battery. It also covers how to change the battery on smoke alarm units that are hard-wired with a backup battery.
How to change battery in a smoke alarm
Follow your alarm’s manual if it differs from these steps.
- Check the type. If it is a sealed 10-year alarm, do not try to open it. Replace the unit.
- Make sure the beeping really comes from the smoke alarm and not another device (Devon and Somerset).
- For a hard-wired alarm, Aico’s guidance says to switch off the circuit labelled for smoke alarms at the consumer unit first. That guidance is from 2011, so check your manual, and use an electrician if you are not sure.
- Take the alarm off its base (see the next heading).
- Remove the old battery and fit the specified type.
- Refit the alarm to its base.
- Press the test button until the alarm sounds.
You may need a stepladder, or a helper to hold it steady, as Devon and Somerset notes for cleaning alarms.
How to open smoke alarm to change battery
How to open smoke alarm to change battery varies by model. FireAngel’s guide says to remove the alarm by twisting it anticlockwise from its base, and to turn it fully clockwise to refit it so it sits securely. Aico’s guidance describes a different design: put a small flat-bladed screwdriver about 1cm into the removal slot, keep it parallel to the ceiling, and slide the bottom half of the alarm sideways off the base-plate. Do not force it. If neither matches your alarm, use the manual or the maker’s support line.
How to remove battery from smoke detector
How to remove battery from smoke detector depends on the design. In Aico’s guidance, the battery unclips from snap connectors once the alarm is off its base. The government’s smoke alarm advice (12 January 2016) says: “Whatever happens, never remove the battery in your smoke alarm unless you are replacing it.” The Scottish Fire and Rescue Service says never to remove batteries, even briefly.
How do you change battery in smoke alarm in a rented home?
If you rent in England, the government’s guidance for landlords and tenants (updated 29 July 2022) says tenants are advised to replace the batteries if an alarm stops working, and to report the fault to the landlord if it still does not work. Landlords must ensure alarms are repaired or replaced once informed that they are faulty. It also says at least one smoke alarm should be installed on every storey used as living accommodation. We did not check the rules in Wales or Northern Ireland.
Testing it
Press the test button until the alarm sounds. The services give different intervals.
- Weekly: Scottish Fire and Rescue Service and Nottinghamshire.
- At least monthly: Devon and Somerset and Hampshire and Isle of Wight. The government’s 2016 press release also says monthly.
- Regularly, with no interval: the NFCC position statement.
Scottish Fire and Rescue Service says that if an alarm does not sound, replace its battery, and if it still does not sound, replace the alarm.
For cleaning, Devon and Somerset suggests vacuuming or dusting the alarm every three months to reduce false alarms. The older Shropshire page says twice a year. To pause a false alarm, Devon and Somerset says to press and release the central test button, and the alarm returns to full sensitivity within 10 minutes.
Position matters. Nottinghamshire says to fit alarms on every level, ideally in hallways and landings, at least 30cm from walls and light fittings, and to use a heat alarm in the kitchen instead of a smoke alarm. In Scotland, homes need a smoke alarm in the living room, one in each hallway or landing and a heat alarm in the kitchen, all interlinked, since February 2022.
When to replace the whole unit
Replace the whole alarm after 10 years. Devon and Somerset says “most smoke alarms need to be replaced after 10 years”, Hampshire and Isle of Wight says to replace the whole unit, and the Scottish Fire and Rescue Service says the sensing material inside wears out with age. The NFCC says alarms, including hard-wired ones, should be replaced after ten years, or by the replace-by date on the base if earlier, or sooner if defective.
Check the date printed on the alarm. FireAngel’s guide says to replace one past its date immediately. If you are not sure how old your alarms are, a replacement is the safe choice (our reading).
Alarm replacement can be a good moment to upgrade. Interlinked alarms sound everywhere in the home when one is triggered, which the NFCC and the Scottish Fire and Rescue Service both recommend or require.
Frequently Asked Questions
How do I change battery in smoke detector units that have one?
Check it has a replaceable battery, then twist or slide the alarm off its base, fit the specified battery, refit it and press the test button until it sounds. Sealed 10-year alarms cannot be re-batteried and must be replaced whole.
Why is my smoke alarm beeping?
An intermittent beep is usually a low-battery warning, but confirm the smoke alarm is the source. Replace the battery or alarm within about seven days, according to Devon and Somerset. Dust, humidity and age can also cause chirping.
Can I just silence a beeping smoke alarm?
Pressing the test button can silence a low-battery warning for a while, but it is only a short-term fix. FireAngel says it can only be done 10 times. Replace the battery or the alarm promptly.
Can I take the battery out of a smoke alarm?
Only to replace it. The government says never to remove the battery unless you are replacing it, and the Scottish Fire and Rescue Service says never to remove it, even briefly. Do not use alarm batteries for other devices.
How often should I test and replace a smoke alarm?
Fire services advise testing weekly or monthly, depending on the service. Replace the whole alarm after 10 years, or by the replace-by date on it if earlier. A replaceable battery usually needs changing once a year.
Who changes the battery in a rented home?
In England, tenants are advised to replace batteries if an alarm stops working and to report it to the landlord if it still fails. Landlords must repair or replace faulty alarms once told, according to GOV.UK guidance updated 29 July 2022.
