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How long does a HARDWIRED smoke alarm BACKUP battery last?

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  • Oct 26th, 2020 5:10 pm
[OP]
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Nov 21, 2007
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Scarborough

How long does a HARDWIRED smoke alarm BACKUP battery last?

Searched Lowes/HD for hardwired smoke alarms. Looks like all models have battery backup. Now, if I have to change the batteries every year....doesn't that defeat the purpose of having hardwiring? I might as well buy the 10yr lithium operated ones?

The net search only came up with annual change on battery operated models. Nothing on backup batteries...
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Deal Addict
Feb 11, 2018
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AFAIK, when the battery of a hardwired smoke detector is low the detector will start beeping. At least that's the case with mines. Battery seems to last a few years.
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Dec 28, 2007
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Battery backup for when your power goes out. Mine uses a 9V battery and lasts about 2 years.
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May 23, 2009
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I had three hardwired First Alert combo detectors (SC7010) that worked 7 years on original battery. They were still functioning on original battery when I replaced the detectors a few months ago.
Last edited by bubuski on Oct 21st, 2020 12:35 pm, edited 1 time in total.
Sr. Member
Jun 26, 2019
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On average, depending on a lot of things, I'd say they usually last 2-3 years.

You could just let them start beeping once and then you'll know how long yours last on average.

It should be noted that there is a 100% chance they will start beeping at some hour when you're fast asleep.
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Feb 11, 2018
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SubjectivelyObjective wrote: On average, depending on a lot of things, I'd say they usually last 2-3 years.

You could just let them start beeping once and then you'll know how long yours last on average.

It should be noted that there is a 100% chance they will start beeping at some hour when you're fast asleep.
The beeping is rather mild compared to when the alarm goes off. Also I think it is something like 1 beep per minute. I have four alarms and the batteries all died during the day. Thinking more about it, over the life of my previous alarms (7 years) I only needed to change the battery once per alarm.

How long a battery will last is directly correlated to how often and how long your house loses power. If you almost never lose power then you can sleep easy knowing it will be many years before it needs changing.
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Time will cease to exist when there won't be a soul left in the Universe.
Jr. Member
Oct 19, 2020
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Samwfive wrote: Looks like all models have battery backup. Now, if I have to change the batteries every year....doesn't that defeat the purpose of having hardwiring? I might as well buy the 10yr lithium operated ones?
Kidde has had a lot of issues with their sealed battery alarms - false trips and batteries failing early. I would avoid them.

It's actually illegal to replace hard wired alarms installed to comply with building codes with battery operated.

The greatest benefit is the ability to interconnect with other alarms so if your alarm goes off in the basement you hear it loud upstairs.
Battery also needs to be changed less frequently than conventional 100% battery operated. (yes, you can buy wireless interconnect 100% battery operated alarms, but super expensive and they're intended for retrofit applications with no wiring)

Hardwired units without battery backup don't come close to meeting basic safety standards any more btw - you may be able to buy them still, but horrible idea. If you have an electrical fault on the circuit or power goes out, no protection.
It's important to have both battery backup and interconnection, as well as comply with laws.

When replacing, I do strongly recommend incorporating some photo-electric or dual sensor alarms into the system as ionization ones go off far too late when the smoke is from a slow smoldering fire.
[OP]
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Nov 21, 2007
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Scarborough
Thank you all for responding so far...
insertname2020 wrote: Kidde has had a lot of issues with their sealed battery alarms - false trips and batteries failing early. I would avoid them.
The very reason I'm avoiding batteries.

It's actually illegal to replace hard wired alarms installed to comply with building codes with battery operated.
Hmmm?

The greatest benefit is the ability to interconnect with other alarms so if your alarm goes off in the basement you hear it loud upstairs.
Battery also needs to be changed less frequently than conventional 100% battery operated. (yes, you can buy wireless interconnect 100% battery operated alarms, but super expensive and they're intended for retrofit applications with no wiring)
All of us have good hearing and I have yet to come across battery change frequency from all manufacturers.

Hardwired units without battery backup don't come close to meeting basic safety standards any more btw - you may be able to buy them still, but horrible idea. If you have an electrical fault on the circuit or power goes out, no protection.
It's important to have both battery backup and interconnection, as well as comply with laws.
I just installed 3 hard-wired from Lowes with no-backup. All non-smokers and no power means no fire....99.9% of the time?

When replacing, I do strongly recommend incorporating some photo-electric or dual sensor alarms into the system as ionization ones go off far too late when the smoke is from a slow smoldering fire.
Am with you there, picking up a photo-e one for the basement.
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Feb 25, 2004
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Longueuil
Samwfive wrote: Exactly the same as the ones that I just replaced, HD only has 1 in stock...grrr. Had to settle from Lowes.
I ordered them online for in-store pickup when I changed mine (about a month ago), it took less than a week to have them delivered at the store.
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Jr. Member
Oct 19, 2020
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The most important parts of the house to have photo-electric: sleeping areas!
When you're awake, you'll notice a smoldering fire.

It's the smoke that kills people in their sleep!
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Sep 8, 2007
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Way Out of GTA
insertname2020 wrote: Kidde has had a lot of issues with their sealed battery alarms - false trips and batteries failing early. I would avoid them.

It's actually illegal to replace hard wired alarms installed to comply with building codes with battery operated.

The greatest benefit is the ability to interconnect with other alarms so if your alarm goes off in the basement you hear it loud upstairs.
Battery also needs to be changed less frequently than conventional 100% battery operated. (yes, you can buy wireless interconnect 100% battery operated alarms, but super expensive and they're intended for retrofit applications with no wiring)

Hardwired units without battery backup don't come close to meeting basic safety standards any more btw - you may be able to buy them still, but horrible idea. If you have an electrical fault on the circuit or power goes out, no protection.
It's important to have both battery backup and interconnection, as well as comply with laws.

When replacing, I do strongly recommend incorporating some photo-electric or dual sensor alarms into the system as ionization ones go off far too late when the smoke is from a slow smoldering fire.
You might be referring to this expensive pile of garbage that is well known across the board as the false alarm king. And as one of few to meet code were put in many houses recently. We had these piles of junk false alarming in the middle of the night at an increasing rate.....scaring the crap out of my kids. Finally I’d had enough and ripped all of them out. Kidde to their credit were willing to replace with the same units (but they are still the same unit) so I took ones that are known to work (interconnected combo ones) without the built in strobe. And while may not be “code”...working alarms are better than disconnected alarms or ones going off falsely...

There’s simply something wrong with these units and they know it.
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SubjectivelyObjective wrote: On average, depending on a lot of things, I'd say they usually last 2-3 years.

You could just let them start beeping once and then you'll know how long yours last on average.

It should be noted that there is a 100% chance they will start beeping at some hour when you're fast asleep.
My Kiddes also alert me in a strident voice in between the beeps, in English and French: Pile faible! Low Battery! Pile faible! Ideal to bring you to full alert from your REM sleep.

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