Smoke Detector Battery - The Joke Is On Me

[Walt34]

When mine go off they all go off so there's no telling which one has the dead 9v battery. So the only 2:00 AM solution is to remove the battery on all of them, turn off the breaker for the smoke alarms, then wait five-ten minutes for their capacitors to drain and stop the chirping. Don't ask how I know this.

BTW, the reason that the wee hours is their favorite time to go off is that most people turn the heat down overnight. When the battery is just about dead but not quite there yet, that reduction in temperature is just enough to reduce the voltage enough to set off the chirping.

 

[cbo111]

I had one go off during the peak of hurricane Ian. Winds were howling about 80mph. We were sitting around trying to maintain a calm sanity, when suddenly I hear a voice yelling "Fire, Fire, Fire." A smoke alarm was going off. I didn't even know the thing talked. I didn't smell smoke and decided it was not an emergency. So I dragged the ladder in from the garage and tried to reset. Naturally the squawking alarm is on the ceiling of the highest point in the front hallway, so I could barely reach it. No joy with a reset. Changed the AA batteries. Still yelling at me. So I removed the whole device to silence it. I may replace it or might not. My home has 8 fire/CO2 alarms which seems a bit excessive.

 

[imnontrad]

I heard recently that smoke detectors actually should be replaced every 10 years because the sensors wear out. How old is that alarm?

 

[vdesalvo]

Google Nest

Replace your detectors with Nest brand. Automatic self test ever month and sends you the information. When the battery expires (10year) it is time to replace the unit. Remember sensors have a life span.

 

[Jerry1]

I heard recently that smoke detectors actually should be replaced every 10 years because the sensors wear out. How old is that alarm?

That is my understanding as well. It seems tied to the battery, but I don’t think the sensors last indefinitely.

 

[FI_RElater]

half life of isotope limits useful life

That is my understanding as well. It seems tied to the battery, but I don’t think the sensors last indefinitely.

As I mentioned upthread, ionization detectors use Po 210, which has a half life of 158 days. Only a small amount is put into the detectors; the alpha particles emitted are somewhat higher energy (and thus are effective in creating charged particles of anything from the fire source) but are non-penetrating (so don't create a hazard outside the plastic housing). There does need to be some effective amount to be useful; at some age (again, defined by the half-life) the detectors are depleted beyond any ability to create charges and thus can't detect an active fire. [ even replacing batteries at that point would be ineffective, but obviously if the battery was fully discharged it wouldn't be effective either]

 

[38Chevy454]

Another thing to do that helps your detectors, blow them out with compressed air or from a "duster can" type thing. Might have been mentioned back in replies? Dust builds up and can cause a false alarm, or can decrease sensitivity. Helps to extend the detector life some. But as mentioned, the detectors do lose sensitivity from radioactive decay and need replacement after many years. 10 years is a good schedule.

 

[Sunset]

Replace your detectors with Nest brand. Automatic self test ever month and sends you the information. When the battery expires (10year) it is time to replace the unit. Remember sensors have a life span.

At ~$115 each, these are pricey and considering a need 4 or 5 for the house, I'd rather buy the 10 year sealed battery ones for $15 made by First Alert, a company that has been making them for decades.
A savings of $400->$500.

 

[braumeister]

At ~$115 each, these are pricey and considering a need 4 or 5 for the house, I'd rather buy the 10 year sealed battery ones for $15 made by First Alert, a company that has been making them for decades.
A savings of $400->$500.

I agree. Where I live, the code requires two for each bedroom (one just inside the door and one just outside). Then most people want them in other places as well, so the number can easily expand beyond that.

 

[steelyman]

I’ll be buying another of those 10-year First Alert detectors but for carbon monoxide, not smoke. My existing smoke alarms are wired w/9V batteries, ceiling-installed.

I was advised to not get the combination smoke/CO models because CO disperses more evenly in the room space (unlike smoke).

 

[Graybeard]

I’ll be buying another of those 10-year First Alert detectors but for carbon monoxide, not smoke. My existing smoke alarms are wired w/9V batteries, ceiling-installed.

I was advised to not get the combination smoke/CO models because CO disperses more evenly in the room space (unlike smoke).

I don't understand why they'd combine smoke and CO in the same device. Smoke is hot and rises, CO is heavier than air and sinks. Put them on the ceiling and if CO collects to get that high you died a week ago. Put them near the floor and the room would need to be filled with smoke. I don't see how a combination device would work properly vs a smoke detector on the ceiling and a CO detector close to the floor and ignition source.

 

[ERD50]

I don't understand why they'd combine smoke and CO in the same device. Smoke is hot and rises, CO is heavier than air and sinks. ...

That didn't sound right. You might be thinking of CO2 (Carbon Dioxide)? CO (Carbon Monoxide) is lighter than air. A quick search verified that.

https://cpisecurity.com/blog/is-carbon-monoxide-heavier-than-air-and-other-faqs/

Carbon monoxide is also known as the “silent killer” since it’s an odorless, colorless, and tasteless gas. It’s slightly lighter than air but not enough to rise to the ceiling in a room. Instead, it tends to disperse itself, mixing with the air and spreading throughout a space.

These traits are what make CO so dangerous: it’s a poisonous, invisible gas that is undetectable to the nose or eye (hence the importance of CO detectors), and mixes into our normal safe air.

-ERD50

 

[RobbieB]

Yeah, lighter than air, should be mounted 2/3 - 3/4 to the ceiling.

 

[Graybeard]

That didn't sound right. You might be thinking of CO2 (Carbon Dioxide)? CO (Carbon Monoxide) is lighter than air. A quick search verified that.

https://cpisecurity.com/blog/is-carbon-monoxide-heavier-than-air-and-other-faqs/


-ERD50

Yeah, lighter than air, should be mounted 2/3 - 3/4 to the ceiling.

I'm shocked! I did Google this and you are right.

Here's the odd thing about this. When I walk out of the basement into the garage there is a drop of about 4-5", this was new construction and I wondered why both floors were not at the same level. I asked why and was told CO is heavier than air so any CO from the boiler just a few feet from the door into the garage or the cars would sink into that lower area. Now I wonder if it was in case the garage was flooded the water had to rise before it got into the basement.

I guess I better move my CO detector from about 8" off the floor to about 5-6' onto the shelves above!

 

[Telly]

I thought garage floors were lower, or curbed from the doorway into the house, to keep gasoline from a leaky gas tank from running into the house.

 

[CaptTom]

I thought garage floors were lower, or curbed from the doorway into the house, to keep gasoline from a leaky gas tank from running into the house.

Or more to the point, gasoline fumes, which are heavier than air.

 

[ERD50]

I'm shocked! I did Google this and you are right.

Here's the odd thing about this. When I walk out of the basement into the garage there is a drop of about 4-5", this was new construction and I wondered why both floors were not at the same level. I asked why and was told CO is heavier than air so any CO from the boiler just a few feet from the door into the garage or the cars would sink into that lower area. Now I wonder if it was in case the garage was flooded the water had to rise before it got into the basement.

I guess I better move my CO detector from about 8" off the floor to about 5-6' onto the shelves above!

Maybe not related, but propane is heavier than air (Natural Gas is not). This makes propane leaks very dangerous, as they concentrate in a 'pool' rather than rising and dissipating through chimneys, vents, etc.

-ERD50

 

[Koolau]

Chirp, chirp, chirp ... the battery is going low on my smoke detector/carbon monoxide and smoke detector that are hard wired, yet require batteries as backup.

I have on in the hallway, and one in the adjacent bedroom. Same brand detectors.

So I open the battery holder on one, see that it takes two AA batteries. I run to the store and buy 4 batteries, figuring, might as replace for both detectors.

But to my surprise, when opening the holder for the other detector, it takes a 9V smoke detector battery .

What the heck? Why couldn't they just use the same size batteries?

My smoke detector batteries are "irreplaceable!" The unit is guaranteed for 10 years - then you pitch it and buy another. I assume they use lithium long-life batteries of some kind. Couldn't even get into it (without a hammer) so I am trusting that it will last. It comes with a place to write down the date it was activated. So my quarterly check (you know, push the button and hold your ears) includes looking at the back to check the date. Have a couple of years left. IIRC the cost was NOT outrageous. NOT needing to change batteries every year or two is kinda nice. YMMV

 

[ncbill]

From what I've read all new detectors even the ones with replaceable batteries are set to self-destruct (continuous beeping even after battery replacement) a decade after first activated.