Why is it that smoke detectors always seem to get low battery warnings in the middle of the night?

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My t-stat is set the at the same temp day/night. Not sure a degree or 2 would change the voltage enough to trigger the alarm but maybe if some drop the setpoint 10-15 degrees it could make a difference.
 
My t-stat is set the at the same temp day/night. Not sure a degree or 2 would change the voltage enough to trigger the alarm but maybe if some drop the setpoint 10-15 degrees it could make a difference.
But does yours always start chirping at night?
 
Colder than during the day.

Or maybe people should listen to, you know, the companies that make them.


yeah, I said that...
;-)
Kidding, thanks for the official link.
 
9V batteries are mostly alkaline batteries. All batteries slow down when it’s cold. The new trend(and law in California, Oregon and a few other states) are “sealed” smoke alarms with a “lifetime” battery. Those will use a 3V coin cell or a 1/2 AA cell - all lithium.

Oddly enough, Google’s Nest Protect is CA-legal but it uses 6 AA Energizer Lithium Ultimate batteries that are user-replaceable.
 
When I was in the Philippines we had smoke detectors in the barracks all over. They never went off. We should have had earthquake detectors, they would have been going off all the time.
 
9V batteries are mostly alkaline batteries. All batteries slow down when it’s cold. The new trend(and law in California, Oregon and a few other states) are “sealed” smoke alarms with a “lifetime” battery. Those will use a 3V coin cell or a 1/2 AA cell - all lithium.

Oddly enough, Google’s Nest Protect is CA-legal but it uses 6 AA Energizer Lithium Ultimate batteries that are user-replaceable.
I haven't taken apart one of those 10 year ones yet. I'll do it once they go bad in a few years. I always figured it was a 9v volt battery. I doubt the 3v coin cells put out enough power to last that long. I always liked to replace the battery, they can last 15-20 years. They're probably still good at 10 years but because you can't replace the battery, you'll have to toss them out. The reason they make them non-replaceable is so people don't take the battery out, about 1/3 of fires is from homes where they removed the battery. For the price of a Nest, would make sense you could replace the battery if you got a bad set instead of having to toss the whole thing out. If they include the carbon monoxide alarm, those electrochemical sensors are toast after 7-10 years anyway.
 
I haven't taken apart one of those 10 year ones yet. I'll do it once they go bad in a few years. I always figured it was a 9v volt battery. I doubt the 3v coin cells put out enough power to last that long. I always liked to replace the battery, they can last 15-20 years. They're probably still good at 10 years but because you can't replace the battery, you'll have to toss them out. The reason they make them non-replaceable is so people don't take the battery out, about 1/3 of fires is from homes where they removed the battery. For the price of a Nest, would make sense you could replace the battery if you got a bad set instead of having to toss the whole thing out. If they include the carbon monoxide alarm, those electrochemical sensors are toast after 7-10 years anyway.
I’ve installed a mix of the First Alert(BRK) and Kidde 10 year smokes for two properties my parents owns. I think the Kiddes using the 1/2 cell batteries might have better endurance than the First Alerts. I see a Panasonic battery in those.
All of them except one are photoelectric sensor, one is a combo CO/smoke.

I remember having to fix a friend’s fire alarm at his bike shop - I ended up reusing and cleaning up the existing Chemtronics smokes but I also installed new System Sensor(Honeywell) 4-wire smokes and a Silent Knight Hochiki protocol smoke next to the panel. Talk about fun.
 
I’ve installed a mix of the First Alert(BRK) and Kidde 10 year smokes for two properties my parents owns. I think the Kiddes using the 1/2 cell batteries might have better endurance than the First Alerts. I see a Panasonic battery in those.
All of them except one are photoelectric sensor, one is a combo CO/smoke.

I remember having to fix a friend’s fire alarm at his bike shop - I ended up reusing and cleaning up the existing Chemtronics smokes but I also installed new System Sensor(Honeywell) 4-wire smokes and a Silent Knight Hochiki protocol smoke next to the panel. Talk about fun.
You should see those Gentex smoke alarms, you can actually put in them in a bucket of water to clean them.
 
The new ones do not have replacable batteries. Supposed to last 10 years. Lucky if they last 3.
I've been installing them for the last few years, haven't had any die yet. I put in lithium 9 volt batteries over 12 years ago. A couple of them are still going. Others died after 6-8 years. I think maybe those false alarmed more or just the luck of the draw. Those were in hardwired one so probably not much draw at all in the battery backup mode. I don't bother putting them inside battery operated units in the apartments because half the time the tenants either destroy the smoke alarm or they're missing or they just take out the battery so I'm not going to bother with a $4-$6 battery when it might not make it more than a couple years.
 
Great thread, thanks for the link to Kidde's explanation. Seems weird that they're sensitive enough that a relatively small drop in temperature would cause this but that does seem to be the case.

Where I live all homes built since the mid 90s or so have many smoke alarms, hard wired with battery backup. In my first place almost 20 years ago the first one to go was in the hallway outside the bedrooms, way up high due to the vaulted ceiling. Started beeping in the middle of the night, had no ladder long enough to get up there so I grabbed a broom and a step ladder and smashed it off the wall. Never did replace it :unsure:

Later had one like somebody else mentioned, didn't have a battery on hand and when I took it down and removed the "dead" battery the sucker wouldn't stop beeping. Stuck it in the freezer, did the trick.

Anytime one goes now I use one of those Energizer lithium batteries to replace it. Haven't had one of those go yet.

jeff
 
I use the lithium batteries so I don't have to change them as often. Now the state code requires 10 year battery smoke detectors so I'm slowly phasing out all the old battery ones although the hardwired ones still use regular batteries. And yes, the colder it is, the less power the batteries put out so more likely to happen at night. I change them out for tenants when they start to chirp. I can't believe some of them can put up with it for days/weeks and they don't even say anything, I just change them when I hear them.
My next door neighbor's chirped for 6 months until they stopped it.
 
Colder than during the day.

Or maybe people should listen to, you know, the companies that make them.

I guess it makes sense, but I have hard wired ones and I had one fail at 2AM. It was just a entire unit failure. It was a CO/Smoke detector and it was alerting to CO. The kids didn't even wake up, but we had fire dept come with their tester and said everything was good. I replaced the unit and another did the same about 2 years later, and now the current ones have been good for a few.
 
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