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Comment by ineedasername | Hacker News Reader

Seems like it's the sort of thing that's borderline useless right up until the moment it's absolutely essential.

Like the smoke alarms in my house, which are actually wired up to mains so don't technically need a battery, but they still have to have a battery in them and will give high pitched chirps ever few minutes when the battery is dead. And since there's so many in the house, and the chirp only comes every few minutes, it's a PITA to find the exact one that needs replacing.

So annoying, and again it's wired to mains so it worked without batteries! Except in a fire the fire might fry the house's magic box of energy delivery leaving only the batteries as the power source and then I really really really want them to work.

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I've had way, way, way, too many 'chirp' at 4am situations in my life. The alarms have _literally_ trained me like Pavlov's dogs that it is _always_ a false alarm, to the point where my sleep deprived brain stumbles through the door blindly into the hallway without even checking if there's heat or smoke.

Some of the other solutions here like cry wolf only if battery low _and_ power's out, or a dedicated LED to indicate a problem, or the one I keep thinking of; gently _saying_ there's a problem with a small sound clip of "bat" instead of an angry Chirp that must wake someone up would really help. The alternative that I've heard many others take is to just disable them entirely if you're in a rental. I'll admit that I've been very tempted to do just that for individual alarms which are overly sensitive to bathroom steam.

> gently _saying_ there's a problem with a small sound clip of "bat" instead of an angry Chirp

Those do exist! At least one smoke detector in my house has voice (primarily to differentiate between smoke and CO alarms)

I started replacing the batteries in all of them as soon as the first one starts beeping.

I figure the batteries won't last much longer in the others and I don't need to go hunting.

We recently had a house burn in our neighborhood during a power outage that was running on a generator. Generator itself caught fire, so pretty much would cover that exact situation.

Yes, it wasn't like this in my house until some years ago when we had a small expansion constructed and the contractor installed these in the new portions just as a standard thing he does, and said he was retro fitting the rest of the house that way too. ( We know him, friends, so we know he wasn't just trying to get extra $ out of us)

For a few minutes I thought it seemed a needless detail, until I realized that often enough people forget to change their stand-alone unit batteries and maybe deal with the the occasional chirp in an "I'll get to it" mindset until it runs down completely. Having it tied to the mains solves that because it's relentlessly annoying to hear that chirp at random intervals, and the battery is a nice backstop failover from the mains going unexpectedly molten.

I mean, it is code now to have them hardwired up. Actually, I think the requirement might be for interconnectivity rather than mains power. It's probably both in some areas. It's quite possible, depending on the extent of your expansion, that he was required to retrofit all of the smoke detectors in the home.

Interconnectivity is separate from mains (though both may be required) - the modern ones have to be set that if ONE goes off, ALL go off.

For those playing at home, get the ones that are BOTH ionization AND photoelectric: https://www.nfpa.org/Public-Education/Staying-safe/Safety-eq...

I wish those mains-powered ones would just shriek continually if the battery was low AND mains power failed; then you could kill the breaker and find it easily.

I wish they just had a steady LED from the mains power on them when the battery was dead. Seems much easier to me.

Yeah, I bet one somewhere has it, but most just flash-when-chirp which is kinda annoying:

This alarm has a low/missing battery monitor circuit which will cause the alarm to “chirp’” approximately every 30 - 40 seconds for a minimum of seven (7) days when the battery gets low. The chirp will be accompanied by a flash of the Safety Light. Replace both bat- teries when this condition occurs.

Some of the newer ones come with a built-in Lithium battery that supposedly is good for 10 years.

Your analogy is way off. If smoke alarms worked like NOTAMs, they’d go off every time someone strikes a match, lights the fireplace, turns on the gas cooktop, uses a hair dryer, or plugs in any appliance. Oh yes, when the house is on fire too. All have non-zero risk of inferno.

NOTAMs are full of pages and pages of goop — inconsistent, impossible to accurately filter, hard to read, at times unclear, and mostly noise.

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