My smoke detectors have been chirping for a while. I checked the 9v battery with the multimeter to see if they died. Nope, still good
I checked the detector's sticker on the back and saw it was made in 2003. They're 20 years old now and I guess no longer good. So, I ordered a new pack of hardwired interconnect detectors.
If you're buying now, make sure to get UL 217 8th edition standard in whatever brand you get.
Not only are they much less likely to give false alarms, they are better at alarming earlier at detection of real fires. source
Warning for the USA: while the new UL 217 8th edition standard are on sale, the law allows retailers to sell through their stock of the old ones. You'll still get a working smoke detector, but you'll be missing out on this new better technology/standard.
You have shamed me into installing all new detectors. I know that the internals fade and stop working right after about 10 years...I'm 20+ years in my house. This weekend is smoke detector changeout week - thanks for nothing, friend - now my Saturday is shot ;)
Get the optical triggered versions without the radioactive americium. The old cheap americium type seem to be getting insufficient americium which causes them to go off randomly, prematurely, or for every little VOC increase. I assume it is deregulation based criminality at the heart of the issue. Can't trust anything any more.
The old americium's went off randomly at night and at the mention of bacon... at the grocery store... The new optical ones we have are sensitive to heated aerosols like hairsprays plus hair dryers.
I got google nests in all rooms. They are nice, interconnected, checks itself regularly, gives me the ability to just click it to mute in case I fucked up the fireplace or something but I know
I just changed all mine, got some that come with a remote to silence them. They'll all go off, you press the button once and they all turn off except for the one that triggered it. You press again to turn it off.