A question came up in the family: Many smoke alarms these days come with a 10-year battery. We know conventional batteries typically corrode in a year or so. Do these 10-year batteries also corrode in the same time as a conventional battery? Apparently not, I wager, but if not…why not?
It may simply be that they are sealed better and won’t leak or corrode as quickly. I’m guessing you pay more for the 10-year battery.
IME conventional alkaline batteries don’t “typically corrode in a year or so.” I think they tend to corrode if they are exposed to harsh environments, which would not include the inside of a modern house.
Most 10-year batteries are Lithium Thionyl Chloride, and they are manufactured with a glass seal, so they rarely leak.
I think your battery knowledge might be 50 years out of date …
Alkaline 9v batteries have a roughly 5 year storage life, and are good for roughly a year in a smoke detector.
The 10 year batteries are almost certainly lithium batteries of some stripe- I sort of doubt they’re just regular old Energizer Lithiums- they’re probably quite a bit larger to support 10 years of use. The trick to the 10 year battery smoke detectors is that the detectors themselves have a 10 year service life as well- if they make them have a 10 year battery, then you kind of kill two birds with one stone- the consumer replaces the detector when it is necessary AND there’s no need for them to replace the battery annually. Win-win, even if it costs a bit more up front (but it’s for 10 years of use, so how much is that extra cost actually?)
But fundamentally, they use a different battery chemistry that doesn’t involve the outer shell like the older zinc-carbon did (the batteries notorious for leaking), so they’re going to be fine for that duration.
I have a cheap wristwatch around somewhere that’s 20 years old, never had the battery replaced, and still works (though the numbers are rather faded). The only reason I don’t wear it any more is the band didn’t last nearly that long.
I just returned 2 2-packs of smoke alarms to Costco supposedly with 10 year non-replaceable batteries. They all started a low battery chirp (at 3am of course) after 1 year.