I finally got around to installing smoke detectors in the kids' rooms on Saturday, and I read something I didn't know: smoke detectors are only good for 10 years. After that, you should throw them out. As we have a 40-year-old house and the previous owner was something of a penny-pincher, I'm assuming ours are at least that old.
Also, you can now buy lithium-powered sealed detectors whose batteries will last 10 years, and then you throw them out. They're $20 at Home Depot, and they're one less thing I have to worry about. Just one more thing to worry about during the holidays, yes, but you might want to take a few minutes to replace your detectors. At worst, you'll lose less than an hour of your time, and at best, you will have prevented someone's premature death. Maybe even your own!
Do they have the same thing in CO detectors?
I haven't seen a lithium-powered CO detector, but I've only shopped for them at Lowe's and Home Depot. I was stuck buying the Duracell-powered ones.