I'm a week late on this message but here goes anyhow.
We all hear the news that says "When you change the clocks, change the
batteries in your smoke detectors". That means they are changed twice
a year. I am not going to disagree, even though I only change mine
once a year, which is in fall around the time change. Anyhow, having
fresh batteries in the detectors is a great idea whether it's once or
twice a year. Safety is most important.

On the other hand, there is another issue and that's doing our part to
reduce pollution, and betteries do pollute. My point is this.
Batteries in smoke detectors do not get any use, unless the detector
is beeping all the time from a bad cook, fireplace, or some other
smoke. If the beeper never goes off, those batteries are darn near as
fresh as the day you bought them. Even if time does drain a small
amount from them, if they were newly stocked in the store and put in
your detector 6 months ago, they are likely not beyond the expiration
date.

THerefore, DO NOT toss them in the trash. Put fresh ones in your
detector, but use the old ones on a pocket radio or some other device
that needs the square 9volt batteries. In other words, use them up
before you toss them. Some people might know this, but I know for
fact that others do not. My own elderly mother buys new ones when the
time is changed and has me install them. Then she tells me to toss
the old ones in the trash. Instead I take home all 4 of them from her
4 detectors, and can probably power my portable weather radio for the
next 6 months. Using her detector batteries, and the ones from my own
detectors, I never have to buy batteries for my weather radio, and may
have a few spares too.

Dont toss em' use em..... Smoke detectors are critical and should get
new batteries, but for a pocket radio or other small electronic
device, who cares if they dont last long as long as they get used
before they enter the landfill.

Alvin