Every time we begin and end Daylight Savings Time, as the battery manufacturers would like you to think is necessary, even though those batteries last 2 years and more? Even though the detectors have ways to test battery viability? Do you recycle those batteries and their toxic components? How many tons of heavy metals go needlessly into the waste stream when we "fall back"?

You don’t have to replace them twice a year, just test them (by pushing the test button on your detector). There are ten year batteries available, then you just test it every six months and you should only have to replace the batteries every ten years or so. A lot less heavy metal waste.