You should replace your smoke detector batteries at least once a year. A good time to remember this would be when you set your clocks ahead or back in the spring/fall. If your smoke detector is chirping once a minute or so, you should replace the battery and if that doesn’t help then you may need to replace the smoke detector.
Studies show that 96% of homes do have smoke detectors, but up to 19% of them have missing or dead batteries resulting in hundreds of needless losses and fatalities each year. It is recommended to test your smoke detector once a month.
Replacing your battery
Open battery tray which is usually located on the side of the smoke detector, and remove old battery.
Insert new battery making sure that the (+)(-) are lined up correctly, close battery tray.
At this point you can use a vacuum attachment tool and use it to remove dust/debris by running it over the vents on the detector.
One last thing is to test the detector by pressing the detector test button. Make sure to repeat steps for all your smoke detectors.
Now that you are familiar with the steps, if you know anyone who may not be able to replace batteries such as elderly or disabled people, you could consider offering your help.