Instead of waiting for a smoke detector to jolt you out of bed in the middle of the night with the loud chirping or beeping sound it makes when the batteries begin to die, it makes sense to beat it to the punch by replacing the battery twice a year on a regularly-scheduled basis. A good time to replace all of your smoke detectors' batteries, because it serves as a twice-yearly reminder, is on the weekends when we set our clocks forward  for daylight savings time and back to standard time.

Smoke detectors may be either battery powered or wired directly into a home’s electrical system. But nearly all smoke detectors, including those that run on household current, do contain a battery. Detectors that are hard-wired to the home's electrical system use this battery to provide backup power in case a fire knocks out the house’s electrical power.

Both battery-operated and household-current smoke detectors sound the previously-mentioned beeping or chirping low-battery alarm.

Why we like it: • Two sensors offer optimal protection • Two batteries included • Hush feature silences nuisance alarms

This alarm is different than the deafening, blaring fire alarm that occurs during a fire: it is a sporatic beep, not a constant blast.

If you hear the beeping or chirping low-battery alarm, do not ignore it; change the battery immediately. Do not ever remove the battery without replacing it with a new one--smoke detectors with fully-functional batteries are critical to the safety of your family and home. Sadly, news reports of tragic fires often point out that the home had smoke detectors but those detectors had been disabled.

(Note: New lithium battery models last up to 10 years; the entire unit is disposable. If your home has this type of detector, you will need to replace the entire unit.)

Most conventional smoke detectors have a friction-fitting cover that hinges down or lifts off. With some, the entire body of the smoke detector clips onto a base that is attached to the ceiling or wall. To remove these, you typically give the body a counterclockwise twist.

1. Remove the cover or body. Gently pry the cover open or unclip the body of the detector from its base with a slight twisting motion. Inside, you will find three main parts: the sensing chamber, a loud horn, and a battery (and in some cases, house voltage power source). 

2. Replace the battery. Unclip the old battery from its holder. Most detectors utilize a 9-volt battery--use a brand new lithium 9-volt battery as a replacement. Be sure the male and female terminals are properly oriented. 

3. Close the cover or replace the body. Snap the cover shut or lock the body of the smoke detector back into its base.

4. Test the detector. Press the test button on the surface of the detector to make sure the battery is working. When the button is pressed, the detector should beep or chirp.