Some smoke detectors run on batteries, which need to be replaced regularly. Some run on your home’s electric current, and won’t work if you lose power. Put both types of detectors in your house to be sure you’re protected.
Not all smoke detectors work in the same way. “Ionization” units are better at detecting fires with big flames. “Photoelectric” units are better at detecting fires that start slow and have more smoke. Both kinds must pass the same safety tests and will work well on all types of fires.
Most smoke detectors sound an alarm, which should be loud enough to wake you from sleep. If you have trouble hearing it, get a detector that comes with a bright strobe light. This light blinks when the detector senses smoke. Place the detector right near your bed so the light will wake you up.
Some smoke detectors shine a bright light every time the alarm sounds. This light helps you see where you’re going. Put one of these detectors near an exit so you can find your way to the door.
Source: AARP
Learn more about smoke alarm safety.