Low battery · First Alert · smoke
First Alert: Five chirps every minute, one green flash
Low battery signal. The SM210L’s battery is sealed in for its life, so First Alert’s instruction is to replace the alarm, not the battery.
- What you see
- One green flash about every 60 seconds
- What you hear
- Five chirps about every 60 seconds
If it is sounding a full alarm instead: the maker’s emergency instruction
Smoke alarm
First Alert (SM210L manual): if the alarm sounds, get everyone out of the house immediately — do not stop to dress or collect anything. Feel doors with the back of your hand and do not open a hot one; cover your nose and mouth with a damp cloth; meet at your planned place outside and count heads; call the fire department from outside, giving your address and then your name; never go back inside a burning building.
From User’s Manual — Smoke Alarm, 10-Year Sealed Battery with Escape Light.
The First Alert alarm on these pages senses smoke only. For a carbon monoxide alarm, follow its own maker’s instruction.
What First Alert says to do about this signal
- Replace the alarm immediately.
- Before you throw it away, the manual has you break the tab and slide the activation switch to deactivate mode, which drains the stored battery energy; the unit will not work after that.
From User’s Manual — Smoke Alarm, 10-Year Sealed Battery with Escape Light. If your alarm’s pattern is not exactly this, check the manual for your model: First Alert models do not all use the same signals.
Other First Alert signals
Low battery on other brands
The same state sounds and looks different on each make — which is why a chirp pattern cannot be read without the brand.
Sources
Every line on this page comes from First Alert’s own documents, read on the date shown. Nothing is taken from third-party code sites or other makes.
- First Alert (BRK Brands): User’s Manual — Smoke Alarm, 10-Year Sealed Battery with Escape Light — Model SM210L. support.firstalert.com Checked 2026-09-29.