Why does my smoke detector go off when I install a battery or turn on the AC power?

It is normal for the smoke alarms to go off and sound briefly (up to 5-10 seconds) when you install a new battery or they are powered up. If the alarm continues to go off and no smoke is present, the cause may be:

  • There may be insufficient battery power. Try another battery.
  • Problems with voltage or insufficient electrical power (brown out) may cause a continuous weak sounding alarm. For AC or AC/DC models, temporarily disconnect power at the service panel until the brown out is over. If you do not restore the AC power, your smoke alarms cannot warn you of a fire.
  • Incompatible warning device. If an incompatible alarm or auxiliary device is linked into a series of AC or AC/DC smoke alarms it may cause the system inadvertently go off.