How could smoke alarm beep without battery and disconnected?

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SUMMARY

The discussion centers on how a smoke alarm can beep after the battery has been removed and it has been disconnected from the ceiling. Two primary explanations are provided: the smoke alarm may store energy in a capacitor or it could be connected to the house's electrical supply. It is essential to consult the instruction manual for the specific smoke alarm model, as those powered by an external source typically include a capacitor for backup power, enabling them to emit alerts temporarily during power failures.

PREREQUISITES
  • Understanding of smoke alarm power sources
  • Knowledge of capacitor functionality
  • Familiarity with electrical systems in residential settings
  • Ability to read and interpret product manuals
NEXT STEPS
  • Research how capacitors function in electronic devices
  • Learn about the electrical wiring of smoke alarms
  • Examine different types of smoke alarms and their power sources
  • Review safety standards for smoke alarm installation and maintenance
USEFUL FOR

Homeowners, electricians, safety inspectors, and anyone responsible for smoke alarm installation and maintenance will benefit from reading this discussion.

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It beeped when I had removed battery and disconnected it from ceiling. The power has to come fromm somewhere, so how could it beep?
 
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sp3sp2sp said:
It beeped when I had removed battery and disconnected it from ceiling. The power has to come fromm somewhere, so how could it beep?
Two options:
1. It's storing some energy in a capacitor.
2. It's connected to the house's electricity.

You should look up the instruction manual for it.
 
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A smoke alarm that is usually powered from an external source will have a capacitor for back-up power. That allows it to "chirp" for a while when the normal power fails. That is important for keeping the alarms working.
 

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