It's two o'clock in the morning, and you hear a chirping noise. You got looking for it, and finally realize it's the smoke alarm. Your replace the battery, and you think you've fixed it, but it keeps chirping. Because it's the middle of the night and you dare not call your electrician and you don't feel like going to the store to buy new 9v batteries, you go to The Google and quickly learn that, upon replacing the battery, the alarm might need to be re-set to stop it from chirping. The reset procedure will vary depending on the make/model of your smoke alarm, so you might look it up now rather than at 2 am when it next happens. Essentially, though, here is the generic reset procedure:
* Turn off the power to the smoke detector at your circuit breaker.
* Remove the detector from its mounting bracket and unplug the power supply.
* Remove the battery from the smoke detector.
* With the battery removed, press and hold the test button for 15-20 seconds.
* Replace the new battery in the detector and plug in the power supply.
* Restore power to the circuit breaker.
* Reattach the breaker to mounting bracket.
Alternatively: If that doesn't work, go to the hardware store or Amazon and buy a new unit, which will cost between $10 and $30. Be sure you get one that includes adaptors or buy adaptors which are a couple of bucks and will save you a trip back to the store.
If neither of these alternatives work, and if your unit is more than 3 years old there is a very good chance they won't (because the problem is likely the result of dust or old age), you at least now know how to take the alarm off your home's grid, so the chirping will stop while you call your electrician.