Depending on brand, there is an internal capacitor to keep the circuit
memory. 9 times out of 10 when the units chirp, the battery needs replaced.
However that one time is usually:
A) The unit has gone bad and the radiation has degraded the electronics
enough to cause it to chirp. Found in really old units mostly (+10 years
B) There is cold air getting in to the unit. For some reason I found out
about this after going to a customers home to find out why no matter what
was put in the same location, it would chirp. As soon as I called the
factory, the CSR asked that after I explained what was going on. Some
investigating found an open window (in the middle of winter) near the box.
C) There is a loose connection in the battery.
D) Dirt or dust has gotten into the sensing area. Found in new construction
Put them back up with new batteries and wait. If there is still a chirp,
clean the units with some canned air (not compressor air). Reinstall and
wait again. If it becomes the Energizer bunny, replace the unit that is
still going with the same manufacturer. The recommended interval for
changing the battery is every six months. The manufacturers recomend this
due to the fact a battery becomes weak after sitting idle for more than
that. I change mine on New Years Day and Father's Day. I want to make sure
that the battery doesn't fail when we might need it most.
Also how many people have picked up a can of smoke at a local supply to test
their smoke detectors.
I concur. And it is quite possible the chirping you're hearing now is
just a warning that the alarms are currently without power (either a/c
or battery). I'm betting everything is back to normal if you replace
your batteries and turn the power back on.
Yes the test button does not discharge the circuit internally. The chirp
is a warning that there is NO power to the unit. I was told that it can last
anywhere from 3-5 days. And as a previous poster stated it is a threshold
that when it drops below it.
My wife likes to burn cookies every so often to check ours.
I am an electrician by trade, and the guys in the supply house tell me that
some detectors can chirp for days after being removed from power. Sorry, I
don't have a technical answer, but I have witnessed this myself.
A true story... A large box of "defectivce" detectors were returned by a
contractor. Apparently he installed the wrong model in a multi-family
building, and had to replace the entire lot. These were removed a few weeks
after installation and all the batteries "recycled" (put to other uses) and
this box of detectors was still chirping days after being delivered to the
When the voltage on the internal capacitor drops below a preset
threshold, the Test alarm circuit won't fire, indicating a failure,
ie. low battery. As a result, the Test circuit doesn't discharge the
capacitor completely and leaves enough charge to power the low battery
chirps which keep working for a while below the Test alarm threshold.
On 5 Mar 2007 09:35:00 -0800, email@example.com
Your comment makes sense, but I have a question...
When I hold in the test button the unit emits several tones
of decreasing volume until there is no sound at all.
Are you suggesting that at that point, there is still enough
energy to produce the periodic "chirp?"
Today, I purchased a new detector (same model), installed
it, and within about two hours, it was chirping.
That seemed to leave only the possibility that the AC to
that location was somehow flaky, so I re-wired it.
Still, it chirped.
Then I had another idea...
I called the manufacturer to ask if there were any
conditions that could cause a problem in one detector to
cause another (sound detector) to chirp.
The answer: "Yes...!"
The suggested solution is to remove all of 'em, reset all of
'em, and then re-install all of 'em.
I'll do that tomorrow.
All the best,
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