OT: Smoke Dectector puzzle...

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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 old).
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 mostly.
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.
Allen

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Allen Roy wrote:

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.
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IOW the test button does not fully discharge the circuit and it chirps to warn you that the power is off, right?

No need to. I make blackened catfish once in a while.
--
FF


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wrote:

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.
Allen
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The detector in my shop went off a couple of weeks ago. When I opened the case, a spider ran out.
--
"Keep your ass behind you."

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[snip]...

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 supplier.
GWK
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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.
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On 5 Mar 2007 09:35:00 -0800, snipped-for-privacy@heapg.com wrote:

Hi again,
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?"
Thanks,
--
Kenneth

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Kenneth wrote:

Yes, the test Beep circuit does not have enough voltage to fire but the chirp circuit can still work for a while on the residual charge.
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On 6 Mar 2007 09:58:45 -0800, snipped-for-privacy@heapg.com wrote:

Interesting...
Thanks,
--
Kenneth

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On Tue, 06 Mar 2007 17:57:25 -0500, Kenneth

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,
--
Kenneth

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