OT: Smoke Dectector puzzle...

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Howdy,
We have a total of 6 smoke detectors in our home. They are of the sort that has AC power to all of 'em, and each has a 9 volt battery "backup." All six are on the same AC circuit.
When one of them starts to "chirp" (indicating low battery), we replace the batteries in all of them.
This is the drill:
I remove AC at the breaker. I remove batteries from all six detectors. I press the "test" button on each (discharging the internal capacitor, and generating a few feeble beeps.) Then, I put new batteries in each. And finally, I turn on AC at the breaker.
Here's the puzzle:
Right now, I have the AC power off, all six have had their batteries removed, and all have had their test button pushed but...
Every few minutes, and apparently randomly, they are chirping individually.
I can't figure out where they are getting the energy to generate the chirp sound.
Do these things photosynthesize?
In any case, I would welcome any thoughts on how this might happen.
Sincere thanks,
--
Kenneth

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snipped-for-privacy@soleSPAMLESSassociates.com says...

You have birds nesting in the attic?
-P.
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You wired your house like mine where the smoke detectors are on a dedicated circuit? The smoke detectors have an alarm wire so if one alarms they all alarm? I change the batteries one at a time. Good batteries last years longer than cheap batteries. I will ignore the you must change the batteries every year crowd. I change my oil in the car every 10,000 miles but that is the oil change interval. No ideas on your issue though. My guess or question would be if you remove each and every detector at the same time, they all sit at the kitchen table as you replace the batteries?
On Sun, 04 Mar 2007 17:31:33 -0500, Kenneth

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Ok, here is a better question for me. At what battery voltage should you replace the batteries?
On Sun, 04 Mar 2007 23:03:17 GMT, Jim Behning

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I change my oil in the

You might want to reconsider that change interval if you drive daily in the city. I worked in the automotive business and retired from it 10 years ago. Manufactures recommended oil change intervals are almost always under optimal driving conditions and any driving in the city is not considered optimal. Additionally I have always gone for the every 3,000 mile interval. A few years ago I made the mistake of buying 2 two new VW's 2 years apart. The service advisors would kinda laugh when I came in for the oil change at 3,000 miles and would point out to me that 10,000 miles was indicated. Just before getting rid of the last VW I received a letter from VW advising all owners to change the oil every 3,000 miles despite what the owners manual indicated and highly advised using a synthetic oil. Guess who got to give the service advisor the funny look the next time I took the car in for the oil change.
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I agree with you. I'm an ex mechanic. I have seen the crud in oil from letting it go to long. No crud is good crud. It wears on your engine. Oil is cheap, engines aren't.

the
Just
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My Toyota has 274,000 miles on it. I change the oil when I think about it. Sometimes 5,000 miles sometimes 15,000 miles. The 15,000 or greater intervals were mistakes. Kind of forget when the oil level does not drop much between changes. Actually I think I did 25,000 miles one oil change intentionally to see what an oil anaysis looked like. I had the head off that truck not that long ago. No nasty junk on the head. Still crosshatch marks in the cylinders. I have had VWs with negligble wear in the cylinders with same erratic oil changes. Heads are pretty clean. I do not drive severe duty driving. Well at least now that I do not have to tow a horse trailer as my wife is not showing horses. I really don't believe that changing the oil every month is going to benefit me. My 4 year old VW has 148,000 miles on it but I think I have used about 5,000 gallons of fuel. Yes fuel consumed has notthing to do with the discussion. I will probably keep that car for more like 500,000 miles if I keep with the same crazy amount of driving.
When I was a kid I recall sludge on heads all the time on cars I might touch in Cleveland Ohio. I was a kid so they were not my cars. Subzero weather and less than 10 mile trips are harder on cars and oil than my almost always above zero Atlanta weather and my 40+ mile one way drives. I have used synthetic oil since about 1985 without any signs of oil problems. Extended oil changes with regular oil in severe duty is crazy. I also do not drive 100 mph everywhere which would get it back to severe duty. On the other hand I do not keep cars long. I seem to get rid of them when they have 300,000 miles on them. Toyota should be around another 5 years as I do not drive it that much now. I have had it just 20 years now.
My 67 Beetle went through a few engines and I changed the oil as per the manual. Every 3,000 miles. But that was before I used synthetic engine oil. But most aircooled engines were due for a rebuild every 100,000 miles. At minimum new exhaust valves and a set of guides.
Where I live and the way I drive you could never convince me that 3,000 mile oil changes benefits anyone but the oil companies. If I lived in a cold climate I might have a different idea. Also if oil analysis told me I was crazy then I would change my habits.

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It sounds like you do mostly highway driving and don't live very far South where hot days, 98 degrees and up, are normal. The synthetic oil is the key for your good luck and probably because you don't go extended periods of time between changes. Contamination build up is what wears the engines whether the oil is worn out or not. If you are changing the oil often, time wise, regardless of miles, that is also key in keeping the engine in good shape.
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On Mon, 05 Mar 2007 13:22:38 GMT, "Leon"

Well it is sort of hot in Atlanta. I buy my oil filters 6-10 at a time. Enough for two years of oil changes. I am probably using the wrong syntehtic oil but it is too much of a pain to buy 4 gallons at a time at the oil wholesaler. Stupid whine there but semi conflicting labels on the oil. Now I am abusing my tractor engine. I really should not do that as it does not get its annual oil change. Next time it is warm I need to change it. I guess you guys convinced me to at least treat the tractor better. How can I move Unisaws around if my tractor dies? I need to treat the tractor better.
Back to your regularly schedule off topic smoke detector discussion.
Did anyone have an answer to what is the threshold battery voltage where you should change a smoke detector battery?
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Jim Behning wrote:

It's a difficult question to answer. Typical alkaline batteries maintain a fairly constant voltage until they fail. You can see various discharge charts at:
http://www.powerstream.com/9V-Alkaline-tests.htm
Batteries are inexpensive. Change them at the recommended interval. Your life could depend on it.
--
Jack Novak
Buffalo, NY - USA
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dodging blocks of wood thrown. That explains why I have had batteries fail at less than a year while others have lasted for years. There appears to be a huge difference in performance.
Thnaks for the link. I need to stop by the emergency battery store tomorrow to see what they have.

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So the service manager wrote corporate and said "Hey, we got a guy that comes in every 3000 miles to change his oil even though we told him 10,000 was good, think we could convince the rest of the customers to burn money like this?" They sent him a bonus check for the great idea. You come in, give him the funny look, he goes in the back and high fives all the other guys...;+}
-jtpr
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Is the smoke blocking the view? ;~)
I have had that problem, it fixed itself. This started one time in the middle of the night with no reason. By morning the chirping had stopped.
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"Kenneth" wrote in message

Many of these battery+hard wired smoke detectors seem to chirp, with or without a battery, if there is suddenly a loose power connection in that unit, or in the circuit.
So, in addition to the obvious things, I would also check for a loose connection, maybe to that unit, or somewhere in the hardwired circuit, especially if you just powered that circuit off and on.
Amazing how often a "bad connection" shows up in new construction that has just been powered on and off a few times in the electrical trim out/testing stage. A circuit that worked an hour ago, may not an hour from now due to a connection somewhere in the run that was somehow "loosened" during one of these power cycles.
AAMOF, I've got one in chirping in a new house as we speak ... noticed it yesterday, and, since it is unoccupied, I will deal with it tomorrow. ;)
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On Sun, 4 Mar 2007 17:45:58 -0600, "Swingman"

Hello again,
The device was connected to a circuit with the breaker tripped. There was no battery installed.
The reset button had been pressed.
How did it get the energy to chirp?
Thanks,
--
Kenneth

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"Kenneth" wrote in message

"With the breaker tripped" is basically the same as if there was a loose/no connection ... IOW, no power to the unit from either the battery, or the house electrical service.

Stored in an onboard capacitor, from when it was previously powered, for just the eventuality that you describe.

You're welcome.
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"Swingman" wrote

After careful consideration, I have decided that the manufacturer includes this feature to annoy us. This is the basis for many designs in consumer products.
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"Lee Michaels" wrote in message

There are many like this ... I really do want to commit murder on the bastids who manufacture and sell "un-rippable by human hands without a sharp object" PLASTIC wrapping.
Then there's the unspeakable things I would _cheerfully_ do to the purveyors of "ED" medications who advertise during "family time" TV hours, and those that accept said commercials.
Don't get me started ...
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On Mon, 5 Mar 2007 14:03:02 -0600, "Swingman"

Hi again,
It is my understanding that pressing the reset button discharges the capacitor. At least, that is what I was told by the tech support person working for the manufacturer.
Thanks again,
--
Kenneth

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"Kenneth" wrote in message
How did it get the energy to chirp?
This is a woodworking forum ... direct your question to the maker of the particular unit to get something besides a SWAG.
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