Smoke alarms
Posted on July 19, 2008 at 1:21pm | 3 comments
A smoke alarm woke us up the other night. It wasn’t warning us about a fire ripping through the house, but rather its battery was running down.
That was the second time in a fortnight (separate alarms).
Why do smoke alarm battery warnings only start beeping at 3am? Why can’t they make that irritating sound in the afternoon?
Tags: life
I normally change my batteries with daylight savings. However, twice I’ve forgotten … and twice the battery has tripped the warning beep in the wee hours.
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Ah, the dreaded early morning false alarm!
Smoke detectors go off between 2am-6am because the ambient temperature drops considerably then. This causes the battery voltage to drop below the smoke detector’s low voltage warning level and bingo, off she goes!!!
It is worse in winter of course. Houses are nice and cosy when the heater is on but when everyone is off to bed and the heater has been turned off, the temperature drop is exacerbated. As with all batteries, especially car batteries, cold winter weather usually sorts them out. Hence, lots of battery warnings will occur during winter.
However, there is an alternate but less plausible reason for alarms going off in the early hours. The 3am-4am time slot is noted for the increased activity of spirits that may be haunting the premises. Believe it or not, we have them, two actually. One is a young 12 year old boy and the other is an elderly man about 60-70 years old. The four of us in the family had seen these “ghosts” at different times but weren’t game enough to raise the issue until the subject was covered on a TV documentary. Without any form of collaboration, each of us described the two individuals exactly the same way, including age, sex and even the clothes they were wearing. Spooky hey? The young one takes great delight in hiding my sunglasses for days but always returns them to my storage spot within a week. Perhaps ghosts like to trip off alarms too? It means that they have to be at least 6 feet tall to reach the test button!
Fantastic theories Glenn! One sounds scientifically plausible and the other is entertaining