On 16/03/2018 16:16, alan_m wrote:
On 16/03/2018 14:10, Clive Page wrote:
While lying awake last night I heard short beeps at long intervals, almost certainly a smoke alarm trying to tell me its battery was low, but I couldn't be bothered to get up to find which one (of two) it was. In the morning, by some variant of Murphy's Law, the beeping had stopped but both worked perfectly well when I pressed their test buttons.

It's temperature. During the night the battery gets colder and the terminal voltage drops.

I thought it might be. It's surprising that a degree or two would make that much difference though.


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Clive Page