> > I have a question.  At what voltage do you read from the 9v battery do
you
> > determine that it should be changed?  I am building a device using some
9v
> > alkaline batteries and I am putting a low battery indicator circuit to
> > light

> Several battery manufacturers specify the EOL (End Of Life) point of
> their batteries in their documentation. Eveready ("Energizer Bunny"
> folks have published several books on the subject; Duracell does too.

That's the best answer - but as a rule of thumb 1v per cell = 6v for a 9v
battery is a reasonable end point. An alkaline cell is still going at 0.9v
but the end cometh soon. Depends on how much reserve you want. Temperature
extremes will also affect this.



        RM

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