At 12:14 PM 5/27/2004 -0400, Dipperstein, Michael wrote:

>Fred,
>
>The voltage you measure from a 9 Volt alkaline battery near the end of its life
>depends upon the load placed on the battery at the time you are measuring it.
>You can take an alkaline battery that is near the end of it's life and allow it
>to sit on a shelf for a while and measure it's voltage.  The voltage will read
>pretty high.  Draw some current from the battery and the voltage will drop
>rapidly.  The more you draw, the sharper the drop.  Let the battery rest again
>and the voltage will pop back up.

Therein lies the root of the problem.
The voltage doesn't really fall (until much later) but the impedance goes up and up.
Measuring the battery impedance is what you really want to do.

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