On Fri, 18 Jun 2010 07:23:17 -0700 (PDT), "Man at B&Q"
wrote:

On Jun 18, 2:58*pm, Mark
wrote:
On Fri, 18 Jun 2010 13:41:29 +0100, "Brian Gregory [UK]"



wrote:
"Mark" wrote in message
.. .
On Fri, 18 Jun 2010 03:17:27 -0700 (PDT), "Man at B&Q"
wrote:

On Jun 17, 6:46 pm, Bodincus wrote:

And - by the way - since when is the voltage of a battery an indication
of the residual power in it?

http://www.farnell.com/datasheets/97133.pdf

NiCD and NiMH have a pretty flat discharge curve so the voltage
remains fairly stable until they are about 90% discharged.

Therefore voltage is a fairly good, if crude, way of estimating the
charge left it these types. *The same is not true for alkalis.

The voltage change is so small with Ni-Cad and Ni-MH that differences due to
ambient temperature changes and between individual cells (due to impurities
maybe, I don't know) can be nearly as much and can make any estimate of
charge left unreliable.

Maybe I did not phrase my point well. *What I meant was an absolute
voltage threshold is a useful way of detecting when a NiCD or NiMH is
nearly fully discharged. *It's the way my digital camera uses. *This
method is not good when Alkali batteries are used since the voltage
gradually drops as it discharges and the camera will report a dead
battery when there is plenty of life left in it.

But only because the wrong threshold is being used for the type of
battery.

I doubt they have the ability to detect the type of battery used.
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