P3D Re: Ni-Cad batteries

[jacob@xxxxxxxxxxxxxx (Gabriel Jacob)]

Bill Stickley
>I would disagree that higher currents supplied by ni-cads is the 
>reason.

Sorry Bill, but this is not true. The major reason ni-cads are not
recommended IS because of the higher current. 

>It is much more likely that ni-cads of a given size are 
>rated as less voltage than comparable alkaline batteries. For 
>example size AAA, AA, C and D alkaline cells are rated at 1.5 volts.
>The equivelent ni-cads are generally rated at 1.2 volts.

The differing voltages is immaterial in these discussions. Most P&S
cameras, flashes, etc. are made to work under a range of voltages
due to the voltage decrease with use of regular batteries. Thus they
are very tolerant of voltage. In anycase the manufacturers are not
saying don't use ni-cads because it won't work with your camera but
because it might ruin your camera and never work. Sure they need a
minimum voltage to operate but ni-cads are not a problem in this regard.

>Most alkaline cells are considered completley discharged at 0.8 volts.
>With this in mind you can see that fully charged ni-cads act like
>they are halfway discharged alkalines.

Your making some erroneous conclusions here. You can't equate the
voltage of the DIFFERENT types of batteries with it's current capacity.
Your comparing apples and oranges by comparing a fully charged ni-cad
to a halfway discharged alkaline. If were comparing the the voltage of
an alkaline at 1.2 vs. a 1.5 you can make some kind of generalization
but not with a ni-cad. An easy example (from many) to understand this
is a 1.5V D size alkaline battery vs. a 1.5V AAA size alkaline battery.
Same voltage, same internal chemistry but very different current
capabilities! 

So in closing, manufacturers don't recommend ni-cads (in certain cases)
because they might fry your equipment and not because it might not
operate your equipment. If that was the case (not operate) they wouldn't
bother with the warning.

Now the real question is...
Why dont' 3D cameras use 3 D size batteries!?! 

Gabriel


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