Re: [photo-3d] Nimh / NiCad / Alkaline

["Dr. George A. Themelis" <drt-3d@xxxxxxx>]

>Plus: cells keep voltage up near rated (1.5V) for most of discharge period.
>Alkalines: flashlights and Red-Button VIEWERS, where you have moderate
>          power drain, but you want constant voltage.  

It is not true that Alkaline cells maintain a constant
voltage for most of the discharge period.  The fact is
that the voltage drops continuously with use.  If you
measure the voltage of a pair of alkaline batteries
in a red button viewer that has been used for a while,
you might find the total voltage to be 2.0V instead
of 2.8 or 3.0V.

I provide the following recommendation:

- Use alkaline batteries if you don't use the viewer
very often (because of the charging/discharging
inconveniences)

- Use rechargeable batteries if you use the viewer
often.  Have a second pair on hand always charged.

Personally, I use rechargeable batteries because they
are light weight and offer relatively constant voltage,
in my Realist red button viewer (most used viewer) and
alkaline batteries in my less used VM Model D, flashlights,
etc.

>Of course batteries can be made in different "energy densities". For
>example, Radio Shack sells 2 'D' size NiCD's. 1400 mAH for US 3.50 or
>4500 mAh for US 8.00. That's about 3 times more current capacity for
>about twice the price so it pays to shop around. 

My personal recommendation is to use the batteries
with the lower charge capacity (1400 mAH in this case)
because they are lighter in weight.  One of the
advantages of NiCd's over Alkaline batteries
is the difference in weight.  This makes the viewer
easier to hold, less prone to dropping (we all know
what happens when you drop your red button) and the
damage will be reduced if the viewer is dropped.
Using the high capacity rechargeable batteries 
eliminates this weight savings and keeps all the
disadvantages of rechargeable batteries.

Not every one agrees with me... but this is my
recommendation.

George Themelis