On Sun, 6 Oct 2002, Attila Muhi wrote:

*>>*>So, if it doesn=B4t work, will NiMH:s or NiCd:s behave better ? I do=
n't
*>>*>need to draw a lot of current, max 150 mA peak.
*>
*>>Imho try to use a Lithium battery. Lithium likes it cold afaik.
*>
*>What you say makes sense, I guess. But, is NiMH or NiCd still a better
*>alternative than jelly ?

Not pricewise. NiCd and NiMH also do not like extreme cold, but less then
lead. You will find that storage temperature for solid electrolyte
batteries (like Lithium) can be -55C. For anything with liquid in it the
minimum storage temperature is essentially above the freeze point of the
electrolyte.

*>Peak current in my app will be around 150mA, but only for about 2-3
*>percent of the time. Normal current will be around 1 mA. Guess that
*>won't heat the acc enough. The capacity needed is around 10Ah.
*>
*>The discharge curves are also of interest. What happens with lithium
*>cells, do they drop slowly like dry cells, or do they keep up the
*>voltage during the discharge cycle ?

Please do get some data sheets by searching the net. It's all there.
Lithium has a more pronounced voltage slope then all the other batteries.
F.ex. a two cell battery would have 8.4V when charged and a little above
6V when discharged. The exact voltage depends on cell chemistry and
temperature (and you need to account for both or the cells will be
destroyed).

Peter

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