Re: batteries and high heat

[P3D James R. Motley <jmotley3d@xxxxxxxxxxxxx>]

Thanks to Bob Wier for the informative posting which he obtained from
the GPS usenet group.  While this study pertained to a specific problem,
it brings to mind the effect of temperature on rate of chemical
reactions in general. 

As I recollect, the general rule is that chemical reactions double for
every 10 degree Centigrade increase (18F increase). This means that the
"self discharge rate", which determines the "shelf life" of a battery
can be affected drastically by heat.  Regarding the sticking problem,
Duracell indicated that +70C should give no ill effects "other than
capacity degradation".  Considering +20C (68F) as a base, the "self
discharge rate" at +70C (158F) would be 32 times greater and 64 times
greater at +80C (176F).      

Keeping this general rule in mind, it becomes obvious that heat can
seriously degrade  batteries and film.  Not only  should cameras not be
left in a hot car, but also don't buy batteries or film that have sat in
the sun week after week at a flea market.

Trivia question: Which is colder, -40C or -40F???  (Or should this be on
Tech-3D?)

Regards....Jim Motley


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