On 03/10/2020 11:56, NY wrote:
My wife has always believed that if you touch both (and maybe just one)
terminal of a flat disc "button" battery (eg CR2032, CR1620 as used in a
watch, key fob, PC BIOS), you will cause the battery to discharge, so
you must take care when fitting a new battery not to "short the
terminals with your fingers".

Bridging the insulation between the positive and negative terminals with
a sweaty fingerprint will shorten the battery life somewhat. But it
would have to be a very low capacity battery for holding onto the
terminals for a few seconds. Very few people are lower than 50k skin
resistance and some are as high as 10M.

Biggest danger from them is children swallowing them which can cause
very serous internal electrolytic burns.

I can imagine that sweat on the metal terminals *may* cause a bit of
oxidation over a long period of time, but I can't see how a body
resistance of many kilohms will cause the battery to go flat.

Is there any truth in what she's always believed and what she advises me
to do?

There is truth in the don't put a fingerprint across the insulation that
separates the two terminals. Much like don't put fingerprints onto
quartz halogen bulbs - the sodium chloride and skin oils cause trouble.

--
Regards,
Martin Brown