Ken Weitzel wrote:
So, anyone buying a new one, with a still usuable but due
for replacement, keep the old one. Put it somewhere safe
on the newest cement available. Keep the kids safe, put it
perhaps on a garage floor.

Leave it alone for a month or two, then take a good look
at it. The case _will_ be covered with salts.

As part of PM I change 1 or 2 batteries a year... the price of owing too
much stuff. I ALWAYS keep the freshest (old) batteries for emergency
use with 12VDC powered radios. So I have done exactly the experiment
you propose.

The old batteries sit directly on my garage floor. I never see any
salts or other deposits on them.