there is science behind it, but i dont much belive it.
IMO some of it is a old wives tale, Because:
When you took old batteries out of a car, they put them on the cement, well :-)
When you did not attend to a battery it was on the cement, a discharged lead acid goes bad over time.
LA batteries dont last long anyways, by the time you came back to that battery you left in the garage, + not keeping it charged, it was ruined.
jarring a battery knocks the stuff off the plates of the old ones, which ruins it faster, every rechargable battery i have used doesn't like to be dropped either.
so
if you keep it charged, gently place it,keep the water in it, that would only leave this science that some chemical reaction from the cement messes with em, and i think its the least of the problems.
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4. Do Not keep automotive batteries on a cement floor as this can cause them to drain more quickly (some people say this is an urban myth and others say it's not the cement/concrete itself but the temeperature difference between the concrete and the air in the room)
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ahh temperature diferentials??
to be safe what could possibly be the problem with putting them on a board?