for what it's worth, my understanding was that the dischage when placed on
concrete (or metal) related to the early automotive batteries with hard
rubber cases (not bakelite), because the cases had carbon black as the
darkening agent and were thus slightly conductive. I understand that with
modern poly-plastic cases this is no longer the case.


"Don Foreman" wrote in message
...
On Sun, 11 Sep 2005 12:45:25 -0500, "R. O'Brian"
wrote:

There is a little known phenomena called electrolyte stratification where
a
cold concrete floor can increase the self discharge rate of a lead acid
battery. The bottom layer of electrolyte gets cooled by conduction from
the
floor while the upper layer stays basically at room temp. Since there is
no
natural circulation to mix the layers, the situation is static and the
increased leakage current flow will eventually discharge the battery.
Diesel-electric submarines had bubbler tubes in their batteries to agitate
the electrolyte . The problem was potentially serious because the
batteries
were exposed to very wide temp. ranges in submarine duty.
See http://www.uuhome.de/william.darden/...4.htm#concrete

This pertains to large batteries in an environment where the floor
(or submarine hull) is much colder than the surrounding air. I
don't think it's an issue in a garage -- but it's easy enough to set
the battery on a block of wood.

It wouldn't be an issue if a maintenance charger is present.