On Sun, 23 Mar 2008 20:50:56 -0400, Joseph Gwinn
wrote:

In article ,
Ned Simmons wrote:



Batteries are too small to support much of a thermocline. It takes at
least a lake to get anything that will last more than an hour or two.


I didn't see any mention of a thermocline. What's been proposed is a
temperature gradient in a battery cell that's packed with enough stuff
to inhibit convection when set on a relatively good conductor that's
at a different temperature than the ambient air.

Lew Hartwick mentioned the thermocline.

I don't see that in Lew's posts, perhaps I missed one.


But anyway, what's the thermal conductivity of the metal battery plates,
and of the electrolyte? It has to be 1000 times greater than air, and
unless the battery is *huge*, thermal equilibrium will soon be achieved.


The heat capacity of a concrete slab and the earth below it is huge
compared to the battery, and it may take days to reach equilibrium
with the air. In the meantime, if the weather is trending warmer, the
bottom of the battery is cooled below ambient by the slab. I have no
idea whether the effect is actually large enough to discharge an
otherwise healthy battery, but I don't think the possibility can be
dismissed without either an experiment or some very messy
calculations.

In any case, I find the notion more plausible than *'s assertion that,
"Electrons WOULD leak through the porous case to ground - eventually
discharging the battery." g

--
Ned Simmons