On Tue, 16 Aug 2005 03:19:55 GMT, Ken Weitzel
wrote:



wrote:
1. Urban myth

2. Alkaline cement/battery acid

3. Dust dirt and moisture

4. Basement floor

CJT said he never had a problem, but didn't mention anything about
time. How long ? Nobody ever said it was dead in minutes, or even
hours.

A buddy and I have been discussing this, after reading the responses
and I can no longer summarily dismiss the effect, if the "urban legend"
is indeed true. At this stage I must admit that there is a possibility.

2. A reaction between whatever solubles are in or on the cement, along
with the highly acidic content of the battery housing, which has some
porosity, is an interesting possibility.

All of this might be enhanced in more humid climates. Even on cement,
even if it doesn't rain, if left long enough metals will corrode or
rust on the bottom.

3.Basement floor : While copper is an excellent conductor, cement is
not. That is not to say it is a good insulator. Your legs act as wires,
not very good wires, but functional enough to kill. If you are barefoot
on cement, it's not making all that good of a wire either, but look at
your footprint and you see the cross-sectional of this wire. A bit
bigger than the wires in your basic 12-2 Romex you think ? A copper
conductor of that size could carry thousands of amps. It needs alot
less to burn you, or to discharge your puny battery over time.The
linear resistance of a piece of wire is inversely proportional to it's
cross sectional area. So what do we have here, how many ohms ?

Actually I would be at a disadvantage here with my 13 wide sized feet.

When I want to know if something is true I need to prove it to myself.
Thanks all so far. I play Devil's advocate against my own initial point
of view for that reason. All these factors are evidence that this myth
might be true, but initially came from personal obsevations. Cause was
attributed to effect, but the matter was not looked into further.

Hi...

First - the story never ever called for hours, or minutes.
Being perhaps the "old guy", I believe it came from those
"olden" days when cars were put aside for the winter.
(at least here in Winnipeg (Winterpeg) Canada, where we
get more than our share of -40 degree days.

Folks would drain fluids, remove tires and put the car up
on blocks, and bring the battery inside to store in the
basement. So we were talking 4 or 6 month periods.

Second - in support of my position, I invite an experiment
from any who are willing and in a position to do it.

Those of us who change our own batteries pay a 5 dollar
deposit when we buy a new one, refundable whenever we
return the dud. I suspect not many would suffer much were
they to do without that 5 bucks for a month or two.

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.

I fail kindergarten level chemistry, but what are those
salts? Where did they come from, and what effect does their
loss have on the battery?

Let us know; then take the battery back for your 5 bucks

Take care.

Ken

I've worked with rechargeable batteries for many a moon and in my past
experience have seen batteries that weren't properly isolated from
ground contact drain much faster than those that were placed on rubber
mats or insulated storage boxes.
It includes nicads as well as traditional lead-acid.(including gel or
dry cell.)
When I worked in service as a photographer rechargeable modules were
the lifeblood of virtually every type of photographic system we
employed. From regular hand held cameras and strobe equipment the
belly cameras on recon aircraft.
We had a entire section of every ground base lab devoted to service
and charging of all the various types of batteries we used.
The one cardinal rule we had for batteries was never to leave them
sitting on bare ground or concrete.
Many of the larger modules even had their own storage cases, usually
steel with a rubber coating inside.
I distinctly recall on lab I transferred to having problems with the
battey modules for their strobes suffering from short charge life and
early death.
They'd be charged every evening by the nigh****ch and stored in a
metal storage locker for use by morning crews the following day.
The locker sat on a bare concrete floor and the plastic encased
modules were simply stacked onto the painted shelves of the locker.
None of the battery contacts came in contact with any conductive
suface but if left on the bare shelves of the locker would would
completely discharge in about 3 days or less.
I ran a test by placing a fully charged battery in a heavy plastic bag
and left it in the locker for a week, with another charged module
sitting right next to it on the shelf.
The bagged battery retained nearly all it's charge, the bare one was
dead.
After that we used a heavy plastic case with rubber mat to store the
batteries and the problem was resolved.

I've been told by those more knowledgeable than I in matters of
storage devices that there are instances where batteries can discharge
due to grounding.
I'm told it has something to do with relative humidity, also that sea
air also promotes rapid discharge as well.(salt in the air?)
My old man was an electrician who served his time on diesel
boats.(submarines) and he was a big believer in isolating batteries
from ground as well.