Battery discharging

A previous post reminded me of something I once heard about batteries and leaving them on concrete. Do they discharge because of it?
 
It was reported to be a problem around 1900. I was not there to witness it. Certainly not an issue anymore.
 
They will "self discharge" due to inherent battery chemistry, but that's so on any surface. I heard that (dont set on concrete) yearsssssssssssss ago but don't find it to be any concern nowadays.

John T
 
In past years (ie:, long, long ago), the shells used for batteries would cause condensation on the shell (or case) and there apparently was some amount of moisture movement that was capable through the shell. When this would happen, the condensation could make a very slight contact between cells, thereby discharging them over a few weeks time.

Has been quite a while since I had that explained to me, so probably did not do a very good job of explaining it, but hopefully it's enough to answer the question.

Shells nowdays are made of different materials that cannot allow moisture to permeate through. Now, some folks will say, "Hey, if the cases are waterproof, how can moisture get through?" The best way I can answer that question is to point out a fabric called Gore-Tex that is used in many rainsuits and other clothing. This material will not allow for "water" to flow through, but will allow water vapor to pass to the outside. Gore-Tex is nice as the vapor seems to flow in only one direction. But for the battery shells of yesteryear, moisture vapor could pass both ways through the seemingly impervious materials.

Another example (and probably a better one) is concrete. In the old days, concrete was used to built cisterns, and even though they held water, water vapor could still pass through.
 
When you put a battery in a tractor you put it in a steel box and nothing happens. Steel is a much better conductor than concrete. Explain that one.
 
In 1968 My automechanics prof indicated two factors. One was that the rubber cases were reinforced with material that would allow some conduction to condensed water under the battery on concrete. and that the batteries were really marginal and the owners often used well water in them. This caused self discharge to be dramatic. The battery is dead was a very common issue beyond leaving something on, or an early variety one wire alt. Jim
 
Yes, the old battery discharging on concrete story does have a basis in fact, although the effect is much less pronounced with plastic top batteries compared to old hard rubber tar top batteries with both posts and cell connectors exposed on top.
A little dirt mixed with battery acid on the battery top will allow some current to flow across this acid dirt mix between the two battery posts, add a little condensation moisture to this acid dirt mix and it conducts more current and discharges the battery even faster.
Setting the battery on an insulating material like wood, allows the air to heat the battery to near air temp, so little condensation / sweating effect will happen to wet the battery top.

Now set that battery on 20 tons of cool concrete and it will pull heat out of the battery, keeping it much closer to concrete temp than air temp. This cooler than air battery will form condensation sweating on the dirty acid layer on the battery top causing even faster discharge of the battery, so yes, storing a battery on cool concrete can discharge it faster than having it set on wood or other insulating material off the concrete.
 
I don't buy it.

I'm guessing, "the old battery was taken out, sat on the concrete, 2 years later it's dead", pick it up, the concrete is eaten away under it, must have been the concrete that killed it.

In reality, the battery was already bad, it sat there until completely dead and froze a few times, the case was dripping with acid so it drained down under the case and reacted with the concrete.

The concrete was the victim, not the cause.
 

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