Storing Batteries on Concrete

[Ben]

Interesting article that popped up in my news feed this morning:

https://www.hemmings.com/stories/2021/09/27/why-do-people-including-seasoned-mechanics-still-insist-on-putting-a-block-of-wood-under-a-car-battery

I have always put my batteries on wood if I was storing them on the floor. I don't think discharge has ever been at the forefront of my reasoning, but I'm old enough that I've dealt with refillable lead-acid batteries, so acid spillage/leakage was always one reason, and potential flooding was another. Even a piece of plywood keeps the battery separate from a water spill, not that it's likely a big issue with modern sealed batteries.

Nevertheless, it was ingrained into me at some point in my early years to do it, and I in fact have three AGM batteries sitting on wood in the shop right now, out of habit if not for any logical reason. On the tangent, is Google spying on me again? I just a couple of days ago was reorganizing the shop which is when I moved the batteries onto the wood. Then a couple of days later, this article pops up. I need to put a piece of tape over my phone camera. 

[zxcvbob]

I thought it was due to the alkalinity of the concrete slowly neutralizing the acid in the battery and causing sulphation.  (and also slowly damaging the concrete)  H+ ions are pretty small and might can diffuse through the case.

The article doesn't mention anything about that.  Perhaps because it's my own personal bullshit, but I dunno.

[230RN]

I always figured there was some residual acid floating around a battery and getting on the outside, especially during charging.  I therefore always put a battery on something non-corrosible. Never thought of raising it for flooding, though. Right now, I found a largish pyrex plate from a microwave or someplace and I store a spare battery on that.

H₂SO₄ doesn't have much of a vapor pressure, but it's not zero, either.

My main concern was the H₂ escaping and carrying some droplets from breaking bubbles of hydrogen in the cells to the outside world.  Some of  those droplets must end up on the concrete it's resting on.  Not a big deal with sealed batteries, of course.

Another personal slightly BS habit I have is to never handle a lead-acid battery without a box of baking soda (sodium bicarbonate, NaHCO₃) handy.  And I always wear glasses anyhow disunirregardless of whether I'm working on a battery or not.

Terry, 230RN

[RoadKingLarry]

I was told at a very young age (drill, pounded, smacked into my brain) not set a battery on a concrete floor as it would cause the battery to discharge. Something to do with capacitive coupling.
It's so deeply ingrained in my mind set that I can't get around it.   

[Hawkmoon]

I was told at a very young age (drill, pounded, smacked into my brain) not set a battery on a concrete floor as it would cause the battery to discharge. Something to do with capacitive coupling.
It's so deeply ingrained in my mind set that I can't get around it.

Ditto.

I'm 77 years old. I think my grandfather told me this, so long ago that I have no idea when. (But he died in 1982, and I hadn't seen him since 1980, so it had to have been in the 1960s or 70s). I have never understood -- or cared -- why this is the case, but I have seen it happen enough to know that it's a fact of life. Never store batteries on concrete.

[bedlamite]

Didn't read the article, but you don't need to worry about it since they started making the batteries outer shell out of plastic.

[RocketMan]

I saw the same article, Ben.  I was taught eons ago that it was the temperature of the concrete floor being generally much less than the ambient air, and this gradient can negatively affect battery performance.  The article mentioned this in kind of a sideways fashion.

[K Frame]

I was told at a very young age (drill, pounded, smacked into my brain) not set a battery on a concrete floor as it would cause the battery to discharge. Something to do with capacitive coupling.
It's so deeply ingrained in my mind set that I can't get around it.   

That's what I've always heard, ESPECIALLY if the battery is used and really cruddy on the exterior.

[zahc]

Total BS.

Dirty batteries can self-discharge through the crud on the battery but I don't see how that matters what it's sitting on

Concrete is easily etched by acids. I have a nice big scar on my garage floor from some acid that I spilled. So it makes sense not to set them straight on the ground.

[230RN]

"I was told at a very young age (drill, pounded, smacked into my brain)..."

That could explain a lot. 



"Self-discharge through the crud on the battery."

Yes, from the inevitable electrolyte which escapes and is deposited on the battery case.  But batteries do self-discharge internally all by themselves.  (Largely because of the inevitable impurities in the mix and the electrodes which allow the occasional transport of electrons / ions from one side of the battery to the other internally, constituting a sloooooow discharge.  I note that some cells ("batteries") nowadays are advertised has having a 10-year shelf life, which is probably partially due to the extreme purities we are now routinely capable of in their construction.)

"Capacitive coupling..."

Explain that one to me, please?

[Hawkmoon]

Yes, from the inevitable electrolyte which escapes and is deposited on the battery case.  But batteries do self-discharge internally all by themselves.  (Largely because of the inevitable impurities in the mix and the electrodes which allow the occasional transport of electrons / ions from one side of the battery to the other internally, constituting a sloooooow discharge. I note that some cells ("batteries") nowadays are advertised has having a 10-year shelf life, which is probably partially due to the extreme purities we are now routinely capable of in their construction.)

Yeah -- alkaline flashlight batteries.

Buy a new lead-acid automotive battery, charge it up, and plunk it on a concrete slab. See how long the charge lasts.

[230RN]

Just for grins I followed the internal discharge of some old Ni-Cads in an ancient DeWalt drill immediately after a full charge.  I had had them replaced on August 2012 by the local Interstate Battery store on 12650 W 64th Ave, Arvada, CO 80004 (good guys, my 100% + rating.)

Measurements were taken 21 Aug 2019.  By then, I'm sure the battery was run to "zero" volts (would not turn the drill motor with no load) and a few of the cells must have got reverse-charged several times.

Anyhow, just for grins and FWIW:

----------------------------------------

DE WALT BATTERY DECAY
MARKED BATTERY VOLTAGE IS 9.6v

AVG IS ABOUT 0.1V PER DAY FOR
FIRST TEN DAYS

VOLTS   TIME   DATE
11.0   6:40PM   10AUG (2019)
10.69   7:45PM
10.63   8:45PM
10.53   10:45PM
-----------
10.47   1:00AM   11AUG
10.39   5:00AM
10.34   8:45AM
10.30   1:45PM
10.28   5:30PM
10.27   7:35PM
10.24   11:55PM
--------------
10.21   1:05AM   12AUG
10.20   2:30PM
10.19   9:40PM
--------------
10.18   12:15AM   13AUG
10.15   7:45AM
10.15   11:30AM
10.14   7:25PM
10.10   4:45PM   14AUG
10.09   12:22PM   15AUG
10.06   4:37PM
10.02   10:25PM   
10.01   6:35
9.97   1`:10PM
9.91   3:10PM   18AUG
9.75   2:30AM   21AUG
9.69   3:20PM   21 AUG WED~

-------------------------------------

What brought this up now is coincidentally, I was recently thinking of getting those Ni-Cad cells replaced again and came across this data.

Enjoy.

Or not.

Whatever.

Terry, 230RN

ETA:  Current Present voltage on the battery is 6.56.  Probably two-three months since I last charged it.