Do batteries discharge on the floor?

The myth goes: ‘If you store car batteries on a concrete floor, they will short to ground and discharge slowly over time.’
I always argued with the old saying, but until now I never had proof.
This video includes a two-week test to see if the myth is true or gets busted.
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[@rdththth]

The self-discharge effect is not due to the concrete itself, but how the concrete delays temperature changes at the base of the battery. All lead-acid batteries will self-discharge, even with no load applied. The rate of self-discharge can be influenced by variations in temperature. Batteries are most efficient at around the same temperatures at which humans feel comfortable. The voltage of a battery varies slightly with temperature. Generally, as the temperature drops, so does the voltage. Let’s assume the concrete was poured directly onto earth, is shaded from direct sunlight, and the earth influences the temperature of the concrete. The temperature of the air will change faster, and to greater extremes, than the temperature of the concrete. The temperature of the concrete will be cooler than the ambient air during hot weather, and warmer than the ambient air during cold weather. If the top and bottom of a battery are at different temperatures, then the top and bottom of the plates want to be at slightly different voltages. This will cause a small current to flow within the battery, resulting in a slow self-discharge. If a battery sits directly on concrete, and is exposed to large variations in ambient air temperature, then the top of the battery will change temperature more than the bottom, resulting in a slight internal current that will slowly discharge the battery. Placing a thermal insulator under the battery, such as a block of wood, will reduce the self-discharge rate of a battery sitting on a concrete floor.

[@ToolDemos]

That was very well explained. Thank you.

[@GeorgeJFW]

Great video this is a piece of advice that was accurate but it no longer relevant. very old lead-acid batteries had glass cells all encased in a wooden box. This means that if they were left on concrete or cement floors, the moisture from the floor could cause the wooden box to wrap, allowing the glass cells to shift and break. I have been told it can discharge modern batteries if the cement s very cold. It’s generates a temperature difference from the top of the battery to the bottom causing internal convention currents that can increase the speed of the chemical reaction. That being said I don’t buy it. 🍻

[@ToolDemos]

Okay, so there is a basis for the myth. That’s cool, thank you. The convection theory sounds ‘sciency’ but I’m with you on that one.

[@PowerStrokeJude]

I usually try to store batteries wherever there is a spot, floor shelf, bench wherever, but I've always wondered if a battery would discharge on a shop floor. Now I know not to worry about that any more, lol. Great video dude!!!

[@ToolDemos]

Thanks Jude. As Will said, don’t put ‘em where you’ll trip over it. Haha

[@NutsandBoltswithTone]

Great video, when I first started an old time told me this and then after a few years in the industry I have figured out is not true. Thank you for the test Steve.

[@ToolDemos]

Thanks Tony. Isn’t it funny how these ideas spread?

[@SolderBrothers]

It is my understanding that this “myth” originates from when early batteries, before plastics, the battery case was made from leather. The best they had at the time. The leather case of the battery, on concrete, would leach the acid through the leather, into the concrete, and created a conductive path that would discharge the battery. Thus the myth to not store them on the floor.

[@juliuspekar7620]

Put the one that shows a reading thru the plastic casing on the floor. To bust a myth you have to try all circumstances.

[@TechMay]

That’s a nice looking shop ! I have never heard of someone saying putting batteries discharges the battery. This is an awesome video, one that shows completely how you did everything in a very clear picture!! Love love love this !!!!

[@ToolDemos]

Thanks May. I know this is your field of expertise and I appreciate your feedback.

[@rosascreativeworks5403]

Nope. Never heard that one.... Unless maybe it was a 9 volt and set directly on it's contacts...

[@ToolDemos]

That would be bad!

[@kowboykennyware]

More of an issue back when they were carbon case

[@prakashm1468]

After I saw your video, I decided to try this test on my newly tiled floor in our house...but didn't take into account the temp drop due to winter. My conclusion is: bare concrete or floor does NOT alter or directly affect the charge at all. But temperature does seem to have an effect on it on bare concrete.

[@ToolDemos]

Makes sense.

[@chada472]

The case can allow electrons to pass through the case and cause it to discharge. If this happens it means the battery needs to be replaced. On cars with metal battery trays this can cause the battery to drain slowly.

[@myfalconry76]

Set them directly on the ground for two weeks not concrete

[@Itsdazeni]

Great video

[@ToolDemos]

Thanks Davion. I appreciate you.

[@ddpeak1]

Brilliant, we’ve had this bollocks at our museum, when they are fitted to the bus etc. they are on steel.

[@ToolDemos]

I hope this myth goes away.

[@felicianvictor8223]

Volts may not drop that much, how about the current?

[@ToolDemos]

Good point. Next time I do this, I’ll use a battery tester to get the CCA.

[@mikevanessen8687]

Do you think the old batteries from the old day1920-1970 would go dead on the concrete? The new and old batteries are about the same construction so I’m thinking not..

[@ToolDemos]

The comment from Junk From Work has some good info on that. He said they used to have glass cells that could break.

[@jasongenn39]

Ha ha i’m from Australia and that wives tale is spread here also. But thank you for putting it to rest

[@ToolDemos]

I hope so, thanks.

[@JOMaMa..]

The battery that had high resistance to the case is from a dirty battery, if you look close you’ll probably see a vent trace across the poles

[@ToolDemos]

Thanks Jo, that makes sense. I’ll check that in the morning.

[@lowkey87685]

I have 99 problems and battery discharge aint one. thanks for taking the time.

[@ToolDemos]

Haha! Awesome, thanks.

[@kennyweaver9796]

Very underrated video! I work at a battery store and I will send this link to everyone who’s questions it!

[@ToolDemos]

Let’s kill this myth.

[@larrysurtees5504]

Cool, glad I watched.

[@JamesDParryjr]

Thank you very much

[@ToolDemos]

Anytime

[@anthonygm85]

I toss my battery's on a sheet of ply board still

[@ToolDemos]

That’s a pretty common thing to do.

[@brentvonaschen7064]

Might be a bad battery is a bad battery

[@ToolDemos]

That is very possible Brent. Could be where the myth originated.

[@themadbrooker4797]

Good experiment!

[@ToolDemos]

Thanks Brooke. I was 99% sure, but I had to know. You know?

[@mrmidnight32]

I might not be able to explain it but I’ve bought batteries brand new from the store which were dead in months on the floor. I’ve had batteries that worked perfectly which sat on the concrete for a year that was dead. I’ve even had 2 brand new batteries from the same store same lot and the one that sat on the ground was dead with in a year. You might not have been able to test it but from my experience it does. Again I can’t explain it but brand new batteries have died for me from the floor

[@ToolDemos]

kzbin.infoTLYG9jU0gT0?si=AQnSXLAN5H7pdR_d

[@anthonygm85]

I've always found most ohm or even voltage leaks around the top caps and I can trace it from high to low

[@ToolDemos]

Yeah, someone else mentioned that it could be from a vent leak.

[@JamieBainbridge]

The reason I was told is that dust settles on the top and creates a very high resistance circuit between the terminals which drains the battery over time, like connecting a small bulb would do (but faster). Made sense because we were always grinding, filing, cutting, welding, making metal dust. I don't know if the reasoning is true, but I always give any spare car battery a wipe so it doesn't get dusty.

[@ToolDemos]

That I believe could happen. Especially with metal dust.

[@kissmezombie]

Agree