can a car battery sit on concrete

[OJake]

Yes, a modern car battery can sit on concrete without any issue. The belief that it will drain the battery is a long-standing myth that originated decades ago with early battery designs. Today's automotive batteries have polypropylene cases that are excellent insulators, preventing any external electrical discharge to the ground. The primary concerns for battery storage are temperature extremes and maintaining a proper charge, not the surface it rests on.

The myth likely stems from the early 20th century when batteries had cases made of porous materials like hard rubber or tar-lined wood. If the outer case became damp and conductive from electrolyte seepage, it could potentially allow a slow discharge path if placed on a conductive surface like concrete. Modern sealed batteries, including Absorbent Glass Mat (AGM) and flooded lead-acid types, completely eliminate this problem.

The real factors that drain a stored battery are:

• Parasitic Draw: Small, constant drains from the car's computer, clock, or alarm system.
• Temperature: High heat accelerates the battery's internal chemical reaction, leading to self-discharge, while extreme cold reduces its ability to hold a charge.
• Age: An older battery will naturally self-discharge faster.

For optimal long-term storage, the Battery Council International (BCI) recommends disconnecting the battery from the vehicle and using a battery maintainer or smart charger to keep it at a full state of charge. Storing it in a cool, dry place is far more important than what it sits on.

Battery Type	Case Material	Susceptibility to Discharge from Concrete	Key Storage Consideration
Modern Flooded Lead-Acid	Polypropylene	None	Check fluid levels; use a maintainer
AGM (Absorbent Glass Mat)	Polypropylene	None	Very low self-discharge; a maintainer is still ideal
EFB (Enhanced Flooded Battery)	Polypropylene	None	Common in start-stop systems; use a maintainer
Early 20th Century Batteries	Hard Rubber/Tar-lined Wood	Possible (if case was damp/contaminated)	Historical context for the myth

[Winter]

Absolutely. That's an old wives' tale from my grandpa's day. Batteries back then were built differently and could leak, which caused problems. The ones we have now are made of super tough plastic that doesn't let any electricity escape. I keep my spare motorcycle battery right on the garage floor. The concrete won't hurt it; letting it sit for months without a trickle charger is what will kill it.

[OSpencer]

As a mechanic, I can confirm this is a myth. I've left countless batteries on the shop concrete floor overnight with no effect. The real danger is sulfation, which happens when a battery sits discharged. If you're storing a battery, just make sure the terminals are clean and it's hooked up to a float charger. That's the professional advice that actually matters.

[JulianaLee]

I believed that myth for years until I actually looked into it. The concern made sense for really old technology, but it's completely irrelevant now. Think about it: the battery is already in a metal tray in your car, which is just as conductive. The plastic case is designed to prevent this. You're better off worrying about cleaning any corrosion off the terminals and keeping it away from space heaters.

[MacMiles]

I store my classic car battery on a wooden shelf, but that's just for organization. The concrete floor itself isn't the problem. The issue is that any battery, whether on a shelf or concrete, will slowly lose its charge if left disconnected. For long-term storage, the single best thing you can do is connect a battery maintainer. It provides a tiny trickle of power to counteract self-discharge, which is the true enemy of a stored battery.