can car batteries get shorts

[LaAlan]

Yes, car batteries can absolutely develop a short circuit. This typically refers to an internal short circuit within the battery itself, which is a serious and potentially dangerous failure. It occurs when the insulating separators between the positive and negative lead plates inside the battery break down. This allows current to flow unrestricted through a path of least resistance, generating immense heat and rapidly draining the battery's charge.

An internal short is different from a short circuit in the car's wiring. A wiring short happens outside the battery, like when a tool accidentally bridges the positive and negative terminals. An internal short is a physical defect within the battery's sealed case.

The most common causes are physical damage (like a cracked case from an impact), extreme vibration over time loosening the internal components, or a manufacturing defect. Normal wear and tear, especially in harsh climates, can also degrade the internal separators.

Symptoms of a Shorted Battery:

• Rapid Discharge: The battery will go dead overnight or in a few hours, even with no electrical load.
• Swollen Case: Excessive heat from the short can cause the battery case to bulge or warp.
• Sulfuric Smell: You might notice a strong rotten egg smell, indicating the battery is overheating and venting gas.
• Hot to the Touch: The battery case will feel abnormally hot.
• Inability to Hold a Charge: Even after a jump-start or full charge, the battery voltage will drop quickly.

If you suspect an internal short, stop using the battery immediately. Do not attempt to jump-start or charge it, as this can lead to a thermal runaway event, where the battery overheats, potentially catches fire, or even explodes. The only solution is safe disposal and replacement.

Common Causes of Internal Shorts	Typical Symptoms	Critical Data/Evidence
Physical Impact/Damage	Battery drains completely in under 24 hours	A healthy battery loses ~1-5% charge per month; a shorted one drains in hours.
Excessive Vibration	Battery case is hot to the touch ( > 100°F / 38°C)	Normal operating temp is roughly 80-100°F (27-38°C).
Manufacturing Defect	Swollen or bulging battery case	Internal pressure buildup warps the plastic case.
Old Age / Wear	Strong sulfuric (rotten egg) smell	Caused by electrolyte boiling and venting hydrogen gas.
Overcharging	Will not hold a charge from a battery charger	A charger may show an error code or fail to complete a charging cycle.

[DelGavin]

Yep, they can, and it's bad news. I had it happen once. The car was dead every single morning. I'd charge it, and it'd be fine for a drive, but dead again the next day. The top of the battery felt warm even when the car was off. My mechanic told me the inside was basically fried—the plates were touching. Don't mess with it. Just get a new one. It's a fire hazard waiting to happen.

[OAaron]

An internal short circuit is a catastrophic failure mode for lead-acid batteries. It's not a simple fix. The internal resistance plummets, creating a direct path for current to flow uncontrolled. This generates excessive heat, accelerates plate sulfation, and causes rapid voltage drop. Diagnosing it requires a load test and a capacity test. The only safe and effective remediation is immediate replacement, as the structural integrity of the internal components is compromised beyond repair.

[LaylaRose]

Think of the inside of a battery like a deck of cards with dividers between each card. A short is when those dividers break down and the cards touch. When that happens inside the battery, it creates a tiny, super-hot spot that just drains all the power. You'll know it because the battery will keep dying no matter what you do, and it might even feel warm when it should be cold. It's toast at that point.

[EmilianoLynn]

Absolutely. An internal short is a definitive failure. The key sign is a battery that goes from fully charged to completely dead in a matter of hours, not days or weeks. If you hook up a multimeter, you'll see the voltage dropping steadily right before your eyes. This isn't something you can fix with a trickle charger. The constant internal drain damages the battery's core. For safety and reliability, swapping it out is the only smart move.