can shorted car battery test good

[HannahAnn]

No, a standard voltage test alone cannot reliably determine if a car battery is good if you suspect an internal short circuit. An internal short occurs when the battery's lead plates touch or the separator between them fails, creating an unintended path for current. While a surface charge might show a normal 12.6 volts, the battery will fail dramatically under load because the short prevents it from holding a charge and delivering the necessary amperage (cranking amps) to start your engine.

The most accurate way to diagnose a shorted battery is through a load test. This test applies a simulated engine-starting load to the battery while monitoring its voltage. A healthy battery will maintain voltage above a specified threshold (usually 9.6 volts) for the duration of the test. A shorted battery's voltage will drop precipitously. Many auto parts stores offer this test for free.

Symptom/Test	Healthy Battery Indication	Shorted Battery Indication
Resting Voltage	12.4 - 12.7 volts	May show 12.6V initially, but drops rapidly
Load Test Voltage	Stays above 9.6V for 15 seconds	Drops sharply below 9.6V
Hydrometer Test	All cells show similar specific gravity	Significant variance in specific gravity between cells
Battery Surface Temp	Cool to the touch	May feel warm or hot due to internal discharge
Recharge Behavior	Holds charge for days/weeks	Dies overnight or within hours after charging

Other signs of an internal short include a battery that feels warm when the car is off, or needing to constantly jump-start the vehicle even after a long drive. If you experience these symptoms, a professional load test is the definitive next step.

[AmirFitz]

Been there. If you think the battery's shorted, a simple multimeter reading can trick you. It might show 12 volts, but the second you try to start the car, it's dead. That's the short killing its power. The real test is a load test, which checks if the battery can actually handle the stress of starting the engine. Most auto shops will do this for free in a few minutes and give you a straight answer.

[McBrayden]

From a technical standpoint, a standard open-circuit voltage test is insufficient. An internal short creates a high self-discharge rate. The battery may read fully charged but lacks capacity. The definitive diagnostic procedure involves a capacity or load test, which measures voltage under a controlled amp load. Additionally, testing individual cell specific gravity with a hydrometer can reveal a bad cell, which is a common cause of an internal short.

[LaAshley]

My old truck's battery was acting up—would die overnight. I charged it, and the voltmeter said it was fine. But it was useless in the morning. The guy at the shop explained it was probably a short inside the battery itself. It's like having a leaky bucket; you can pour water in, but it never stays full. They hooked it up to their tester, and it confirmed it couldn't hold a charge under pressure. Had to replace it.

[SanJessica]

You're asking the right question. A surface test is not enough. The key is observing behavior over time. If you charge the battery fully and it goes dead in a day or two without being used, that's a huge red flag. Combine that with a voltage reading that looks okay but a car that won't crank, and the evidence points strongly to an internal short. It's often more cost-effective to replace it than to waste time and money on repeated charging.