This question touches on the nature of electricity, current, and how they affect the human body. At first glance, a 12-volt battery seems to be the same regardless of its context—household or car. However, the critical difference lies not in the voltage itself but in the power capacity and how each battery delivers that power.
A typical household battery, like those found in a remote control or flashlight, has a low current capacity and limited energy output. These batteries usually provide only enough current to power small devices, and the energy available is relatively low, making it difficult for them to deliver a shock that could be harmful.
In contrast, a car battery, even though it is also rated at 12 volts, is designed to provide a much higher current. Car batteries are usually lead-acid types and can deliver hundreds of amps of current when needed to start an engine. This high current can cause significant and rapid muscle contraction, potentially leading to severe injuries or death if the current flows through a vulnerable part of the body, such as the heart.
Moreover, the risk of electric shock also relates to how the contact with each battery is made. Car batteries are often connected through metal clamps, and if someone were to touch the terminals while having wet skin or other conditions that lower their resistance, the chance of receiving a dangerous shock increases dramatically.
To sum up, the danger from a 12-volt car battery comes from its ability to deliver a much higher current compared to a household battery. It’s not the voltage alone that is dangerous—it’s the available current that can lead to life-threatening situations.