Can a Car Battery Shock You?

In the automotive world, very few questions are as rife yet controversial as this: “can a car battery shock you?” There are valid to say yes and no simultaneously, depending on the battery type, mode of contact, materials used to handle the battery, etc.

This article will focus on the regular 12V lead-acid battery, the most common cell in today’s cars. It’ll explain the risks involved with this kind of battery and give tips for handling most battery types you’ll come across.

Why Don’t Batteries Shock You?

In case the subheading wasn’t already clear, a 12V battery will not shock you, at least not under normal circumstances. But why?

The voltage is the main reason you can safely touch your car’s battery terminals and walk away unhurt. While most car batteries have enough amperage to fry you, the voltage (12V) is not enough to cause harm.

This makes sense if you think of the voltage as pressure. So, although your battery has enough current to cause you significant harm, the 12 volts don’t provide enough pressure to push any serious amount of that current through the contact resistance of your skin. However, you may feel tingling if you touch the battery terminals with wet hands—that’s certainly not the life-threatening electrical torture you imagined.

Does That Mean 12V Batteries Are Harmless?

Your car battery may not be able to send muscle-wrecking electric shocks through your body, but it can still jeopardize your existence if proper care is not taken.  

Some of the biggest dangers associated with lead acid batteries are gassing and explosions. Gassing refers to a situation where the battery releases hydrogen sulfide (H₂S) gas when overcharged. The gas is colorless, flammable, poisonous, and smells like rotten eggs. It also accumulates at the bottom of poorly ventilated spaces due to its higher density than air.

On the other hand, explosions may occur from the accumulation of hydrogen and oxygen gasses. Hydrogen is colorless, odorless, lighter than air, and highly flammable, while oxygen can escalate fires or explosions. These gasses are usually locked up within sealed lead acid batteries like AGMs. But even in unsealed models, you have nothing to worry about unless you’re charging the battery in a poorly ventilated and sealed room. Hydrogen gas may accumulate near the ceiling, creating a fire or explosion hazard.

Another danger you can’t turn a blind eye to when talking about car batteries is inadvertently bridging the battery terminals with a wrench or other metal equipment. Unlike your body, a metal wrench has little resistance to electricity, and the battery will take advantage of this to pump a lot of current through it. This will make the wrench extremely hot and may even weld it in place. In the worst-case scenario, the battery could explode, spraying sulphuric acid all over.

This continues until and unless the battery fails, which will eventually happen as the rapid flow of electrons drains it, or the circuit becomes disconnected somehow. It’s bad news.

Lithium-ion Batteries Are an Entirely Different Matter

At the heart of the modern automobile era is lithium-ion batteries powering hybrid and electric vehicles, alongside conventional lead-acid batteries for the starter, lighting, and other smaller functions. And unlike their lead-based counterparts, lithium-ion batteries run at far larger voltages.

While a single lithium-ion cell may boast 3–4V, they’re often connected in series and parallel to form battery packs. An electric car may require 400–800V, while 100V-200V may suffice for a hybrid. You definitely don’t want to mishandle this one or even come close to it unless you’re a certified expert on the technology. Of course, in practice, the high voltage battery packs of hybrid and electric vehicles are well hidden, so you’re unlikely to come in contact with them unless you go searching.

It’s also worth noting that lead acid batteries are not the same. You must have noticed that the only reason why the typical lead-acid battery won’t shock you is that it’s rated at only 12V. However, not all car batteries have such low voltages. In the early 2000s, a large movement called for a move to higher voltage systems. However, while the switch never really happened, there are some 24V and even 36V batteries. If your car uses one of them, it’s better to be safe than sorry, especially if you consider that 30V is generally considered to be a conservative threshold value for dangerous voltage. 

What Are Some Tips for Working With Car Batteries?

It is important to show a high degree of caution when working with car batteries. Though you’re unlikely to be electrocuted under normal circumstances, mishandling batteries can be life-threatening. So, follow these tips when working with them:

• Wear gloves and other protective gear when performing any task involving car batteries. This should protect your hands from any acid leaks.
• Flush with excess water as soon as possible if you spill battery acid on your skin. Do the same and seek medical attention if the acid gets in your eyes.
• Do not overcharge your battery, as it could cause an explosion.
• Store car batteries in a cool, dry place. They’re capable of leaking acid if they get too hot.

Your Battery Won’t Shock You, but It’s Not Harmless

Can a car battery shock you? Now you know the answer is a no. However, while touching the terminals of your battery is not expected to electrocute you, an electric shock is not the only danger it poses. Be cautious when handling a battery during any inspection or change. And remember to always follow the manufacturer’s guidelines for battery care and handling, and direct any questions to a professional.

If you have a dead battery that needs replacing, follow our battery reconditioning guide to get a few more years out of it.

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