Lead acid battery facts for kids

A lead-acid battery is a special kind of battery that you can use over and over again by recharging it. You'll find them in many cars and trucks because they are great at providing a lot of power quickly.

Lead acid battery in a car

How a Lead-Acid Battery Works

Inside a lead-acid battery, there are plates made of lead and another material called lead(IV) oxide. These plates sit in a liquid called sulfuric acid. When the battery is working, the lead(IV) oxide reacts with the lead plate. This reaction creates an electrical current, which is the power that makes things work.

Why These Batteries Are Popular

Lead-acid batteries are often the cheapest type of rechargeable battery you can buy. They can also produce a lot of power very quickly, which is why they are perfect for starting car engines.

Important Things to Know About Lead-Acid Batteries

• Recycling is Key: These batteries contain lead, which is a toxic metal. This means they can be harmful to the environment if not handled properly. It's very important to recycle lead-acid batteries when they are old.
• Wet Cells: Most lead-acid batteries are "wet cells." This means they contain liquid sulfuric acid, which can be dangerous if it spills.
• Sealed Batteries: To make them safer, some lead-acid batteries are "sealed." In these, the sulfuric acid is mixed into a gel. This gel stays inside the battery, even if you turn it upside down, making them less likely to spill.

The Chemistry Inside

When a lead-acid battery gives power, these chemical changes happen:

• The lead(IV) oxide, sulfuric acid, and some extra hydrogen ions turn into lead(II) sulfate and water at one part of the battery (the cathode).
• The lead and extra sulfate ions turn into lead(II) sulfate at the other part (the anode).

When you charge the battery, these reactions happen in reverse, putting the battery back to its original state so it can be used again.

Images for kids

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  Fully discharged: two identical lead sulfate plates and diluted sulfuric acid solution

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  Fully recharged: Lead dioxide positive plate, Lead negative plate, and concentrated aqueous sulfuric acid solution

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  A hydrometer can be used to test the specific gravity of each cell as a measure of its state of charge.

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  Internal view of a small lead–acid battery from an electric-start equipped motorcycle

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  Charge current needs to match the ability of the battery to absorb the energy. Using too large a charge current on a small battery can lead to boiling and venting of the electrolyte. In this image a VRLA battery case has ballooned due to the high gas pressure developed during overcharge.

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  Sulfated plates from a 12-V 5-Ah battery

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  Car lead–acid battery after explosion showing brittle fracture in casing ends

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  A worker recycling molten lead in a battery recycling facility

See also

In Spanish: Batería de plomo y ácido para niños