Lead–acid battery

Some batteries can be used again.

This is a special kind of battery. It was the first one ever made.

It helps start cars. It can also power lights in trains.

Inside, it has metal plates. These plates sit in a special liquid. This liquid helps the battery work.

When the battery is used, the liquid changes. It becomes mostly water. To fill the battery, you must charge it. This can take many hours.

Some batteries use a thick gel. This gel stops the liquid from leaking out. It can work in any position.

These batteries are very useful today. They are not too expensive to make.

A lead–acid battery is a type of rechargeable battery.

This means you can use it and then charge it again. A French scientist named Gaston Planté made the first one in 1859. It was the very first rechargeable battery ever made.

These batteries are very useful for cars. They can give a big burst of power to start an engine. They are also not very expensive. Because of this, many people use them. They are also used to keep power running in hospitals.

Inside the battery, there are metal plates. These plates sit in a liquid called an electrolyte. This liquid is made of water and sulfuric acid. When the battery is full, the plates are made of lead and lead dioxide. When the battery is used, the plates change into lead sulfate. The liquid also changes and becomes mostly water.

To check if a battery is full, people use a tool called a hydrometer.

This tool measures how heavy the liquid is. A full battery has more acid, so the liquid is heavier. Charging a dead battery can take 6 to 12 hours.

A lead–acid battery is a special kind of rechargeable battery. This means you can use the energy and then refill it later.

These batteries are very helpful for motor vehicles. They can provide a high surge current, which is a big burst of power. This burst helps start the engine of a car. Even though they are heavy and hold less energy than newer types, they are still very useful. They are also quite cheap to make.

Inside the battery, a way it works involves two different metal plates. These plates sit in a liquid called an electrolyte. This liquid is a mix of water and sulfuric acid.

When the battery is fully charged, one plate is made of lead and the other is lead dioxide. The liquid has a lot of sulfuric acid in it. When you use the battery, the plates change into lead sulfate. The liquid also changes and becomes mostly water.

History shows us how these batteries first began. A French scientist named Gaston Planté invented the first one in 1859.

His first model used two lead sheets rolled into a spiral. These sheets were separated by rubber strips and sat in acid. Later, in 1881, Camille Alphonse Faure made an improved version. He used a lead grid with a paste on it. This made the batteries much easier to mass-produce.

There are many interesting facts about these batteries. In 1999, they made up about 40% to 50% of the value of all batteries sold worldwide. This was worth about US$15 billion.

Most car batteries take 6 to 12 hours to charge fully. They usually last for less than 500 deep cycles. Some special versions, called VRLA batteries, use a gel instead of a liquid. These can be used in any position without leaking. They are often used to keep power running in hospitals.

You might see these batteries in many places today. They are used in cell phone towers to provide backup power. They are also used in large emergency power systems.

You can even check if a battery is full using a tool called a hydrometer. This tool measures how heavy the liquid is. If the liquid is heavy, it has more acid and is more charged. This is a simple way to see if the battery is ready to work.

A lead–acid battery is a type of rechargeable battery used to store chemical energy. It is an essential tool for modern life, particularly for starting engines in motor vehicles. These batteries are valued because they can supply high surge currents, which are large bursts of electrical power. While they have a lower energy density and are heavier than newer battery types, they remain very cost-effective.

Because they are inexpensive, they are widely used even when higher energy density is available from other designs.

The mechanism of a lead–acid battery relies on electrochemical reactions between two plates and an electrolyte. The electrolyte is a liquid solution containing about 10 percent sulfuric acid. In a fully charged state, the negative plate consists of metallic lead. The positive plate is made of lead dioxide. The electrolyte is a concentrated aqueous sulfuric acid solution, which stores most of the chemical energy.

When the battery discharges, the chemical energy is converted into electricity through a specific sequence of steps.

During discharge, the negative plate reacts with the sulfuric acid to produce lead(II) sulfate and hydrogen ions. This reaction releases two conduction electrons, giving the electrode a negative charge. Simultaneously, the positive plate reacts with the sulfate ions and electrons to also form lead(II) sulfate. As these reactions occur, the electrolyte loses much of its dissolved sulfuric acid and becomes primarily water.

Consequently, both plates become lead sulfate, and the electrolyte's density decreases. This process can be summarized as lead and lead dioxide reacting with sulfuric acid to create lead sulfate and water.

There are several distinct types of lead–acid batteries designed for different needs. Standard "flooded" batteries use a liquid electrolyte that can be inspected and topped up with pure water. To prevent leaks, some designs use a gel electrolyte instead of a liquid. These are known as valve-regulated lead–acid (VRLA) batteries. VRLA batteries include gel cell and absorbed glass mat (AGM) types. These specialized versions are common in telecommunications networks and hospital emergency systems because they can operate in many positions without leaking.

The history of this technology began with observations by Nicolas Gautherot in 1801. He noticed that wires used in electrolysis could provide a small secondary current. However, the first true rechargeable battery was invented in 1859 by French physicist Gaston Planté. His original model used two lead sheets rolled into a spiral and separated by rubber strips. In 1881, Camille Alphonse Faure improved this by creating a lead grid lattice. He pressed a lead oxide paste into the grid, which made the batteries much easier to mass-produce.

Lead–acid batteries have significant economic and technical specifications. In 1999, their sales accounted for 40% to 50% of the total value of batteries sold worldwide, excluding China and Russia. This represented a manufacturing market value of approximately US$15 billion. Most automotive batteries require between 6 and 12 hours to charge fully from a discharged state. They also have a relatively short cycle lifespan, usually lasting less than 500 deep cycles.

Understanding the state of charge is vital for managing these systems. One can use a hydrometer to measure the specific gravity of the electrolyte. As the battery discharges, the specific gravity falls because the acid concentration decreases.

Another method is to measure the open-circuit voltage. For a single cell, the voltage ranges from 1.8 V when fully discharged to 2.10 V when fully charged. These measurements help ensure the battery is healthy and ready to provide power for critical systems.