A lead-acid battery stores and releases energy through a chemical reaction between lead and sulfuric acid. When the battery is charged, the lead and sulfuric acid react to form lead sulfate and water, storing energy in the battery.
A typical lead–acid battery contains a mixture with varying concentrations of water and acid. Sulfuric acid has a higher density than water, which causes the acid formed at the plates during charging to flow downward and collect at the bottom of the battery.
The lead–acid battery is a type of rechargeable battery first invented in 1859 by French physicist Gaston Planté. It is the first type of rechargeable battery ever created. Compared to modern rechargeable batteries, lead–acid batteries have relatively low energy density. Despite this, they are able to supply high surge currents.
The electrolyte in a lead-acid battery is sulfuric acid, which acts as a conductor for the flow of electrons between the lead plates. When the battery is charged, the sulfuric acid reacts with the lead plates to form lead sulfate and water.
The working principle of a lead-acid battery is based on the chemical reaction between lead and sulfuric acid. During the discharge process, the lead and lead oxide plates in the battery react with the sulfuric acid electrolyte to produce lead sulfate and water. The chemical reaction can be represented as follows:
Charging is now required. One not-so-nice feature of lead acid batteries is that they discharge all by themselves even if not used. A general rule of thumb is a one percent per day rate of self-discharge. This rate increases at high temperatures and decreases at cold temperatures.