How a lead acid battery works

9 September 2024

Learning about the inner workings of lead acid batteries, their electrochemical processes, and operational states is key to understanding their functionality.

The principles of electricity

Electricity is the lifeblood of modern technology, flowing through conductors like copper wires in the form of electrons. In lead acid batteries, this flow is harnessed to generate voltage, measured in Volts, and current, measured in Amps.

What is a battery?

A battery serves as a reservoir of electrical energy stored in chemical form, capable of controlled release when needed.

There are two types of battery, primary which are used until discharged and then disposed of, like the ones in the TV remote, and secondary which can be recharged and reused, like the one in your phone.

Lead acid batteries, a common secondary type, consist of positive and negative electrodes, which take the form of plates, immersed in an electrolyte solution of sulphuric acid. This chemical composition enables efficient energy storage and discharge, making lead acid batteries abundant in various applications.

Generating a voltage

The generation of voltage is a crucial aspect of battery functionality, driving numerous electronic devices and systems. When connected to an electrical circuit, the ongoing chemical reaction between the negative plates and the electrolyte increases substantially, creating a potential difference and electron flow between the positive and negative plates. This released electrical energy powers external devices, causing battery discharge.

Group of Yuasa, GS, and GS Yuasa automotive batteries in a workshop setting

Electrochemical reaction during discharge

During discharge, the sulphuric acid breaks down, releasing positively charged hydrogen ions and negatively charged sulphate ions. The flow of electrons through the external circuit powers devices, while lead and sulphate ions combine to form lead sulphate and oxygen ions. Battery discharge is a dynamic process influenced by factors such as load demand and internal resistance, affecting overall battery performance.

Electrochemical reaction during recharge

Recharging reverses the chemical processes of discharge, forcibly removing electrons from lead sulphate atoms and replenishing the electrolyte with hydrogen and oxygen ions. This restores the battery's stored electrical energy for future use. Proper charging procedures are essential to maintain battery health and maximise lifespan, emphasising the importance of understanding the recharge process.

Battery discharging & charging characteristics

Battery discharging occurs continuously, with sulphate and hydrogen ions present in the electrolyte solution. Self-discharge, influenced by temperature and usage patterns, gradually depletes a battery's capacity over time. When recharging, careful management to avoid overcharging and electrolyte depletion is necessary, this is why GS Yuasa always recommend the use of a smart charger.

By grasping the intricate electrochemical processes and operational states outlined in this guide, you'll be better equipped to harness the power of lead acid batteries effectively.

GS Yuasa Battery Europe Ltd

GS Yuasa are one of the world’s largest global manufacturers of Lead-Acid and Lithium-ion (Li-ion) batteries. For over 30 years, GS Yuasa Battery Europe Ltd have been Europe’s leading battery supplier and the number one choice for quality, performance and reliability.

GS Yuasa Battery Europe Ltd consists of five sales companies and one battery manufacturing company.