Dec 22, 2025
How a Car Battery Works: Components & Functions
Discover how a car battery works, from its lead-acid cells and chemical reactions to the power it delivers for starting, lighting and ignition (SLI). Learn how sulphuric acid and lead plates generate and supply energy, why the alternator takes over once the engine starts, and how battery capacity affects performance. This guide also explains common functions, why batteries wear out, and the importance of timely maintenance and replacement.