Automotive batteries are electrochemical energy storage devices providing initial electrical power for starting the engine and ongoing power for electrical systems when the alternator is insufficient. Typically located in the engine compartment, they deliver direct current (DC) electricity via a lead-acid, AGM, or lithium-ion chemical composition. Key specifications include cold cranking amps (CCA), reserve capacity (RC), and terminal configuration, dictating performance in varying temperatures and electrical load conditions. Modern batteries often incorporate internal sensors communicating battery state-of-charge and health data via the vehicle’s data bus. Proper venting systems are critical for lead-acid designs to manage hydrogen gas produced during charging.