Glossary of Terms

An advanced type of lead-acid battery that holds its electrolyte in absorbent glass-fibre mats between the battery plates. AGM batteries are designed to handle repeated charging and discharging, making them suitable for many vehicles with start-stop systems and higher electrical demands.

Amp-hours (Ah) measure a battery's electrical charge capacity, indicating how much current it can supply over a specified period. For example, a 60 Ah battery can theoretically deliver 3 amps for 20 hours under specified test conditions. A higher Ah rating generally means a battery can supply electrical current for longer under comparable conditions.

A component that generates electricity while the engine is running. It supplies power to the vehicle's electrical systems and helps recharge the battery.

Two important measures of a car battery's performance. Capacity, measured in amp-hours (Ah), indicates how much electrical charge a battery can deliver over time. Starting performance describes the battery's ability to supply the high electrical current needed to start the engine, commonly measured in cold cranking amps (CCA).

The components responsible for generating and regulating electrical power while the engine is running. These typically include the alternator and voltage regulator, which work together to power the vehicle's electrical systems and recharge the battery.

The process of turning the engine over using the starter motor when starting a vehicle. The battery must deliver enough electrical current to crank the engine successfully.

An improved type of conventional flooded lead-acid battery designed to withstand more frequent charging and discharging. EFB batteries are commonly used in vehicles with basic start-stop systems and offer greater cycling durability than standard flooded batteries.

The substance inside a battery that allows electrically charged particles to move between its internal components during charging and discharging. In lead-acid car batteries, the electrolyte is a mixture of sulphuric acid and water.

An electronic vehicle security system that prevents the engine from starting unless the correct key or authorised electronic signal is detected. It helps protect the vehicle against theft.

A vehicle system that automatically switches off the engine when the car comes to a stop, such as at a traffic light, and restarts it when the driver is ready to move. Start-stop vehicles generally need specially designed batteries that can handle frequent engine restarts.

An electric motor that uses power from the battery to turn the engine when you start your car. It gets the engine moving until it can run on its own.

The position of the positive (+) and negative (−) terminals on a car battery. The correct terminal layout ensures the battery cables can connect safely and properly when the battery is fitted.

A specific version of a vehicle model, which may differ in engine size, features, equipment or electrical requirements. Different variants of the same car model may require different batteries.