Car Battery Glossary
Learn the basics.
Explore common terms you’ll come across when choosing, replacing, or maintaining a car battery.
A–F
AGM (Absorbent Glass Mat)
A type of battery where the electrolyte is held in glass fiber mats. Known for long life, fast recharging, and durability in stop-and-go traffic.Alternator
Charges your battery and powers electrical systems while the engine is running.CCA (Cold Cranking Amps)
A measure of a battery’s ability to start your car in cold weather.Corrosion
A white or bluish buildup around battery terminals that can interfere with performance. It’s caused by acid vapors and moisture.Cranking Amps (CA)
Similar to CCA but measured at 32°F. Indicates starting power in moderate weather.G–P
Lead-Acid Battery
The most common type of car battery. Uses lead plates and sulfuric acid to generate power.Maintenance-Free Battery
A sealed battery that doesn’t need you to add water or check acid levels.Negative Terminal
Marked with a “–” sign, it connects the battery to the car’s chassis ground.Positive Terminal
Marked with a “+” sign, it connects the battery to the starter and electrical system.R–Z
Reserve Capacity (RC)
How long the battery can run your car’s systems if the alternator fails—measured in minutes.Sulfation
Crystals that form on lead plates when a battery is undercharged, reducing performance and lifespan.Terminal
The connection points (positive and negative) on top or side of the battery.Voltage
A measure of the battery’s electrical potential. Most car batteries are 12 volts.
Pro Tips
Not sure which battery you need? Visit our Battery Finder tool.
Find Your BatterySee signs of corrosion or slow starts? You might be due for a replacement.
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