The battery is the central power source for your motor vehicle. It consists of several cells with lead and/or lead dioxide plates saturated in sulfuric acid. A series of chemical conversions between the plates creates ions that flow into the terminals to generate electric current.
Most cars have a built-in alternator to supply electricity, but in extreme situations — say driving your SUV on a hot summer road with the air conditioning and wipers on — the alternator may not be able keep up. That’s where an uprated battery comes in.
Battery Group Number
The battery group number is the first piece of information you need to know when shopping for a new battery. This code, created by the Battery Council International (BCI), defines the physical dimensions and terminal positions of your vehicle’s battery.
It’s important to have the right battery for your car, truck or SUV because each type has different power requirements. For example, you might need a battery with a minimum CCA to start your engine or a higher CCA to run multiple electrical systems like the radio and heated seats.
Look for the BCI group number on your existing battery or check the owner’s manual. The number can be hidden or hard to read but it’s usually printed on the top and/or front of the battery.
Cold Cranking Amps (CCA)
Cold cranking amps, or CCA, are a vital metric to consider when selecting a battery. It is the amount of current a battery can deliver for 30 seconds at 0degF while maintaining terminal voltage of 7.2 volts.
Car batteries with a high CCA rating can overcome engine starting challenges in cold environments. For example, cold temperatures increase the viscosity of engine oil and can create additional resistance during startup. A battery with a high CCA can provide the extra power needed to overcome these challenges.
However, CCA shouldn’t be your sole selection criterion. Other important metrics to consider include reserve capacity and life span. You should also consult your vehicle owner’s manual to determine the recommended battery specifications for your car. Having an understanding of these specifications will help you select the right battery for your car and prevent unnecessary battery replacement.
Size
The battery size refers to the physical dimensions of the battery (length x width x height) and is an industry standard set by Battery Council International. It makes shopping for a replacement battery at your local Firestone Complete Auto Care easy by making it easier to find a model that fits your car. However, the physical size alone isn’t enough – you also need to make sure the new battery has the correct cold cranking amps (CCA) for your vehicle.
The right sized battery will fit snugly in the vehicle’s battery holding tray, and it should have the same chemistry as your old one. Other characteristics to look for are the reserve capacity and the position of the terminals. Those aren’t as crucial for the everyday driver but can be important in high-performance cars.
Terminals
Powering everything from high-tech sensors to machine-precise fuel control, cars require a lot of electricity. The battery provides it, and the terminals connect it to other car parts like the alternator.
Most automotive batteries have one of three types of terminals. SAE post terminals are the most common, consisting of two lead posts in the shape of truncated cones, positioned on the top of the battery, with slightly different diameters to ensure correct electrical polarity connections.
Other terminals have a side-post design, which saves space under the hood and are commonly used in GM vehicles. They’re often made of brass or copper, which provide excellent conductivity and corrosion resistance. They can be soldered or crimped. They also have a threaded hole that can accept various adapters for different cable sizes.
Type
Car batteries come in a variety of styles. Choosing the right one for your vehicle depends on power requirements and driving habits.
For example, some cars require a large amount of instantaneous current for starting the engine while others need an alternator to keep providing energy for electric accessories such as the air conditioner and wipers. A battery designed for starting the engine is known as an SLI (starting, lighting and ignition) battery.
Lead-acid batteries are the workhorses of car engines worldwide. They have a simple design that includes a case that holds a series of lead plates bathed in an acid solution that creates electricity. Most are classified as wet-cell batteries and can be opened to add distilled water when necessary. The battery also contains features that help control developing voltage to prevent damage.