Car Batteries are rechargeable lead-acid batteries that power the vehicle’s starting, lighting and ignition (SLI) system. They have removable caps to allow for maintenance, like topping off with distilled water.
Three traditional measures to consider when choosing a battery include its BCI group number, size and warranty. The group number specifies the battery’s dimensions to ensure it fits properly in your car’s battery tray.
Size
Car batteries come in various sizes and electrical capacities, so you want to make sure you’re picking one that fits your vehicle and can handle its power demands. Fortunately, finding the right battery is easier than you might think. Simply look in your owner’s manual or check out an in-store fit guide before shopping.
Most American vehicles use a standard top post battery with terminals on the front of the battery case. These are also known as flooded or conventional batteries. They are low maintenance and require a topping off of distilled water from time to time.
Most European cars use a recessed top post battery. These batteries have cable ends that screw into the sides of the battery, and they’re typically installed in the trunk or under the back seat (as opposed to under the hood). These batteries are low maintenance and require regular filling with distilled water. They also have a higher charging acceptance rate.
Capacity
The capacity of car batteries is the amount of electric energy they can store. A battery’s capacity is measured in amp-hours. The higher the rating, the longer it can be used before it needs to be recharged.
Batteries are a crucial source of power to all the electric components in your vehicle. They provide the jolt needed to start the engine and help run power-hungry accessories like the radio, heater and lights when the car isn’t in use.
The usable portion of battery capacity generally aligns with the car’s indicated state of charge (0-100 percent). It may also include a reserve capacity that helps guard against stranding if you accidentally discharge the battery or overcharge it. Battery capacities are dynamic, and they deteriorate over time due to age, temperature and other factors. Getting your battery serviced regularly can help preserve its health and boost your car’s performance.
Weight
The weight of a car battery may seem like an irrelevant detail to many, but it has far-reaching implications for automotive performance and design. Heavier batteries can put an unnecessary strain on suspension and other components, while lighter ones can improve agility.
Battery weight is determined primarily by the density of its lead plates and electrolyte solution. The latter is a solution of water, sulfuric acid, and other chemicals that facilitate the chemical reactions necessary to produce electricity. Additionally, the battery’s plastic or metal casing contributes to its total weight.
Some battery types are also designed with a focus on energy density. This is especially true for lithium-ion batteries, which offer a greater power output and longer cruising range than standard lead-acid units. These types of batteries typically have denser positive plates to improve cycling capabilities and offer a reduced overall mass. While they generally have a higher price tag, these batteries are ideal for electric vehicles and other applications that require high-power outputs over long periods of time.
Installation
Car batteries are used to supply a steady stream of power to the vehicle’s electrical systems. They also help to absorb sudden power spikes and instabilities that can cause damage to solid-state electronics, such as the vehicle’s computer and radio. They are made of several cells connected by short, heavy straps that correspond to the positive and negative plates in each cell. Lead-acid units are the most common, but newer models with features like fuel-saving start/stop technology are now deploying lithium-ion batteries.
To check your battery’s voltage, make sure the car is turned off and pop the hood to expose the terminals. Put on insulated work gloves and safety goggles before you touch the exposed battery’s terminals. Then, set your multimeter to its DC voltage setting (most read up to 20 volts). Connect the red probe of the meter to the battery’s positive terminal and the black probe to the negative terminal. A reading of 12.6 to 12.8 volts indicates a healthy battery.