Even though your car’s battery might seem simple, it’s quite complex and important. Anyone who’s needed a jumpstart understands the critical role the battery plays in getting (and keeping) your car running.
But what is the battery really, and how does it work? The answer isn’t as straightforward as you might think.
There’s a lot of chemistry going on inside an automotive battery, but don’t worry—we’ll leave out those confusing formulas you used in high school.
Here’s how a traditional, lead-acid battery works, in layman’s terms:
While supplying electricity to the vehicle, the battery begins to discharge. That means the sulfuric acid starts to move from the electrolyte to the plates.
The discharge process causes the electrolyte to start losing sulfuric acid, so the battery’s output voltage is reduced. For this reason, an alternator is used to recharge the battery when the car is running.
Recharging the battery removes the sulfuric acid from the plates, restoring the electrolyte to a normal-strength solution.
Lead-acid batteries are sometimes referred to as “storage batteries” because they are repeatedly discharged and must be recharged by the alternator.
Batteries have several ratings, all of which reference the battery’s capacity—the amount of electrical energy that the battery can provide under select conditions.
The capacity primarily depends on the number of plates used inside the battery’s cells.
The different car battery ratings include:
The CCA rating is the most common battery rating method. It indicates the number of amps a 12-volt battery can deliver for 30 seconds at 0 degrees Farenheight without falling below 7.2 volts.
The CA rating indicates the number of amps a 12-volt battery can deliver for 30 seconds at 32 degrees Farenheight without falling below 7.2 volts. The CA rating is essentially the same thing as another type of rating called the marine cranking amperes.
The ampere-hour rating (an older measurement method) indicates how many amps the battery can deliver over a given period of time.
The reserve capacity is the length of time (measured in minutes) that a 12-volt battery can supply 25 amps before dropping below 10.5 volts.
Another important factor is the group size of the battery. The correct group size ensures the battery will physically fit inside a particular vehicle.
You can find the correct size for your application by looking in the owner’s manual. The group size will also be listed somewhere on the battery.
The battery in your car serves two primary functions:
The battery also acts as a capacitor to smooth out current ripples and protect the vehicle’s sensitive onboard electronics.
Two cables (a negative and a positive) connect the battery to the car. The negative cable connects to a common ground, while the positive cable connects the battery to the starter motor and other necessary points on the vehicle.
Some people wonder whether a car battery produces alternating current (AC) electricity or direct current (DC) electricity. The answer is: automotive batteries always produce DC voltage.
The alternator, on the other hand, produces AC voltage. That’s why the alternator must contain semi-conductors, called diodes, that convert the alternating current to direct current.
In case you were wondering, the difference between AC and DC is that direct current flows in only one direction, whereas alternating current reverses directions repeatedly. Because of this, AC produces a sinusoidal waveform pattern, and non-pulsating DC produces a straight line pattern.
So far, we’ve discussed traditional lead-acid batteries. But there are other types of 12-volt automotive batteries as well. Common types include:
Most 12-volt automotive batteries are of the lead-acid variety. This type of battery is also known as a flooded lead-acid (FLA) battery because it contains a liquid electrolyte.
Another design becoming increasingly common is the AGM battery. Instead of using a liquid electrolyte, the acid in an AGM battery is absorbed into the separator.
Typically, this type of battery is used in applications with high charging capacities.
EFB batteries are used in vehicles that feature engine start/stop technology. Basically, an EFB is a type of flooded battery that’s more robust than a traditional lead-acid battery.
Car batteries don’t last forever. Their lifespan will vary depending on several factors, but you can expect them to last around three to four years. If you find any issues with your car battery, then you might have to replace it even sooner unless you want to risk getting stranded with a dead battery. Luckily, finding a new battery is fast and easy with CarParts.com.
CarParts.com offers a wide selection of car batteries, all sourced from the most trusted manufacturers in the industry. Easily browse through our catalog using our vehicle selector and search filters. Just be sure to input your vehicle’s correct details. If you’re itching to get back on the road, you’ll be pleased to know that CarParts.com also guarantees fast shipping. Order by 12 p.m. ET, and you can expect your new battery to arrive in as fast as two business days.
Don’t wait until your car battery dies and leaves you stranded before getting a new one. Check out our selection of high-quality batteries at CarParts.com and order yours today!
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.