Guide to Car Batteries

What Are Car Batteries?

man removing battery from inside a car

Car batteries are what drive your vehicle and are arguably the most essential part of your car. It powers all of your car’s electricity and provides the spark that starts your vehicle. The main job of a car battery is to convert chemical energy into electrical energy. When it does so, it delivers the voltage to the starter to start the car.

Once your car has started, the car battery ensures that the voltage delivered to your engine is stable to keep it running. 

Car batteries last an average of 3 to 5 years, after which you may need to replace them. If you take proper care of it, it may last you even longer.

There are many different kinds of batteries available on the market, which is why you need to consider several factors before you purchase one. You must purchase a reliable and long-lasting one so you don’t need to replace it within a couple of years.

The Different Kinds of Car Batteries

Black battery with blue and red terminals

Knowing the kind of battery your car uses is imperative because it can save you a lot of hassle when it dies or breaks down. Understanding the different types of batteries ensures that you choose the one that will serve you best. There are five different kinds of car batteries available on the market.

Lead Acid Car Batteries

In most modern cars, you will find a lead-acid battery. These batteries are the most common type and get their name because they contain lead plates. These plates are intercalated with sulfuric acid and serve as electrodes. 

It is on these plates that the electrochemical reactions take place. The acid powers the engine because of a chemical reaction between it and other substances within the battery.

AGM Car Batteries

AGM stands for Absorbed Glass Mat batteries. They are similar to lead-acid batteries in their design but differ in two significant aspects. Firstly, AGM batteries lack a liquid electrolyte solution that lead-acid batteries have. Instead, AGM batteries use a sulfuric acid-soaked synthetic fiber mat, which serves as an electrolyte. Secondly, AGM batteries are sealed, and you don’t need to add water. 

AGM batteries are also maintenance-free, so when one deteriorates, you will most likely need to replace it as you can’t replace the acid or plates. To compensate, most AGM batteries have a larger ampere-hour rating as compared to standard lead acid batteries. 

Lithium-Ion Batteries

A lithium-ion battery are the most prevalent option for hybrids and electric cars. These batteries have high durability and power density, which makes them eco-friendly. A lithium-ion battery will serve you well if you want to switch to green energy to power your vehicle.

These batteries are designed to store more energy per volume. Furthermore, they also maintain near-constant voltage throughout their life cycle. Although lithium-ion batteries sound like the best battery type, you should consider the safety concerns before you purchase one.

EFB Battery

EFB batteries are an upgraded form of standard wet-flooded technology. They are much better than their predecessors because of the improved charge acknowledgment. These batteries also have greater cyclic toughness. When an EFB battery works in diminished charge conditions, it still performs quite well. EFB batteries are also great to opt for if you want long-lasting, high-efficiency ones. 

Valve-Regulated Lead Acid Batteries

Valve-regulated lead acid batteries are also called VRLA batteries. Instead of being vented, these batteries are sealed and do not emit flammable hydrogen gas when charging. Instead, VRLA batteries have a valve that controls the amount of oxygen released into the cells, making them different from other kinds of batteries.

The main advantage of such batteries is the reduced chance of a thermal runaway. However, if there is any damage to the valves, you will need to replace them, which can be costly.  

Starting, Lighting, and Ignition Batteries

Starting, Lighting, and Ignition batteries are also called SLI batteries. These kinds of batteries are not used for deep cycle purposes, and their battery life is not on par with that of AGM batteries.

SLI batteries are designed to offer a powerful burst of energy but only for a short duration, such as when you start your car.

These kinds of batteries are commonly found in hybrid or mild electric vehicles and are excellent at improving fuel efficiency. SLI batteries also reduce emissions and can withstand repeated cycle changes when driving at low speeds. They are also durable, and you can use them without the fear of experiencing degradation or swelling over time. 

The downside to such batteries is if one cell gets punctured while charging, the other cells are also likely to get damaged. Therefore, you will need to change the entire battery. Starting, Lighting, and Ignition batteries are used for short periods, so you can easily top off their water levels after charging. This method will prevent them from drying up. 

Ensure that you use distilled water to top them off because distilled water has additional minerals that replenish those lost. When adding new liquid, do not fill the gaps until the top is flush with the rest of the battery. Otherwise, it can cause an air bubble effect on one side if you add too much water at one time. 

If there are air bubbles, the cell balancing will be significantly affected, and your battery life will decrease. 

Different Sizes Available

Batteries come in various sizes, and you must choose one that fits under your hood. The terminals should also be placed correctly. Otherwise, the car cables may not reach them, and the battery will not be securely attached. 

Size Type of Cars
Size 75 General Motor cars
Size 65 Big-bodied Fords, Mercury and Lincoln cars
Size 35 Latest Toyota, Honda, and Nissan cars
Size 34 Chrysler cars
Size 34/78 Has 2 sets of terminals and can be used for some Chryslers and General Motor Models

What To Consider

Mechanic looking at car battery after removing it

When replacing your vehicle’s battery and buying a new one, you should keep certain factors in mind to ensure you get your money’s worth.

The Size of the Battery

The first and foremost thing to consider when purchasing a battery for your vehicle is its size. Car batteries come in various dimensions and have different widths, lengths, and heights. You should know the space available under your vehicle’s hood and the battery size that will fit best. 

If you have a larger car, use a car topside creeper to better assess the space you have under the hood.

Batteries also vary depending on the placement and type of terminals. It would be best if you aimed to find a battery that matches the electrical system in your car so that it fits perfectly and you don’t have to wiggle around the parts and make room for it.

To gain more information about the ideal battery size for your car, refer to the car’s manual, as it has all the information you need. If you are replacing your battery, the dimension of your old car’s battery can act as a reference guide. 

Manufacturing Date

When purchasing a car battery, always pick a fresh one. To determine how new a battery is, check the date stamp, which is usually on the top cover of the car battery. The date of manufacture is usually printed in the form of a two-character code. The letter symbolizes the month, and the number signifies the year of manufacture. 

Avoid purchasing a battery that is six months past its manufacturing date, and choose one that has been manufactured in the last month or two.

Sealed vs. Non-Sealed

There are two kinds of batteries in terms of maintenance. They are sealed and unsealed batteries. Sealed batteries are low-maintenance, as you cannot add water to them when they get too hot. Unsealed batteries are high maintenance as they have a cap at the top of the battery that you can use to add water. 

Unsealed batteries are an excellent choice if you live in a hot climate where the battery can heat up quickly. If the battery starts overheating, you can unscrew the top and add more water. Unsealed batteries do not provide that luxury, and you will have to wait till the battery cools before you can use your car again.


When purchasing batteries, ensure that you choose one offering a good warranty. Branded car batteries always provide a proper certificate that ensures repairs and replacement if an issue arises within a specific period. 

The two main factors to look for in warranties are replacement and prorated periods. A prorated warranty only allows partial reimbursement if your battery breaks down or the cells get damaged. 

Ideally, it would be best if you chose a battery with a warranty code 24/84. This code means that you can avail a free-of-cost complete battery replacement for 24 months if your battery gets damaged. The 84 stands for the prorated warranty that lasts an entire 84 months. 

Avoid purchasing batteries without a warranty because they usually do not last long. Shorter or no warranty hints that the company does not want to be held responsible if the battery breaks down. 

CCA and RC Ratings

When purchasing a battery, it is essential to look over their CCA and RC ratings. CCA refers to Cold Cranking Amps, a battery’s ability to start the vehicle’s engine in freezing temperatures. During the winter, batteries usually have a hard time igniting the car’s engine because the oil thickens, and the chemical reactions with the battery slow down.

The higher the CCA number of your battery, the better. If you live in an area with very cold winters, you should ensure that the CCA rating of your battery is high. A higher rating ensures that the car’s engine starts without an issue, regardless of the temperature. 

The RC rating, or Reserve Capacity, refers to how long a battery can function optimally if its alternator and rotor fail. One way to measure the RC number of your car is to see how long you can leave your headlights on. During this period, you should still be able to ignite the engine without needing to jumpstart the car with car battery chargers. 


New batteries cost around $100 to $400, with lower-performing SLA types at the lower end of the range. If you intend to purchase a higher-performing and long-lasting AGM battery, it will be much more expensive and on the upper end of the price range.

If you are replacing your car’s battery, be sure to take the older one to the retail outlet for recycling. Doing so can avoid a core charge, which is a mandatory deposit on your new battery.

Price Features
Under $100 Car batteries within this price range are decent and reliable in their performance, but they have a lower lifespan. You cannot find lithium or AGM batteries in this price range.
Between $100 and $200, Car batteries within this price range are powerful wet cell and AGM batteries. They last for 3 to 4 years and have a solid warranty.
$200 and up. Car batteries in this price range are dependable and durable. You can easily find AGM and Lithium batteries in this price range.

Maintenance of Your Car Battery

Car batteries are designed to last anywhere between 3 to 5 years, but if you take care of them, they can even last up to 10 years. Deterioration of the battery happens when you have long periods of inactivity, vibrations from rough roads, and many short journeys. You can also reduce the lifespan of your battery if you live in an area with temperature extremes. Experts suggest that during cold weather, batteries produce 35% less current. 

When extra strain is put on a car battery, the chemical reaction is disrupted, and a charge is generated. Look out for the warning light on your battery, which signifies that there is a problem with your battery. 

If your battery reads as dead, you have the option to recharge it using car battery chargers, but it is not a permanent solution. It will be enough to drive your car to a garage where a qualified mechanic will replace it. Ensure that you do not turn off the engine in such a situation.

After you have purchased a battery, you need to be attentive to its maintenance to ensure that it lasts long. The best way to maintain a battery is to test it annually. You should do routine maintenance every year, especially if you plan on taking a road trip. 

Most modern batteries are maintenance-free, meaning you do not need to top off their liquid often. However, professionals recommend that you have your battery load-tested by a mechanic once a year after two years have passed. This is extremely important if you live in a warmer climate. You can push off yearly checks for four years if you live in a colder climate. 

During load testing, you can measure the battery’s ability to hold voltage while being used. Such tests give you reasonable estimates of whether you should consider replacing your battery. You should also consider the date on the battery to determine whether or not you need to replace your battery. 

If you need to replace your battery, you should recycle your old one. The toxic lead and acid inside a battery can be easily replaced. Most stores refund the extra cost you pay when purchasing a new battery if you turn in your old one. 

Lead Acid Batteries vs. Absorbed Glass Mat Batteries (AGM)

Lead-Acid Battery Absorbed Glass Mat Battery (AGM)
They are cheaper than AGM batteries. AGM batteries cost almost 40% more than regular lead-acid batteries.
They are maintenance-free They are maintenance free
They do not hold charge for long. They hold charge for long.
They do not need to be topped off with water. They do not need to be topped up with water.
They cannot sustain recharging cycles and deep discharging. They are designed to support recharging cycles and deep discharging.

Car Batteries Brands

Closeup of a car battery

When purchasing a battery for your car, try to choose one from a well-known brand. The battery may be more expensive, but it will be more durable and made from high-quality materials as compared to a cheap battery. Some popular brands that manufacture car batteries include DieHard, Optima, and Odyssey.


Optima batteries are AGM batteries that are designed to survive extreme temperatures. You can take their batteries to where temperatures are freezing or where they are boiling, but the battery will hold up. Their car batteries have an excellent balance of battery life, durability, and power. 

Optima batteries are ideal for most standard cars and can even be used for larger, more rugged vehicles such as jeeps. Some popular models include the Optima YellowTop Car battery and Optima Red top.


DieHard car batteries are well-known in the industry due to their longevity. Their batteries are built to survive extreme temperature swings without a hitch. The brand also offers an exceptional four-year warranty which is a testament to the durability of its batteries. 

Some popular models from the brand include the DieHard Platinum AGM and the DieHard Gold car battery.


Odyssey car batteries are some of the most long-lasting car batteries on the market. They are designed to last longer than an average battery as it comes with a four-year warranty. These car batteries have a substantial operating temperature and a large reserve capacity rating. 

Some of their most popular models include the Odyssey Extreme car battery and the Odyssey Performance Series.

AC Delco

ACDelco batteries are some of the best batteries in the industry if you drive a Chevy, Cadillac, or GMC. They use enhanced testing, exact fitting, and precise engineering to create durable and long-lasting batteries. 

ACDelco batteries have a full frame and thicker positive plates with a cover designed to protect against self-charge. Furthermore, it also has stamped grids that increase its durability. Batteries from this brand also have an impressive warranty that allows you a long replacement and prorated period. Some popular models from the brand include the ACDelco Gold 94R AGM and the ACDelco 94RAGM Professional AGM Automotive BCI Group 94R Battery.


1. How to tell if my battery is AGM?

The best way to tell is to check the label on the battery. If it has AGM or Absorbed Glass Mat written on it, it is an AGM battery. The label could also say maintenance-free or sealed, which also means that it is an AGM battery. 

2. What should I look for when purchasing a battery?

Suppose you are in the market for a new car battery. In that case, you should keep an eye on the battery size, freshness, reserve capacity rating, and price, among other things. 

3. What is the main disadvantage of an AGM battery?

An AGM battery’s biggest disadvantage is its cost. This kind of battery costs almost 40% more than a standard battery.

4. Is a higher CCA battery better?

Yes, generally, the higher the CCA rating, the better. However, the CCA rating may or may not matter, depending on your environment. The rating is critical to check if you live in a colder region. If you live in a warmer climate, then the CCA rating does not really matter. 

5. How to tell if a car battery needs to be replaced?

If your car struggles to start, it is a clear sign that your battery has deteriorated and has now become unfit for use. Other signs include a loss of power to your car’s electronics, your battery being over five years old, and the battery warning light has come on. Old batteries also cause the start-stop function of your car to stop working. 

6. What shortens the life of a car battery?

A car battery’s life shortens considerably when it is not securely attached, vibrates, is over or under-charged, and is put into extreme temperatures. Furthermore, if it faces water loss, its electrolyte is contaminated, or there is corrosion on the terminals, it will deteriorate much faster. 


Car batteries have short lifespans if they are cheap or not properly taken care of. You must take proper care of your battery and purchase the correct one when the time comes to replace it.

There are many different brands available on the market. Still, you should first consider features such as the battery size, reserve capacity rating, price, and battery freshness. Choosing a battery from a well-known brand also gets you a warranty to replace the battery if any problem arises. Since it is the heart of a car, extra care should be taken in your selection.