Everything That You Have Wanted To Know About Car Batteries

Everything That You Have Wanted To Know About Car Batteries

Tinkering with what's under the hood of your car is one of the most enjoyable things that you can do as a car owner. Personalizing your vehicle can be one of the most rewarding experiences. Just like other people love adapting their computers to their particular needs, others enjoy doing the same with their vehicles.

One of the most essential components of any vehicle is the right car battery. You may be wondering why the battery is so important or what it even does for your car if the engine is the reason why the wheels spin in the first place.

Car battery.

There are many types of energy at play in most cars when they are turned on, but the following are some of the most important: kinetic energy, thermal energy, and electrical energy. It is likely that you heard some (if not all) of these terms in your science courses during high school or college.

We can get more specific and discuss rotational energy and its relation to kinetics, but that's a subject for a different time. Of course, as you add more things to your vehicle, you will find that your power needs an increase. The type of energy that will be required will depend on precisely what you decide to add to your car in the first place.

For example, if you want a roll cage in your vehicle, that will raise the weight, and you may need to improve your engine’s power output so that you can maintain the same power to weight ratio. A car’s engine creates thermal energy that is then translated into rotational energy before finally ending up as kinetic energy.

Instead of getting sidetracked, however, let's remain on the topic of car batteries. Car batteries are responsible for much of the electrical energy that is present in your car's systems. While some vehicles feature KERS (kinetic energy recovery systems) to regain some electrical power, that is typically reserved for high-end cars.

Regardless of what you do, a new car battery may eventually be a necessity. Without any further delay, let’s take a look at some of the things that you should know about these automotive components.

What Is A Car Battery And Why Do Cars Need Them?

While a car battery may sound similar to the small batteries that we use to power our electronics, you will find that they are entirely different in reality. These batteries are not made out of alkaline, and they often feature a lead-acid composition, neither of which are substances that you want to be exposed to.

It is for this reason that car batteries are often classified as hazmat (hazardous materials). You should take quite a bit of care when it comes to handling your car's battery, and you should always endeavor to dispose of these products properly.

Since your battery is usually the only component responsible for feeding your vehicle’s electronics with power, a new one may be necessary if you increase the electrical load. One way to increase the needed level of electrical power in your car is by upgrading the engine, increasing the strain on the starter.

We’ll take a closer look at some of the things that are powered by batteries in your vehicle, but for now, let’s go over the car battery’s history.

History Of The Car Battery

It makes sense when you consider that the first cars did not have batteries since they did not feature any electrical systems. As you may have seen in some cartoons or other media, cars used to have cranks so that they could get started, as the electrical starter was not widely used on motor vehicles until the 1920s.

Early electric car battery.

With the implementation of the electrical starter, cars started needing a portable source of energy so that the starter could be fed with power. Of course, over time, the battery began being used to run other features. Gas lamps were replaced with electrically operated filament headlights, and much more.

Instead of a horn, vehicles before batteries made use of a bell to alert other drivers and pedestrians of their presence. The first batteries that were used on cars implemented a 6-volt standard, as that was the more convenient option at a time when batteries were not as advanced, and energy draws were not as intense.

As the automobile evolved, however, more vehicles needed more power, and the 12-volt battery was implemented as the standard for cars somewhere around 1960. This switch to better batteries was not due to the implementation of more electronics, but rather larger engines that needed more starting power.

You may be wondering how exactly car batteries have been grounded throughout history, and the story is more interesting than you would expect. Cars initially started by grounding the positive terminal to the chassis of the vehicle, but the standards were gradually switched to negative grounding over time.

What Is A Car Battery Used For?

Starting Up The Car

Of course, the main reason for batteries being present in vehicles in the first place is due to the need for an electric starter. We have reached the point where it would be impossible to go back to manually starting engines as it would be physically impossible to crank-start the larger engines of the present day.

As an engine gets larger, it will need more energy to get combustion started in the first place, and the car’s battery will have to provide more or less of it depending on the engine’s displacement. You may be wondering how an electrical starter system works in the first place, and it is quite simple.

An electrical starter is really just a heavy-duty electric motor that draws its power from your car’s battery. The motor is connected to a gear that is in turn meshed with a larger gear in the vehicle’s engine, and it essentially turns the engine fast enough to begin the self-sustaining combustion process.

Powering The Car’s Systems

Of course, as more and more cars get more in-depth electrical systems, the battery will also be used to help power them, though it will do so to a lesser extent than the car's engine. There are many different systems in modern vehicles that need electrical power to function correctly.

Car battery under the hood.

For example, if your car has a traction control system, it is possible that it is managed by the battery. Anti-lock braking systems, stability control, and much more is present in a car that makes it much easier for you to drive without having to worry about every little detail when you brake or turn.

Keep in mind that your car's battery will not often be responsible for the vast majority of the electrical systems that are operating in your vehicle. Since the engine has much higher power output, it will be easier to convert that mechanical energy to electrical energy so that you can power your systems.

Stabilizer For The Car’s Electrical Production

As we just mentioned, much of the electrical energy in your car is produced by the engine, which seems counterintuitive when you consider that there is a perfectly capable battery in your engine bay. Of course, the problem with batteries is that they can get depleted over the course of their cycle.

Most drivers won't notice that their car battery gets depleted since it typically only uses a fraction of its power to start up the vehicle. Over the course of a longer vehicle lifetime, you may end up having to replace the battery, but some drivers replace their cars before their batteries need to go.

Since the battery can be depleted, the engine is used to produce electricity since it is easier to refill with gas. What a battery does, in this case, is that it makes sure that the electricity that is produced by the engine remains stable and does not overload your vehicle's circuitry, resulting in a short.

Powering Accessories

Of course, cars also have quite a few electrical accessories that need to be powered, and there is only so much electrical energy that can be provided by your vehicle's engine. While most stock audio systems will be able to function on the power supplied by your vehicle's motor, aftermarket options will not.

It is for this reason that most people with enhanced sound systems in their vehicles either install a new deep cycle battery that they ensure they keep adequately charged or they install a second one. The latter option is more common as a dead audio battery won't make it impossible to start your car.

Of course, there are more things that you can add to your vehicle besides just a better sound system. There are provisions for DVD players, game consoles, screens, smartphone docks, and so much more that may be too much for your car's motor to keep powered on its own in addition to starting the vehicle.

Types Of Car Batteries

Starter vs deep cycle battery chart.

Starting, Lighting, And Ignition Batteries

This is by far the most common type of battery that you will come across, as it is the variety that is most often present in stock vehicles. While there may be some notable exceptions, it is relatively uncommon for cars to come included with deep cycle batteries from the dealer since most people don't know the difference.

Of course, there is nothing wrong with a starter battery except for the fact that it can’t be recharged once it has fully been discharged. The difference between a starter battery and a deep cycle battery is similar to the difference between disposable AA batteries and ones that can be recharged with a power outlet.

As you may have guessed from the name, starting, lighting, and ignition batteries are used to power the starter and the lights of your car, but they can be used for other minor tasks. You will want to avoid connecting devices that will drain more power than usual from these batteries lest they fully discharge.

Deep Cycle Batteries

As with starter batteries, saying that a battery is a deep cycle battery will not clue you in as to its composition. Instead of defining what is inside of your battery, deep cycle refers to how it operates. Like we just mentioned, a deep cycle battery is essentially an automotive battery that can be recharged.

A deep cycle battery is a better option than a starter battery if you have modified the engine of your vehicle to take more starting power. If your starter draws more power from your battery, it will discharge faster, and you don’t want to keep buying new batteries over and over again.

Of course, there are some drawbacks to deep cycle batteries. The primary issue with this kind of battery is that it doesn’t typically come equipped with cars directly out of the dealership, so you will either have to install one yourself or get your mechanic to do so.

Valve-Regulated Lead-Acid Batteries (Aka AGM)

This is the most common type of battery, though Lead-Acid batteries have seen a gradual shift towards being safer and more efficient than the batteries of the past. The AGM in the name of these batteries stands for Absorbed Glass Mat, and it is the reason why these batteries are safer.

AGM battery illustrated.

The mat in these batteries is not made out of actual glass, but rather fiberglass, and it is arranged in a grid that makes it easier for the acid in a battery to be absorbed by the mat. Since the acid gets absorbed by this mat, AGM batteries are spillproof, making them safer for both you and your car’s engine.

Lead-Acid batteries have the advantage of being a tried and proven technology, which is also one of the reasons for them being more affordable than other options. Keep in mind that you will find AGM batteries of varying quality levels, and it is recommended that you opt for the best kind.

Wet Cell Battery

A wet cell battery may sound different but it is still a form of lead-acid battery, and it is the more hazardous of the two types that we will be discussing. When compared to an AGM battery, there is no fiberglass mat for the sulphuric acid in one of these batteries to be absorbed.

Wet cell battery illustrated.

Since a wet cell battery is much less complicated than an AGM model, it will be much cheaper, but much more care will also have to be taken when handling it. If the battery is compromised in any way, it could end up leaking sulphuric acid everywhere, which is a severe hazard that will have to be contained.

While wet cell batteries aren't as safe as AGM options, they tend to offer more power for the price, which makes them an excellent choice in some industries where they are unlikely to be compromised. Wet cell batteries are used in general aviation, industry, and other heavy-duty applications.

Lithium-Ion Batteries

The Li-Ion battery is best known for being used in both cell phones and laptops, and it makes for an excellent power source when scaled down, but it has some issues when the scale goes up. It is for this reason that relatively few Li-Ion batteries have been implemented in vehicles.

The few Li-Ion batteries that have been used in cars have been used for different applications than you would imagine for a typical vehicle battery. Most vehicles with Lithium-Ion batteries are electric vehicles that use their battery as the primary power source, much like the original Tesla Roadster.

Lithium-Ion Batteries illustrated.

You may be wondering what the exact issue is with Li-Ion batteries in cars, and it all has to do with the price. Larger batteries of this type are just too expensive for use in anything but the priciest cars. The much higher price point of these batteries is not offset enough by their performance difference.

Size Of The Car Battery

Of course, you will also have to account for the size of a car battery, especially if you are looking for a new one. There are many different sizes available for car batteries, as there are different sizes of cars. Some batteries will be designed to be used as secondary batteries, and they will be much smaller.

It is essential to be sure that you are getting the right battery size, especially if you are planning on replacing an existing battery. If need be, you will want to take your vehicle to the mechanic so he can confirm your battery size. Since batteries can't be returned, you may just end up with a useless battery otherwise.

While smaller batteries can fit into larger battery compartments, you will need to ensure that you have the right amount of bracing to ensure that it doesn’t rattle around under the hood. 90% of the time, there is no feasible reason to install a battery that is smaller than what your vehicle accepts.

What Is The Average Life Time Of A Car Battery?

There are so many different factors that can change the lifespan of your car battery that it will be nearly impossible for us to provide an estimated range. Some car batteries will be able to last upwards of ten years, while others will sometimes operate for less than a single year, it all depends on the circumstances.

First off, you will have to consider what type of battery you have installed in the first place. A deep cycle battery will typically last longer than a starter battery due to the simple fact that it can be recharged in the first place. After that, you will have to consider what is drawing power from your battery.

A battery that is running your sound system in addition to starting your car will last for a much shorter time than one that is powering only your lights and ignition. In addition to all of this, you will also have to consider the weather outside, as higher humidity will end up killing your battery faster.

Testing Your Car Battery To See How Healthy It Is

There are a few different ways that you can check your battery to see its charge level. The most reliable method is by using a multimeter, which is a tool that can display an electrical system's voltage, current, and resistance. Simply connect your multimeter to your battery and check if it is outputting over 12.5 volts.

Battery multimeter in use.

If your battery's voltage is lower than the output mentioned above, it is likely running out of charge. Another way to check is to do the headlight test, in which you turn on your engine and the headlights and check to see if their brightness changes when the engine revs. If this is the case, your battery is dying.

Does Jump Starting Harm Your Battery?

Many people wonder if jump starting can damage either of the batteries involved in the process. As long as you have a car that is relatively modern with all of the electrical safety features that are necessary, jump starting someone else's car will not result in any damage to yours.

On the other hand, if you are having your car jump started, you don't have to worry about your battery being damaged any further. Many people assume that pre-existing damage was caused by a jump start, but that exact damage is likely the reason why they needed a jump start in the first place.

How To Replace Your Car Battery

  • Unscrew the nuts holding the clamps to the terminals.
  • Remove the connector clamps from the battery terminals. Start with the negative (black) clamp, and then move to the positive (red).
  • Remove the nut from the hold-down clamp and then unfasten it.
  • Take the battery out of its tray.
  • Clean out the battery tray and connector clamps thoroughly before placing a new battery into it.
  • Attach both connector clamps to your battery’s terminals, starting with positive (red), and ending with negative (black).
  • Ensure that everything is correctly fastened to the terminals before tightening the battery clamp.


We hope that this guide has given you all of the necessary information about car batteries. Feel free to move on to our buying guide in which we will take a look at some of the best car batteries on the market. Good luck finding the best car battery for your needs!

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