Stay Positive With Our Auto Battery Guide

While all drivers fear the dreaded blown head gasket, faulty transmission, or failing catalytic converter, these expensive automotive issues are actually pretty rare in the grand scheme of things. A driver might never encounter one of these worst-case scenarios—but there is one common malady that is hard to escape: a dead battery. Whether it’s thanks to a forgotten interior light, low temperatures, a broken alternator, or something else altogether, dealing with a dead battery is an almost inescapable part of the driving experience.

One moment, you’re rushing off to work, and the next thing you know, you’re sitting in the driveway, fruitlessly turning the key and searching “car battery replacement in Cincinnati” on your smartphone. A dead battery can be hard to escape, but familiarizing yourself with some battery basics can help a driver avoid some of the harsher outcomes. From chemistry and longevity to different battery designs, common causes of failure, and battery-specific lingo, we’ve compiled this guide to help you charge through the battery replacement process.

What Does It Do?

While many drivers think that an automotive battery is responsible for starting the engine and powering a vehicle’s electronics, that’s not technically the case. A car battery basically has one job: providing the initial burst of power needed to activate the starting motor, which, in turn, starts the engine. A vehicle’s lights, radio, and other accessories are actually powered by the alternator, which converts mechanical energy from the engine into the electrical charge needed to keep your favorite tunes blasting out of the speakers.

That’s not to say the battery isn’t an important part of the overall design—and it doesn’t actually provide accessory power when the alternator is running below its full capacity—but knowing what it does and doesn’t do can be useful when it comes to diagnosing certain automotive issues.

How Long Do They Last?

While a battery’s true lifespan depends on a number of factors, the average car battery should last anywhere between three and five years. It’s important to remember that a car battery is essentially just a very large rechargeable battery—and like any rechargeable battery, it’s only designed to last for a certain number of recharging cycles.

As a car battery begins to age, it loses the ability to hold a charge, which can lead to some real issues the next time you go to start your car, truck, or SUV. With an average price of around $120, a replacement car battery isn’t that expensive, but if you’re looking to save a little cash, there are a few tips to keep in mind…

Battery Health 101

Some common issues can necessitate battery replacement before those three to five years are up. First off, there’s a parasitic drain that comes from leaving power-hungry accessories and lights on when the vehicle isn’t in use. Long periods of inactivity can also cause a battery to lose effectiveness, which is why you should remember to take your vehicle out for a spin every few weeks.

Alternatively, you can invest in a battery maintainer/recharger. Available for as little as $20, these battery maintainers can be plugged into a standard wall socket and connected to the positive and negative terminals of a car battery. This device feeds a trickle charge to the battery, allowing it to maintain an optimal charge and ensuring a smooth, worry-free start when it’s time to take the vehicle out of hibernation.

Then, there are the issues that drivers have little control over. Whether it’s due to an accident or exposure to extreme hot or cold temperatures, a car battery could experience some structural failure that causes it to be drained of its essential electrolyte fluid. When this happens, the battery’s cells can be exposed to air, which is a big no-no when it comes to battery chemistry. There’s often little you can do when faced with such a failure aside from investing in an entirely new battery.

A glitchy or failed alternator can also impact battery health. When an alternator fails, it can cause the battery to overcharge and lead to the electrolyte solution boiling over or leaking. On the opposite end of the spectrum, an underperforming or broken alternator will force the vehicle’s entire electrical system to rely on the battery as its sole power source; this will cause the battery to drain rapidly, though an illuminated dashboard battery light might alert some attentive drivers to the issue before it’s too late. Failing to address this can cause the battery to be depleted past the point of repair, meaning drivers will have to spring for both a new alternator and a new battery.

Types of Car Batteries

Lead-Acid Battery

Lead-acid batteries, also known as flooded lead-acid or wet-cell batteries, are the most common format on the market. Notable for their affordability, capacity, and longevity, lead-acid batteries have been the industry’s go-to source of electrical power since the early 1900s.

The typical lead-acid battery is made up of six cells consisting of a lead dioxide plate and a pure lead plate. When these plates are submerged in sulfuric acid, they produce a chemical reaction that creates the 12 volts of electricity needed to get your car started. Lead-acid batteries are cheap and efficient, but they’re also heavy, sensitive to heat and cold, and start to lose some effectiveness after around 30,000 engine starts.

Enhanced Flooded Batteries

There’s also an upgraded version of the traditional lead-acid battery known as enhanced flooded batteries (EFB). While typically reserved for larger vehicles (like RVs and marine vessels), EFBs can also be used in most cars, trucks, and SUVs. EFBs are very similar to traditional lead-acid batteries, with a few important improvements, like thicker lead plates and a poly-fleece covering that extends battery life while reducing the chances of corrosion.

These batteries typically cost around twice as much as a normal lead-acid battery but are much more robust, with an average of 85,000 engine starts. This characteristic makes EFBs a great choice for vehicles that are designed with a stop-start functionality, and EFBs are also more resistant to hot and cold temperatures.

Absorbent Glass Mat

If you’re in the market for a battery that maximizes safety, longevity, and cold-weather performance, absorbent glass mat (AGM) batteries are the way to go. Developed in the ‘70s, AGM batteries represent an improvement on the standard lead-acid design. While they’re somewhat similar, AGMs are designed with fiberglass mats positioned between the lead plates; this approach allows AGMs to produce and store more energy than standard lead-acid batteries, and they’re also safer thanks to the mat’s ability to absorb sulfuric acid.

Like EFBs, AGM batteries are perfect for heavy-duty applications, but they also outshine EFBs in a few important ways. AGMs not only offer quicker charging times and higher electrical output, but they also last a lot longer, with an average lifespan of seven years. AGM batteries stand up to cold temperatures better than standard lead-acid designs, though they lag behind EFBs when it comes to heat resistance.

Lithium-Ion Batteries

Best known for powering today’s all-electric vehicles (EVs), lithium-ion batteries are also used in many hybrid electric models and are becoming an increasingly popular choice as a replacement for the typical 12-volt lead-acid battery. Instead of relying on lead ions to produce the desired chemical reaction, these batteries employ lithium ions to get the job done.

This approach allows lithium-ion batteries to recharge more efficiently than lead-acid batteries, allowing the battery to last as long as 10 to 20 years under the right conditions—and lithium-ion batteries don’t just last longer than lead-acid batteries; they’re also lighter and boast a higher energy density, though there are some downsides.

First off, there’s the cost. Lithium-ion batteries are particularly sensitive to high and low temperatures and are still significantly more expensive than some of the more common options on the market. They’re also less sustainable and harder to recycle, posting a paltry recycling rate of 5% as compared to nearly 100% for lead-acid batteries. That said, this cost could fall in the near future as the lithium-ion market expands.

How to Choose the Right Battery

There are a couple of things to consider when buying your next car battery. We’ve already discussed different battery types, but battery size, brand, age, and cold-cranking amps also play a role when it comes to finding the perfect fit. Let’s take a quick look at each of these factors and see which battery is right for your needs…

Group Size: The first step in choosing any new battery is ensuring it’ll fit into your vehicle. Batteries are separated into different group sizes depending on the make and model, but there’s no need to break out a ruler or measuring tape, as your vehicle’s battery group size can be found in the owner’s manual or on the label affixed to the battery under the acronym BCI. Short for Battery Council International (BCI), this two-digit number typically ranges from 24 to 80 and might be followed by a number.

Brand: While many automakers will suggest replacing the original battery with a specific brand, there’s usually nothing wrong with seeking out an alternative. As long as a battery meets all the specs outlined in the owner’s manual, it should do the job just as well as the recommended brand. That said, not all batteries are created equal; some budget brands might seem like an easy way to save a little money, but just be aware that overall performance could suffer.

Manufacture Date: A battery bought new off the shelf of your local auto parts store might not be as fresh as it seems. Even when it’s not putting in work under the hood of a vehicle, a battery will only last so long, which is why you should always check the date of manufacture when buying a new battery. If you’re looking to get the full three to five years of service life, experts recommend looking for a battery that was produced within the last six months.

Cranking Amps: In order to know how well a battery is going to perform in lower temperatures, there are two numbers to keep an eye on. The first is cranking amps (CA), which indicates how much power a battery can muster when trying to start a vehicle at 32 degrees Fahrenheit. If you live in an area with fairly mild winter weather, CA might be the only metric you really need to check up on, but for those who are accustomed to icy roads and frigid temperatures, cold-cranking amps are an important metric. CA usually runs the gamut from 300 to 1000.

Cold-Cranking Amps: Cold-cranking amps (CCA) are basically the same as CA, but are measured at an ambient temperature of 0 degrees Fahrenheit. Why is this so important? In short, both batteries and engines really don’t like cold temperatures. As the thermometer drops, a battery’s available starting power can decrease by as much as 75%. Meanwhile, the amount of power it takes to get the engine to turn over can jump by as much as 350%, illustrating why CCA is so important. CCA ranges from 400 to 800 with the higher number indicating improved temperature resistance.

A Few More Words About Batteries

Before we close out our car battery overview, there are just a few other things to keep in mind. First off, most automotive batteries are recyclable; in fact, auto parts stores will credit customers anywhere from $10 to $20 for turning in their old battery when switching it out for a new one. Known as a core charge, this fee can offset as much as 20% of the purchase price, providing a good incentive for doing the right thing.

While AGM and lithium-ion batteries represent an intriguing alternative to the standard design, most drivers can get by with the time-tested lead-acid formula. Also, remember that a car battery is rechargeable—and like any rechargeable battery, it needs to be treated with a little more care than your average disposable AA. If you develop some good habits and don’t make a habit of leaving your lights on, there’s no reason why a well-maintained battery shouldn’t last for countless journeys to come.