The Ultimate Guide to Car Batteries: 8 Things You Need to Know

Are you tired of being stranded on the side of the road with a dead car battery? Look no further! Our comprehensive guide to car batteries has got you covered with everything you need to know about types, maintenance, and troubleshooting.

Car batteries are essential to a vehicle, powering electronics and accessories and starting the engine. With an average lifespan of 3-5 years, knowing how to maintain and replace them is vital.

guide to car batteries

In this article, we’ll cover everything you should know about car batteries, from selecting the right one to maintaining and replacing one.

Types of Car Batteries

There are two types of car batteries:

  1. lead-acid
  2. advanced glass mat (AGM) batteries

Lead-acid batteries are the most common and affordable, while AGM batteries are more expensive but offer superior performance and longer lifespans.

AGM batteries use a different technology than lead-acid batteries, where the electrolyte is absorbed in a mat instead of being free-flowing. This results in better performance, especially in cold weather, and they are less prone to leaking and damage.

AGM batteries are also more durable and can handle deep discharges better than lead-acid batteries.

Choosing the Right Car Battery

It is essential to choose the right battery for your vehicle. The battery should fit the size and voltage requirements of your car, and you should consider the climate and driving conditions in your area.

Most car batteries have a four- or five-digit date code on the cover, indicating the manufacturer’s month and year. You can use this information to determine the age of the battery and make an informed decision on whether to replace it or not.

Battery Size Groups

Car battery sizes are standardized by the Battery Council International (BCI), which assigns each battery a group size designation that specifies the battery’s physical dimensions in inches and millimeters.

The group size designation typically consists of two digits, which may be followed by a letter, and is used to identify the battery size that fits a specific vehicle make and model.

For example, size 24F is a common battery size that fits many Honda, Toyota, Nissan, and Acura vehicles.

Other common car battery group sizes include:

  • Size 75: most General Motors cars
  • Size 65: large-bodied Ford, Lincoln, and Mercury cars
  • Size 35: recent Honda, Nissan, and Toyota cars
  • Size 34: most Chrysler cars
  • Size 34/78: some Chrysler and General Motors cars

The dimensions listed for each battery group size represent the battery’s maximum outside dimensions to the widest point, including terminal posts and flanges, as provided by the BCI Battery Replacement Data Book. Hold-down flanges at the bottom of a battery are not included in these measurements.

Choosing the right battery size and type for your vehicle is important to ensure proper battery replacement. Buying and installing an incorrectly sized battery may not only be a waste of money but may also cause damage to your car.

Testing Your Car Battery

Regularly testing your car battery using a multimeter is crucial to ensure it is in good condition. Typically, a healthy battery will have a voltage reading of around 12.6 volts when the engine is off.

If the voltage reading falls below 12.4 volts, it could be a sign of a weak battery that may need to be replaced. This simple test can help you identify potential issues with your battery before they lead to more serious problems while on the road.

You can also perform a load test to determine the battery’s ability to hold a charge. This involves applying a load to the battery for 15 seconds and measuring the voltage drop. If the voltage drops below 9.6 volts, it may be time to replace the battery.

Maintaining Your Car Battery

There are a lot of factors that affects car battery life such as hot climate. Maintaining your car battery is crucial to extend its lifespan and ensuring it performs optimally. Here are some tips for maintaining your car battery:

  • Keep the battery clean and dry, and remove any corrosion on the terminals.
  • Check the battery’s fluid levels regularly and top up with distilled water if necessary.
  • Avoid leaving your car unused for extended periods, as this can lead to a dead battery.
  • Use a battery charger or maintainer to keep the battery charged when not in use.

The Risks of Ignoring Battery Maintenance

We have encountered countless car owners who neglect battery maintenance, leading to various problems. The most common reason for this is the misconception that car batteries are maintenance-free. This couldn’t be further from the truth.

Regular battery maintenance is crucial to ensure the proper functioning of your car’s electrical system. Neglecting battery maintenance can lead to problems such as difficulty starting the engine, stalling while driving, and even complete battery failure. 

In our experience, these problems are most commonly caused by a buildup of corrosion on the battery terminals or a weak battery that needs to be replaced. To avoid these problems, it’s important to regularly check your battery’s voltage, clean the battery terminals, and replace your battery when necessary.

Symptoms of a Bad Battery

Car batteries are essential for your vehicle’s proper functioning, but they can also be a source of headaches when they go bad. Here is a list of common car problems that can be caused by a bad battery and how to identify them.

  1. Failure to start: A car battery that has gone bad will prevent your vehicle from starting. If you turn the key and hear a clicking or no sound, the battery is likely dead or dying.
  2. Dimming headlights: Dim headlights are another telltale sign of a bad battery. If you notice that your headlights are not as bright as usual, the problem may be a result of a dying battery.
  3. Slow cranking: When you turn the key to start your car and the engine cranks, but it is taking longer than usual to start, this could indicate that the battery is starting to go bad.
  4. Corrosion: Corrosion is a common issue that can cause a bad connection between the battery and the terminals. Over time, a layer of green, dusty substance appears on the terminals due to chemical reactions.
  5. Warning signs: Warning signs, such as battery saver dashboard lights or unusual noises, can indicate that your battery may be on its last legs. If you notice warning signs like these, it is best to get your battery checked by a professional.
  6. Short-circuited cells: If a separator between the positive and negative plates in your battery fails, it can cause a short-circuited cell. Another cause of short-circuited cells is a buildup of shed plate material below the plates.
  7. Sulfation: Sulfation is another issue that can occur after a long period of disuse in a low- or no-charge state. This occurs when the sulfuric acid in the battery reacts with the lead plates, forming lead sulfate on the plates.

Replacing Your Car Battery

When it’s time to replace your car battery, selecting the right one and following the correct installation procedures is important. Here are some of the tools that you will need:

  1. Gloves – to protect your hands from battery acid
  2. Safety glasses – to protect your eyes from any debris
  3. Wrench or pliers – to loosen and remove the battery terminal connectors
  4. Battery terminal cleaner or wire brush – to clean the terminals before installation
  5. Battery hold-down bracket or strap – to secure the new battery in place
  6. Battery post cleaner – to clean the battery posts before installation
  7. Battery charger or maintainer – to keep the new battery charged and maintained over time.

After selecting the right battery for your car and gathering the necessary tools, it’s time to replace the old one. Here is a DIY guide to replace car battery:

  1. First, turn off the engine and remove the key from the ignition.
  2. Then, locate the battery in the engine compartment and disconnect the negative terminal first, followed by the positive terminal. This is important to prevent any accidental electrical discharge that may cause damage to your car’s electrical system.
  3. Next, remove any brackets or fasteners that are holding the battery in place. 
  4. Carefully lift the battery out of the tray and place it aside. Ensure to avoid tilting or dropping the battery, as this can cause acid spills or damage to the casing.
  5. Before installing the new battery, clean the battery tray and terminal connectors with a wire brush and baking soda solution. This will ensure good electrical contact and prevent corrosion.
  6. Place the new battery into the tray, making sure it is level and secure.
  7. Reconnect the positive terminal first, followed by the negative terminal, and tighten the bolts securely. Make sure to follow the correct order of connecting the terminals.
  8. Finally, start the engine and check that all electrical systems are functioning properly. 

If you encounter any issues, double-check the connections and make sure the battery is securely in place. With these steps, you can successfully replace your car battery and ensure optimal performance and reliability.

Here’s a video from O’Reilly Auto Parts to help you replace car battery on your own:


In this article, we’ve covered everything you need to know about car batteries, including their types and maintenance tips. By now, you should know how to choose the right battery for your car and how to keep it in good condition.

Remember, neglecting battery maintenance can lead to serious problems, so be sure to pay attention to any signs of a bad battery like dimming headlights, slow cranking, or failure to start. Keep your battery healthy, and your car will run smoothly!

If you need help with how to take care of your car battery or need a professional to inspect and replace it, feel free to consult an expert.

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