A Quick Guide to Choosing the Best Car Battery

If your battery goes down quickly or goes flat every morning, chances are that it needs to be replaced. The following is a definitive guide to help you get the best battery replacement that will power all electrical loads in your car for longer periods even without running the engine.

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A car battery is an important component of a car. It powers your car’s electricals and electronics and more importantly provides the power that the starter motor needs to crank your car. However, a battery does not have eternal life. In a couple of years or after several uses, the electrical energy storage device will deteriorate and eventually fail. Some batteries even fail prematurely, which is why I wrote this battery replacement guide.

Symptoms of a Dying Car Battery

Before a car battery dies completely, you may notice indicative signs such as having to bug your neighbor every morning to jumpstart your car. Sometimes or cranking the engine a couple of times before it starts. Another common symptom of a dying battery is if the car battery goes flat when you leave the headlights on shortly after turning off the motor.

Other accessories such as fog lights, interior lighting, and stereo drain a lot of charge from the battery. You can use them to tell you if you have a weak battery when you leave them on for a few minutes without running the engine.

Another way to troubleshoot a dying battery is to perform a battery load test to determine if you need to swap out the battery. Alternatively, if you happen to have a flooded battery, you can perform an electrolyte test using a hydrometer to find out which cells are bad.

Factors to Consider When Selecting a Car Battery

Once you have established that your car battery needs replacement, there are important factors you may need to consider, especially if you do not intend to replace it with the same type your car shipped with. Some times, the stock battery might not be sufficient for your power needs. As such, you may need to look beyond what the car manual recommends or go for higher rated. To help you get the most suitable battery for your car that will not fail prematurely or underserve you, I have put together this battery replacement guide for you

  1. Car Owner’s Manual

    Car Owner’ Manual Battery Specifications

    A lot of people often ignore a car owner’s manual when buying a car battery. What they don’t know is that this small booklet contains very vital information about the basic battery specifications. If you purchase a battery that does not meet the minimum criteria outlined in the car owner’s manual, the battery might not work as expected or serve you as long as it should. Therefore, it is important to refer to the car manual to know the minimum battery specifications. More importantly, you need to pay attention to the following two parameters:

    • Reserve Capacity (RC)

      Reserve capacity is an important industry rating for batteries. It is defined as the number of minutes it will take a fully charged 12-volt battery at 80° F to power a 25Amp load constantly until the voltage drops to 1.75V per cell or 10.5 volts overall. The rating states the amount of time in minutes the battery would support the alternator load without running the engine.

      You can use the RC rating of your car to know how long you should keep the headlights of your truck lighting with the engine turned off. A higher RC rating means that the battery can support the alternator load for a longer period. This means you can keep the lights and other electronic accessories on for a longer period without running the engine. For example, if your car owner’s manual suggests a reserve capacity rating of 90 mins, it means you need a battery with an equal or higher rating to power up alternator load for at least an hour and a half. Otherwise, a battery with a lower rating might not serve you as long as it should. The number of electronic loads also affect the RC. Additional auxiliary loads reduce the RC time.

    • Cold Cranking Amp (CCA)

      Cold cranking amp refers to the number of amperes that can be pulled from a battery at 0° Fahrenheits for 30 seconds while maintaining at least 7.2V. In other words, CCA is simply the battery’s ability to start the engine in cold temperatures. The CCA of a car battery should at least be equal to the value specified in the car manual. If the value is lower, you may not get a sufficient number of starts in the lifetime of the battery. Moreover, a battery with a relatively high CCA rating is the best for cold weather.

  2. Driving Pattern

    Your driving pattern may help to determine the battery specifications that will give you the best performance. For example, if you are a taxi guy doing several short distances, you may need a battery with a higher cold cranking amp rating. Such a battery would give you more cranking times within its lifespan. It would also make up for the insufficient charging time resulting from your driving pattern. If you drive for longer periods, the CCA rating might not matter as much because there is sufficient charging time. This means that most of the times when you are cranking the engine, the battery is fully charged and the CCA is high enough.

  3. Car Battery Type

    There are three main types of lead-acid car batteries. Each type has its own pros and cons.

    • Flooded cell or Wet Cell

      A flooded cell battery contains a liquid electrolyte that is free to move around in the battery housing. They are of two types: non-sealed and sealed. The sealed type, also called open-top battery, has removable vent caps that allow you to inspect and add distilled water to extend the battery life. This type of battery should be mounted upright to avoid spillage of battery acid. In terms of cost, the open-top lead-acid battery is relatively inexpensive and can serve you for a long time if maintained properly.

      On the other hand, the sealed wet cell battery, also known as valve-regulated lead-acid (VRLA) battery, does not have removable vent caps. Instead, it has small, valved-regulated holes for expelling excess gases. As such, no maintenance is needed for this type of battery hence the name “maintenance-free”. Thus, a sealed flooded car battery is ideal for people who may forget to check the level of battery water. In terms of price, this type is more expensive than the non-sealed with the advantage of not having to worry about electrolyte testing kits. Instead, all you have to care about is cleaning the terminal posts.

    • Absorbed Glass Mat (AGM)

      AGM batteries are constructed differently from the conventional flooded battery. Instead of having free moving electrolyte, AGM batteries have battery acid wrapped around the plates with fiberglass mats. The plates are tightly wrapped with the mats such that they are insulated from high temperatures and vibration. These types of batteries are more common in speciality applications where weight, power, safety, and reliability are paramount. Some of the applications include military and performance vehicles. However, that does not mean you cannot use them on your car but you have to cough more money because comparatively, they are twice as expensive as the premium wet cell batteries. Overall, AGM batteries deliver better performance than flooded batteries both in terms of CCA and RC and are more versatile.

    • Gel Cell

      Gel battery gets the name from its gellish electrolyte which is employed to reduce electrolyte evaporation and spillage. The battery is designed for resistance to extreme temperatures, shock, and vibration. Similar to the AGM, gel cell is categorized as maintenance-free and thus does not require the addition of distilled water. Despite its design for rugged conditions, a gel cell battery works best for deep discharge applications. In fact, it has a usable capacity of 75% or rather it can be deeply discharged up to 25%. For that reason, a gel battery may not be an ideal SLI (Starting, lighting, and ignition) car battery because of the poor CCA rating.

  4. Car Battery Group Size

    The battery group size determines the physical size of a car battery and the position the terminals. It is indicated on the battery with letters and numbers. You can look up the right group size for your car type and model by doing a simple search on the internet.

  5. Car Power Demand

    A lot of people install extra electronics, sound systems, and lights in their cars that lead to increased power demands. As such, it is good to perform a load analysis versus your driving pattern to determine the battery that might serve you better. For example, if you generally don’t drive for long and you have a high wattage sound system that you like to listen to when the engine is off, chances are that your battery might discharge more than it can recharge. As such, you need a battery with a higher reserve capacity rating.

  6. Battery Manufacture Date

    The date of manufacture of a car battery is specified in month and year. It is important to look at the manufacturing date to avoid purchasing a battery that has already started to deteriorate while on the shelves.Ideally, a new car battery should not be older than a few months. Personally, I prefer one that has not stayed for more than two months.

  7. Warranty of Car Battery

    Batteries are no longer cheap. Therefore, you should consider the one that offers reasonable warranty cover so that if the new battery fails within the coverage period, you can get free repair or replacement.


Hey there! I am an field electrical engineer by day, a blogger by night, and DIYer on weekends. Throughout my career, I have used many tools and learned that getting the right tool for the job is the first step to getting the job done right. This is why I write about tools and tests/reviews them on this blog.