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Group 24 vs. 27 Battery: Size does not always matter

Purchasing batteries for your automotive vehicle can be an overwhelming experience, especially when there are dozens of brands with variable group sizes available. Checking their dependability, consistency, durability, and compatibility is essential. However, does a bigger battery size means more reliability?

Not always! However, sometimes the popularity plays a crucial role in the demand and supply of a battery, making it worth your money. Currently, Group 24 and Group 27 batteries are popular among the masses. It’s due to their dimension, chemistry, types, and intended use. Therefore, today we will be scrutinizing both battery group sizes and evaluate which is better and why?

Understanding Battery Group Sizes

Before proceeding further, it’s vital to understand the concept of battery group sizes. of course, we all are aware that batteries come in numerous sizes and shapes, right? But what does “group” mean in the case of a battery?

To resolve your confusion, “group” simply refers to the ‘size’ of a battery. The Battery Council International determines the battery group sizes. It’s an international trade association promoting the lead battery industry. They are involved with battery manufacturers, retailers, marketers, and suppliers, working as specialized consultants.

So, BCI has created these specific designations to differentiate a battery based on size. Battery size will define the perfect fit based on certain things. It includes physical dimensions, terminal locations, and the type essential for your automotive vehicle. A battery group size is usually based on your vehicle’s model, makeup, and engine type.

Within sight, modern vehicles are different and have unique requirements. For example, there was a time when the vehicle had a lot of space under the hood. However, it may be true now that state-of-the-art vehicles cram more technology into a much compact space. Therefore, getting the wrong sized battery may give you the experience of fitting a square in a circle- it’s just not right!

The Difference between Group 24 and Group 27 Batteries

The BCI Group 24 batteries usually categorize as general-purpose ones, commonly found in vehicles, larger UPS systems, medical equipment, industrial applications, and security systems. In contrast, Group 27 batteries are more powerful and larger. In addition, they have higher reserve capacities and more cranking amps.; Group 24 is mainly used in deep cycle standby applications.

The following are the four main differences of BCI Group 24 and Group 27 batteries you must remember.


Group 24 batteries are categorized as medium-sized lithium and lead-acid batteries. They are generally regarded as lightweight batteries. However, this all depends on internal construction. Usually, the weight varies from 43 pounds to 46 pounds, making an easy conversion of 19.5 kg to 20.9 kg.

Contrarily, Group 27 batteries are larger and highly powerful in performance. The majority of the time, people refer to these as heavy-weight options for the vehicle. Therefore, it is better to check the space available in your automotive vehicle and make sure it can afford that size. The weight usually ranges from 54 to 70 pounds, making it much heavier than Group 24 batteries.


Whether Group 24 or Group 27 battery, you must clearly understand the battery group size because they are measured in length, width, and height in millimeters and inches.

A Group 24 battery features smaller dimensions of 260 mm in length, 173 mm in width, and 225 mm in height. The other dimensions are 8 7/8 inches in height, 6 13/16 inches in width, and 10 1/4 inches in length.

BCI Group 27 battery is bigger than its competitor. The dimensions are 306 mm in length, 173 mm in width, and 225 mm in height. In order to understand easily, Group 27 battery is 12 1/16 inches in length, 6 13/16 inches in width, and 8 7/8 inches in height. Both batteries have the same width and height; it’s the length that makes them different.

Power Rating

When discussing the power rating difference, both Group 24 and Group 27 batteries can be further evaluated in three main categories. These categories are capacity, cold cranking amp, and reserve capacity.


Since the dimensions of Group 24 batteries are slightly shorter, they feature a smaller capacity. They come with a 20h capacity (50-75 vs. 75-85 Ah), while Group 27 batteries feature a 20h capacity housing 66-110 Ah range. This is primarily due to its larger size and the capability it comes with.

An ideal Group 27 battery for energy storage applications and heavy automotive vehicles. It also charges 40% faster as compared to other contenders,

Cold Cranking Amp

Not sure what’s cold cranking amp is? CCA or Cold Cranking Amp typically measures the battery’s capability to start your vehicle in freezing weather. We all know that during extreme weather conditions, vehicles take time to start, right? That’s where the CCA of a battery comes in hand.

Sadly, Group 24 batteries are rarely considered as the best cranking amp partner. In extreme weather, you need to ignite your vehicle multiple times to start the engine. However, Group 27 batteries are considered as best pals in terms of CCA. These batteries feature 930 amps cold cranking amp rating and usually start a vehicle in the first ignition. In addition, group 27 batteries can provide exceptional results at 0°F (-18°C).

Optima BlueTop 8027-127 D27M
Optima BlueTop 8027-127 D27M
One of the best Group 27 battery. Optima BlueTop 8027-127 D27M delivers excellent performance even in extreme conditions with its unmatched CCA.

Reserve Capacity

“Standing Power” is referred to as the battery’s reserve capacity rating. It indicates how long a fully charged new battery can continue its operations. It determines the amount of time a battery can unremittingly supply the minimum voltage essential to run a vehicle.

BCI Group 24 again has a shorter reserve capacity of 100-145 vs. 140-180 minutes, which isn’t impressive compared to Group 27 results; the latter has a remarkable reserve capacity rated at 195 minutes. In simple words, it means that a fully charged battery can provide 25 amps for 195 minutes conveniently, which is fantastic.


Without any doubt, Group 24 and Group 27 batteries are pretty similar in many aspects. For instance, dimensions, capacity, and length. However, the reserve capacity and cold-cranking amps make them different at many levels.

The Battery Council International recommends not to use both of the batteries interchangeably. Why? Because they are not the same, using them simultaneously can potentially cause a bigger problem for your vehicle. However, if you are persistent, seek explicit permission from the manufacturers regarding the intent of usage of the batteries.


Batteries are the most critical, non-negotiable component of an automotive vehicle. You cannot neglect them or else be ready for a severe energy burst and damage. In worse-case scenarios, a wrong decision and negligence can be a fatal threat to your life as well.

Group 24 batteries are suitable for their intended purpose, while Group 27 batteries have their own classification. However, they are not interchangeable, and you should also not try them without consultation with the manufacturer.

Since every battery has different advantages and disadvantages, let us closely evaluate the pros and cons of both Group 24 and Group 27 batteries for a clearer picture.

Group 24

From the above information shared in this blog, we have evaluated so far that Group 24 batteries are more petite. These are superior for general purpose work and smaller vehicular capacity. But for perfect understanding, let’s scrutinize its merits and demerits.


  • Affordable
  • Easy to install
  • Sturdy design
  • Light weight


  • Short reserve capacity
  • Not ideal in colder regions

Group 27

Battery Council International’s Group 27 is a great contender so far. It has a larger capacity, is more prominent in size, and is believed to be a heavy-duty battery. Therefore, it can power larger automotive vehicles with ease. Nevertheless, a more detailed picture will clear out the things more!


  • Works exceptionally well for deep-cycle purpose
  • Superior battery capacity
  • Ideal in cold temperature
  • More reliable with high reserve capacity


  • Quite heavy
  • Bulky dimensions


Without any doubt, Group 24 and Group 27 batteries are pure models of perfection. If used as per their intended, they can produce magnificent results. For better understanding, let us dive into more details of realistic examples. These manufacturers are producing some exceptional Group 24 and Group 27 batteries. Time to check them out and help you pick up your favorite!

Group 24

We will discuss two top-rated Group 24 batteries that are popular among the masses. Their manufacturers are renowned and believed as market leaders.

Delphi BU9034R MaxStart AGM

Delphi Technologies are regarded as the premium battery producers. They offer corrosion-resistant batteries that promise to deliver formidable performance and exceptional power delivery. Their heavy-duty batteries are popular as an excellent value for money and reliable power sources.

Best Features

  • Has Cold Cranking Amps rating of 775 amps
  • Provides standard voltage rating of 12 volts
  • Backed with a 3-years warranty


  • Unbeatable for long term usage
  • Standard voltage supporting higher compatibility
  • Excellent vibration and corrosion resistance
  • More reliable with high reserve capacity


  • Capacity ratings can be quite lackluster

Check Price at Amazon


A high-end and premium battery manufacturer, promising exceptional performance throughout. NorthStar is an ideal battery for long-term use optimized functioning. In addition, they are a sustainable brand, delivering reliable power solutions to all.

Best Features

  • It comes with a battery capacity of 76 Ah
  • Provides standard voltage rating of 12 volts
  • It comes with an exceptional 4-year warranty


  • Quick cranking up in moderate weather
  • Cycles more than 900 times at 50% depth of discharge


  • Costs more than the general expectation

Check Price at Amazon

Group 27

Group 27 also features two top-class battery manufacturers leading the industry with an example.

Optima Batteries 8027-127 D27M

One of the leading Group 27 battery manufacturers famous globally, they produce high-quality batteries for heavy vehicles. Optima Batteries promises the ultimate version of a professional battery that delivers performance even in extreme conditions.

Best Features

  • 3X more recharges as compared to other Group 27 batteries
  • 15X vibration resistance and shock absorption
  • It offers a maintenance-free experience


  • Completely spill-proof
  • Cold Cranking Amps are high and powerful
  • Solid cast cell connections with superior durability


  • Can be quite expensive

Check Price at Amazon

VMAX SLR100 12V 100ah

VMAX is an ideal Group 27 battery for energy storage applications and heavy automotive vehicles. It is fascinating AGM design makes it eye-catching. Moreover, due to its exceptional and uncompromised built quality, VMAX batteries are famous worldwide.

Best Features

  • Leakproof operations
  • Heavy-duty Group 27 battery with AGM deep cycle
  • Charges 40% faster as compared to other contenders


  • Long-lasting battery with the highest number of discharge and recharge cyclesf
  • Almost maintenance-free
  • Solid shock and vibration resistant


  • Bulky dimensions
  • Warranty period is underwhelming

Check Price at Amazon

In Conclusion

Group 24 battery and Group 27 battery are both reliable and durable contenders. They are durable and offer exceptional performance. In addition, some brands of Group 24 battery offer cold-cranking amps as well, making it a good choice.

However, Group 27 batteries are a superior choice in the long run. It’s not because they are any better than Group 24 batteries. In fact, they are pretty expensive and are much larger to carry. However, Group 27 batteries are more popular among the masses as powerful batteries with reliable and durable performance.

More prominent brands are manufacturing Group 27 batteries and offering more options to choose from. Especially the shock and vibration resistant feature makes them a superb choice, ensuring a smooth traveling experience for all.

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