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How Much Do Group 24, 27, and 31 Batteries Weigh?

weight of group 24, 27 and 31 batteries

You may have heard about marine battery group size, but what does it mean, exactly? What are the differences between, say, a group 24 and a group 27 battery?

Simply put, the larger the group number, the greater the battery’s capacity will be. This also means that batteries with larger group size numbers will generally weigh more than batteries with smaller group size numbers.

Of course, weight is an important factor with anything you install on your boat. Knowing the weight of your marine batteries is crucial to knowing how well your boat will perform and how much additional weight you can add in terms of gear and passengers.

So, how much do group 24 batteries weigh? How about group 27 or group 31 batteries?

Let’s find out, shall we?

How Much Does a Group 24 Battery Weigh?

VMAX LFP24-1265 12V 65AH LiFePO4 24 Marine Lithium Battery

Group 24 batteries have many different applications, so when choosing one for your boat, be sure to choose one that is rated for marine use. Marine rating is typically denoted by the “24M” distinction.

These batteries vary in weight depending on the type of battery and the quality of materials used to make them. For example, flooded lead-acid batteries will always weigh more than lithium batteries even if they are similar in size.

That said, most group 24 marine batteries weigh between 40 and 50 pounds. Their average dimensions are roughly 10 to 12 inches long, 6 to 7 inches wide, and 8 to 10 inches tall.

Group 24 batteries generally have an amp hour rating between 70 and 85, though some can go as high as 100 amp-hours. Most group 24 batteries are 12V batteries, and most can be wired together in series to double or triple the voltage.

Group 24 batteries can be used for powering small to medium-sized trolling motors for various lengths of time depending on the amp-hour rating and the power setting on your trolling motor. For example, the battery will supply power for longer if you keep the motor at a lower speed.

Group 24 batteries are useful for other marine applications as well. You can use them to power your boat lights or other electronics, fishfinders, or simply keep them as a backup power source.

How Much Does a Group 27 Battery Weigh?

Qty 2 VMAX MR127-100, Two Group 27 12 Volt 100Ah AGM Deep Cycle Marine Batteries

Group 27 batteries also have a range of uses, so look for the “27M” distinction to make sure you’re getting a battery that is rated for marine use. Group 27 batteries are large, powerful batteries that usually have a much higher amp-hour capacity than group 24 batteries. 

In weight, these batteries typically range from 60 to 75 pounds. Group 27 batteries made of lithium weigh significantly less. Their dimensions vary from 12 to 13 inches long, 6 to 7 inches wide, and 8 to 9 inches tall. 

These batteries are rated anywhere from 65 to 110 amp-hours. Some of them are 12V batteries, while others are 24V. Either way, like the group 24 batteries above, they can also be wired together in series to double the voltage. 

Of course, the higher power ratings mean plenty of power for most trolling motors and depending on the size of your trolling motor and the power setting you use, you may be able to use the same battery to power other devices on the boat as well.

Group 27 batteries provide plenty of charging capacity for most marine uses but keep in mind that they weigh more, so they may not be appropriate for use on very small boats.

How Much Does a Group 31 Battery Weigh?

NorthStar NSB-AGM31M AGM Group 31 Marine Battery

Group 31 batteries are generally used for marine and off-grid applications. Again, look for the “31M” distinction before purchasing a group 31 battery for your boat.

Group 31 batteries are similar in size to group 27 batteries. They typically weigh 60 to 75 pounds, and their dimensions range between 12 and 13 inches long, 6 and 7 inches wide, and 9 and 10 inches tall.

These batteries are significantly more powerful than both group 24 and group 27 batteries. They typically have an amp hour rating of 95 to 125. Some are 12V batteries while others are 24V, and like other batteries they can be wired together in series if needed.

Group 31 batteries are some of the most popular and commonly chosen for marine uses. They are powerful enough to be used as starting batteries, but they are also deep-cycle batteries so they can be used for powering nearly any of your boat’s electronics.

What’s more, these batteries often supply enough power for multiple electrical systems at once. For example, you might be able to power both your fishfinder and your boat lighting for hours off a single battery.

Group 31 batteries are a good option for large trolling motors that require a lot of power, or if you need to power a smaller trolling motor on a high-speed setting for long periods.

Battery Comparison Chart

Battery BCI group sizes explained (batteries - part 5)

Let’s take a closer look at some specific batteries. This way, we can better compare the different group sizes and weights to show how group 24 batteries are generally smaller, while group 27 and 31 batteries are larger and similar in size to each other.

(All information courtesy of DC Trolling Motor.)

Battery Group Size Weight
Deka-EastPenn Flooded Lead Acid, 75 Ah Group 24 45.5 lb
Trojan Flooded Lead Acid, 100 Ah Group 24 50 lb
VMAX Tank AGM, 100 Ah Group 27 68 lb
Deka-EastPenn Flooded Lead Acid, 105 Ah Group 31 60 lb
Deka-EastPenn AGM, 105 Ah Group 31 67.5 lb
Deka-EastPenn Gel, 97.6 Ah Group 31 68.5 lb


Regardless of their group size number, marine batteries vary in weight and dimensions. The biggest factors in determining a battery’s size, other than group size classification, are the type of battery and the quality of materials used.

Hopefully, after reading this article, you’ll have a better understanding of battery group size numbers and the role they play in helping you determine the right battery for your specific marine uses.

Happy fishing!

George H.

Thursday 4th of August 2022

For those looking for ultra lightweight marine batteries, consider Lithium Ion batteries. They can be as much as 70% lighter than a traditional lead acid or AGM battery of the same size. Another plus is they provide significantly more cycles than the same size lead or AGM battery. A group 31 Li battery may provide 5000 cycles, vs. 270 for lead acid, and 350 for AGM. The biggest detractor is their cost. They are significantly more expensive than lead acid or AGM batteries. Their longer life may balance out the initial cost. While they are VERY expensive, those looking to save a lot of weight should consider them.