Full Guide of Group 31 Batteries: Dimension, Features, Types

When it comes to powering heavy-duty equipment and vehicles, Group 31 batteries are often the preferred choice. These robust energy storage solutions are widely used in commercial trucks, RVs, boats, tractors, and other applications that require reliable and long-lasting power.

In this article, we will delve into the features, benefits, and key considerations associated with Group 31 batteries.

Understanding Group 31 Batteries

Group 31 batteries are part of the Battery Council International (BCI) size groupings, which establish standardized dimensions for automotive batteries. These batteries are designed to deliver high-performance power for large vehicles and equipment, making them suitable for demanding tasks and extended usage periods.

bci group battery size

Features of Group 31 Batteries

Size and Dimensions:

Group 31 batteries typically measure about 13 inches long, 6.8 inches wide, and 9.4 inches high. This larger size allows for increased capacity, providing ample electrical power to support heavy loads and prolonged usage.

Amp-Hour (Ah) Rating:

Group 31 batteries offer high Ah ratings, which refer to the amount of charge the battery can hold. Group 24 batteries typically have a capacity of 70-85 Ah (Ampere-hours) at a 20-hour rate. In contrast, Group 31 batteries offer higher capacity, usually between 95-125 Ah at a 20-hour rate. This makes them ideal for power-intensive applications or scenarios that require a longer battery life.

With higher Ah ratings, these batteries can sustain higher electrical demands for longer periods, making them ideal for applications that require consistent and uninterrupted power.

Types of Group 31 Batteries

Group 31 batteries come in various types, including Flooded Lead Acid Batteries (FLA), Absorbent Glass Mat Batteries (AGM), Gel batteries, and Lithium-ion (LiFePO₄) options. Each type offers distinct features that cater to the specific needs of users in different situations. In order to better understand these batteries, let's delve into each type and its own specific features and advantages:

1. Group 31 Flooded Lead Acid Batteries

Flooded lead acid batteries (FLA), a type of Group 31 battery, require regular maintenance, such as monitoring corrosion levels and replenishing electrolyte levels, to ensure optimal performance. Without proper maintenance, the already limited lifespan of these batteries will be further reduced. Additionally, they need to be consistently charged to prevent damage. While flooded lead acid batteries may offer short-term cost savings, they ultimately end up costing more in the long run, especially when compared to lithium batteries.

Pros

Affordable compared to other types.
Widely available.
Can handle high current demands.

Cons

Require regular maintenance such as topping up with distilled water.
Prone to spills and leaks if not handled properly.
Not completely sealed, which can lead to corrosion and electrolyte loss.

2. Group 31 AGM Batteries

Absorbent Glass Mat (AGM) batteries use a glass mat separator to hold the electrolyte, eliminating the need for maintenance and allowing them to be mounted in any position. AGM batteries are more expensive but offer higher vibration resistance and longer lifespan compared to FLA batteries. Generally, AGM batteries last up to six years.

Pros

Maintenance-free, no need for adding water or electrolyte checks.
Excellent deep cycle capabilities.
Can handle high discharge rates.
Resistant to vibration and shock.

Cons

Generally more expensive than FLA batteries.
Can be damaged if overcharged.
Slightly lower energy storage capacity compared to FLA batteries.

3. Group 31 Gel Batteries

Gel batteries use silica to transform the electrolyte into a gel-like substance. They are known for their deep cycling capabilities and excellent performance in hot temperatures. Gel batteries are more expensive than AGM batteries but have a longer lifespan.

Pros:

Excellent vibration resistance, making them suitable for off-road and marine applications.
Good deep discharge recovery.
Maintenance-free with no need for adding water or electrolyte checks.

Cons:

More expensive compared to FLA and AGM batteries.
Lower energy density compared to AGM batteries.
Sensitive to temperature extremes.

4. Group 31 Lithium Batteries

Group 31 lithium batteries are known for their wide range of features and advantages. These batteries are lightweight, have high energy density, charge quickly, and require no maintenance. They have a long lifespan of over 3,000 cycles and can operate in various temperatures, making them environmentally friendly options. Some advanced lithium batteries, like LiTime, offer even higher charge cycles of 4,000-15,000 and longer lifespans.

With a built-in battery management system (BMS), Group 31 lithium batteries are also safer. They have a low self-discharge rate, meaning they can hold their charge for extended periods of time. This makes them ideal for emergency backup power or for use in vehicles that may be parked for long periods without use.

In addition, these batteries are highly efficient and provide a steady and consistent power output throughout their lifespan. This reliability is especially important for critical systems that require uninterrupted power supply.

Group 31 lithium batteries have a compact design, which makes them easier to install and integrate into various applications. The small size and lightweight nature make them ideal for use in portable devices or in tight spaces where every inch counts.

Pros:

Longer lifespan compared to other battery types.
Lightweight and compact design.
High energy storage capacity.
Faster charging and discharging.

Cons:

Generally more expensive upfront.
Requires a specialized charger.

Suggest reading: Can I charge LiFePO₄ lithium battery with a normal charger?

Applications of Group 31 Battery

Group 31 batteries are commonly used in a variety of applications that require high amp-hour (Ah) ratings and deep cycle capabilities. Here are some common applications for Group 31 batteries:

Automotive: Group 31 batteries are often used in semi-trucks and other heavy-duty vehicles that require a reliable power source for starting and running multiple accessories.
Marine: These batteries are ideal for powering boats and other marine applications due to their deep cycle capabilities and resistance to vibration and shock.
Learn more: How to Choose the Right Marine Battery Size?
Off-Grid Systems: Group 31 batteries are commonly used in renewable energy systems, such as solar and wind power systems, to store energy for later use.
RVs and Campers: These batteries are well-suited for powering appliances, lights, and other electrical equipment in recreational vehicles (RVs) and campers.
Emergency Backup Power: Group 31 batteries can be used as backup power sources for home or office appliances during power outages or emergencies.
Industrial and Commercial Use: They are used in various industrial and commercial applications that require reliable and long-lasting power, such as forklifts, construction equipment, and backup power for critical systems.

Key Considerations for Group 31 Battery Purchase

Compatibility: Before purchasing a Group 31 battery, ensure that it is compatible with your specific vehicle or equipment. Consider factors such as terminal type, voltage requirements, and physical dimensions to ensure a proper fit and seamless integration.

Maintenance Requirements: Group 31 batteries vary in their maintenance needs. Some batteries may require periodic maintenance tasks such as electrolyte level checks or terminal cleaning. Alternatively, maintenance-free batteries are available, which eliminate the need for regular upkeep.

Brand Reputation and Warranty: When investing in a Group 31 battery, opt for reputable brands known for their quality and reliability. Consider warranties offered by different brands, as longer warranties often indicate confidence in the product's performance and durability. LiTime has been in the industry for more than 10 years, providing high-quality lithium batteries with best-budget price. Batteries from LiTime have 5-year warranty and professional technical support, a humanized return policy, quick responses within 24hrs, as well as easy-to-understand operation manuals and online services.

litime service

Best Recommended Group 31 Batteries

1. LiTime 12V 165Ah Group 31 Bluetooth Battery

The 12V 165Ah Group 31 LiFePO₄ battery is the best choice for those who need more capacity and higher power. Breaking the boundaries of traditional Group 31 batteries, the battery delivers 65% more capacity without increasing size. This innovation provides an extra 65% longer runtime for appliances, making it one of the largest capacity Group 31 batteries on the market.

The high-performance 165A BMS delivers 2112W peak power, effortlessly handling heavy loads like air conditioners, microwaves, and coffee makers. With built-in Bluetooth 5.0 technology, users can easily track the battery voltage, capacity, state of charge (SOC), and charge/discharge status in real-time.

main features of LiTime 12V 165Ah LiFePO4 Battery-bluetooth, ip65, low temp protection bms and more

2. LiTime 12V 140Ah Group 31 Deep Cycle Battery with Bluetooth

The LiTime 12V 140Ah Group 31 deep cycle lithium battery offers advanced performance and smart Bluetooth monitoring, making it a top choice for outdoor power management. Equipped with Bluetooth 5.0, it allows you to track key metrics—like remaining capacity, voltage, and cycle count—right from your phone. With 40% more capacity than the classic 100Ah lithium battery, the battery delivers even more runtime for RVs, boat trolling motors, and solar setups, ensuring reliable, long-lasting energy.

With a robust 150A BMS, the 140Ah lithium battery effortlessly powers larger appliances like coffee makers and electric griddles, providing reliable energy for all your needs. This makes it an excellent choice for RV and camper trips, ensuring that you have the power to enjoy home comforts on the road.

The advanced BMS of this battery provides 20+ protections against overcharge, over-discharge, over-current, short circuits, and high & low temperatures. It includes pre-charge functions, auto-recovery from overload protection (30 seconds), and added protection against moisture and salt spray. These functions make it also work well in harsh marine environments.

protection information of litime 12 140ah lithium battery, ip65, low temp protection bms and more

3. LiTime 12V 100Ah Group 31 Bluetooth Battery

The LiTime 100Ah deep cycle bluetooth Group 31 battery has a range of impressive features. With Bluetooth 5.0 capability, you can easily monitor your battery's status using the LiTime App, and enjoy the convenience of remote control power-off functions. The upgraded BMS offers over 20 protections and enhanced resistance to moisture, dust, and salt spray for reliable performance, making it perfect for a marine trolling motor. The Bluetooth Battery uses high-quality EV Grade-A LiFePO₄ cells, which can last for over 4000 cycles. With a powerful output of 1280W and a capacity of 1280Wh, it provides twice the energy of a standard 100Ah lead-acid battery, but it weighs only 39% of that battery. This means you get double the power in a lighter and more compact design.

the size, weight and appearance of LitTime group 31 bluetooth lithium battery

4. LiTime 12V 100Ah Group 31 Trolling Motor Battery

The Group 31 lithium trolling motor battery is designed for your boat's trolling motors. It features an enhanced battery management system (BMS) that improves its resistance against moisture, dust, and salt spray. Additionally, it includes a low-temperature cutoff functionality that reduces the risk of circuit board corrosion. The BMS also ensures low-temperature protection by stopping battery charging when the temperature falls below 0°C/32°F and resumes charging when the temperature rises above 5°C/41°F. Moreover, it can also stop discharging when the temperature drops to -20°C/-4°F.

The battery is designed to be recycled and can withstand 4000-15000 cycles, providing a service life of up to 10 years. LiFePO₄ batteries, known for their safety and stability, serve as excellent alternatives to traditional lead-acid batteries.

LiTime battery utilizes prismatic LiFePO₄ cells, which contribute to high-temperature performance, low self-discharge rates, and high power output. With a capacity of 100Ah, this battery can handle a maximum load power of 1280W and maximum energy of 1280Wh. Moreover, it supports up to 4P4S (parallel-series) configurations, allowing for the creation of a 51.2V 400Ah battery bank, offering a maximum energy of 20.48kWh and a maximum load power of 20.48kW.

5. LiTime 12V 140Ah Group 31 Dual Purpose Marine Battery

For boaters and marine enthusiasts looking for a powerful and dependable Group 31 battery, the LiTime 1000 CCA Group 31 Dual Purpose Marine Battery is an excellent choice. Designed specifically for marine environments, this battery delivers both high cranking power and deep cycling capabilities in one unit. With 1000 CCA (Cold Cranking Amps), it provides strong starting power for outboard motors even in cold conditions, while its deep cycle capacity ensures long-lasting performance for trolling motors, fish finders, and other onboard electronics.

This dual-purpose functionality means you don’t need separate batteries for starting and house loads—saving space, weight, and complexity. Built for rugged marine conditions, the battery features a durable IP67-rated casing, offering superior protection against water, dust, and salt spray. It also includes a smart BMS for enhanced safety and Bluetooth 5.0 connectivity, allowing you to monitor battery status in real time from your smartphone.

features of LiTime 12V 140Ah lithium marine dual purpose battery: ev grade-a cells, bluetooth, self-heating function, ip67 and more

Explore more Group 31 battery options at LiTime 12V batteries series!

LiTime also offers a series of Group 24 Batteries, which has the same capacity as the Group 31 model. If you're looking for a smaller battery to fit into a limited space, this option is a great choice.

FAQs about Group 31 Batteries

1. What are the dimensions of a group 31 battery?

A Group 31 battery adheres to a standard BCI (Battery Council International) case size. The typical dimensions are 13" L x 6.8" W x 9.4" H (approximately 330×173×240 mm).

Pro Tip: While these dimensions are standard, it's always a good practice to check the exact measurements of the specific battery model you choose, as slight variations can exist between manufacturers..

2. What is the difference between Group 31 and 8D battery?

The primary differences are size, weight, and capacity. An 8D battery is significantly larger and more powerful than a Group 31.

Group 31: A versatile, heavy-duty battery typically weighing 60-75 lbs with a capacity of 75-125Ah (for lead-acid). It's common in commercial trucks, RVs, and marine applications.

Group 8D: A much larger and heavier battery, often weighing over 130 lbs with a capacity of 225-260Ah. It's used for extreme, high-demand applications like large off-grid solar systems and industrial equipment.

In short, choose Group 31 for robust mobile power and Group 8D for maximum stationary capacity. For a complete breakdown, explore our Guide to Group 8D Batteries.

3. Is group 31 better than group 24?

Neither group size is inherently "better"; they are designed for different applications. The best choice depends on your specific needs for power versus size and weight.

Choose Group 31 when you need higher capacity and longer runtime for heavy-duty applications. It is ideal for running larger electronics or for extended periods without recharging.
Choose Group 24 when space and weight are primary concerns. It is a smaller, lighter battery perfect for moderate power needs in smaller boats, compact RVs, or essential backup systems.

To see a detailed side-by-side analysis, read our complete comparison: Group 24 vs. Group 31.

Conclusion

The choice of group 31 battery is no longer limited to traditional lead-acid technologies. While Flooded Lead-Acid and AGM batteries remain viable, budget-friendly options, the clear evolution is towards Lithium (LiFePO4). With their superior lifespan, significant weight reduction, and maintenance-free operation, lithium batteries represent a powerful long-term investment. They deliver more usable energy and greater efficiency in the same physical footprint.

Ultimately, the best Group 31 battery is the one that aligns with your specific needs for power, longevity, and budget. By weighing the benefits of each chemistry, you can select a dependable power source that will keep your essential equipment running strong for years to come.

Full Guide of Group 31 Batteries: Dimension, Features, Types

Understanding Group 31 Batteries