5 Best Group 31 Deep Cycle Batteries (2021 Review) - BatterySavvy.com (2023)

If you’re in need of a replacement Group 31 deep cycle battery for your vehicle, then look no further than this list to help you find the best choice for you.

Typically, Group 31 batteries are powerful devices measuring about 13 x 6.8 x 9.44 inches (as specified by the Battery Council International). They are designed for deep discharge and cycle operations and commonly used in automotive, marine, and off-the-grid settings.

5 Best Group 31 Deep Cycle Batteries (2021 Review) - BatterySavvy.com (1)


  • Best Group 31 Deep Cycle Batteries: Our Top 5 Picks
  • 1. VMAX MR137-120 AGM Sealed Marine AGM Battery
  • 2. Odyssey 31-PC2150S
  • 3. Optima D31M BlueTop Starting and Deep Cycle Battery
  • 4. Banshee Marine Battery
  • 5. Deka East Penn 8A31DTM AGM HD Battery
  • Group 31 Batteries: FAQs

Best Group 31 Deep Cycle Batteries: Our Top 5 Picks

Searching for the right replacement battery for your vehicle isn’t always easy, especially with so many brands and battery options on the market.

We’ve made things easier for you by doing all the hard work and handpicking some of the best options available. By comparing their performance, user reviews, price, and durability, we were able to select the 5 best Group 31 deep cycle batteries that could be your perfect fit.

1. VMAX MR137-120 AGM Sealed Marine AGM Battery

5 Best Group 31 Deep Cycle Batteries (2021 Review) - BatterySavvy.com (2)

  • 13"*6.8"*8.8h Heavy Duty 12V AGM DEEP CYCLE BATTERY with Float Service Life span of 8 to 10 years.
  • Electrolyte Suspension system VMAX tanks utilize an electrolyte suspension system consisting AGM (Absorbed Glass Matt) of a high porosity that totally absorb and contain the electrolyte. No silica gels or any other contaminants are used.
  • Heavy Duty Grids: VMAX heavy duty lead tin alloys provide an extra margin of performance and service life in either float or cyclic applications, even after repeated over discharges.
  • Maintenance Free Operation: There is no need to check specific gravity of the electrolyte or add water to VMAX tanks during float service life. In fact, there is no provision for this type of maintenance. Battery Cables: https://www.amazon.com/dp/B07NLJBT65?ref=myi_title_dp
  • RECOMMENDED CHARGER: VMAX BC1215 12V 15Amp 7-Stage "Smart" Charger/Maintainer (http://www.amazon.com/gp/product/B00IZV91Q0)


  • AGM design
  • Weight: 75 lbs
  • Dimensions: 12.9 x 6.8 x 8.5 inches
  • CCA: 900 A
  • HCA: 1740A
  • Capacity: 120 Ah
  • Voltage: 12 volts
  • Reserve Capacity: 230 mins
  • Made in the USA
  • Warranty: 1-year full replacement
  • Service life: 8–10 years

Our Review

If you’re looking for an affordable yet efficient Group 31 deep cycle battery that ticks all the right boxes when it comes to performance and durability, then the VMAX MR137-120 by VMAXTANKS could be just what you’re looking for.

The VMAX MR137-120 features an electrolyte suspension system consisting of a high porosity absorbent glass mat (AGM) that totally absorbs and contains the electrolytes within the battery without the use of traditional silica gels or any other contaminants. This ensures that the battery remains efficient during use, and alleviates the risk of leakage or corrosion.

Rather than the lead alloy plates we see in most batteries, this battery comes with lead-tin alloy plates that boost performance and service life. Whether you use this battery in floating or cyclic discharge applications, the plates offer optimal performance every time.

As well as a high-performance battery that will power your vehicle over long periods of time without any noticeable drop in output, with this pick, you also get a durable heavy-duty battery that boasts an impressive design. Its AGM design is incredibly durable, prevents acid spills, and keeps the battery operating effectively even after years of use.

Another impressive feature of the VMAX MR137-120 is its maintenance-free operation. Incredibly, unlike other batteries, there’s no need to add water to the VMAX’s tanks or check the gravity of the electrolytes during float service.

What we like

  • Long float service life.
  • Low self-discharge.
  • Higher power density than many competitors.
  • Does not require much maintenance.
  • Operates well in a wide range of ambient temperatures.

What we don’t like

  • Short warranty.

2. Odyssey 31-PC2150S

5 Best Group 31 Deep Cycle Batteries (2021 Review) - BatterySavvy.com (3)

  • Cold Crank Amp (CCA)- 1150; Better warranty: Limited 3 and 4 year full replacement warranty – not pro rata; Longer service life: With 3-10 years of service life, ODYSSEY batteries save time, money, and aggravation
  • Longer cycle life: 70 percentage longer cycle life compared to conventional deep cycle batteries, up to 400 cycles at 80 percentage depth of discharge- high stable voltage for longer periods of time
  • Faster recharge: The highest recharge efficiency of any sealed lead battery on the market, capable of 100 percentage recharge in 4 - 6 hours; Mounting flexibility: Non-spillable design
  • Vibration resistance- design protects against high impact shock and mechanical vibration; Extreme temperature tolerant- Operating temperatures from -40 degree Celsius (-40 degree Fahrenheit) to 45 degree Celsius (113 degree Fahrenheit).
  • This item is not for sale in Catalina Island


  • AGM design
  • Weight: 77.8 lbs
  • Dimensions: 13 x 6.8 x 9.41 inches
  • CCA: 1150 A
  • Capacity: 100 Ah
  • Voltage: 12 volts
  • Reserve Capacity: 205 mins
  • Warranty: 3-year limited and 4-year full replacement warranty
  • Service life: 3–10 years
  • Made in the USA

Our Review

The Odyssey 31-PC2150S is a heavy-duty battery that delivers massive starting power, rapid recovery, and extreme durability right out of the box. If you own a vehicle that runs a range of electronics, you’ll need a heavy-duty battery with enough power to keep all your gadgets running. The Odyssey 31-PC2150S comes with just the right specifications to meet those needs, boasting a strong starting current and good discharge and deep cycle operations that are sure to keep your vehicle running for long periods without losing steam.

The Odyssey 31-PC2150S provides at least 1150 CCA, 205 minutes RC and a minimum of 120 Ah, as well as a high, stable voltage for impressive lengths of time. In fact, testing has shown it’s capable of producing up to 400 cycles at 80 percent discharge.

The battery is constructed with pure virgin lead plates, that are designed to cover a large surface area and deliver maximum power, leaving traditional lead alloy plates trailing far behind them when it comes to performance.

What’s more, The Odyssey 31-PC2150S boasts a longer cycle life than conventional deep cycle batteries, and AGM technology that prevents acid spills, resists corrosion, offers high conductivity, and protects against the vibration and shock that can quickly wear other batteries down.

What we like

  • 3-10 year service life.
  • AGM design.
  • Protected by 4-year warranty.
  • Easy to install.

What we don’t like

  • A bit expensive compared to other offerings on the market.

3. Optima D31M BlueTop Starting and Deep Cycle Battery

5 Best Group 31 Deep Cycle Batteries (2021 Review) - BatterySavvy.com (4)

  • 12-Volt, 900 Cold Cranking Amps, Size: 12 13/16" x 6 1/2" x 9 3/8" tall, Weight: 59.8 pounds, Dual SAE & 5/16" Stainless Steel Stud Posts
  • Reserve capacity of 155 minutes for constant performance
  • Optimal starting power even in bad weather; Fifteen times more resistant to vibration for durability
  • This item is not for sale in Catalina Island
  • Special Shipping Information: This item cannot be returned and has additional shipping restrictions


  • SpiralCell design
  • Weight: 59.8 lbs
  • Dimensions: 12.8 x 6.5 x 9.4 inches
  • CCA: 990 A
  • Capacity: 75 Ah
  • Voltage: 12 volts
  • Reserve Capacity: 155 mins
  • Warranty: Limited 2-year full replacement warranty
  • Made in the USA

Our Review

The Optima D31M is a dual-purpose battery that serves as both a starting and deep cycle power source for people who need strong-starting, maintenance-free power for their vehicle. The battery is packed with reserve capacity, guaranteeing a longer shelf-life to give you power for as long as you need it. The battery also boasts more efficient power delivery and faster recharge time than the competition, so you’re always ready to go as soon as possible.

Like all Optima batteries, the Optima D31M features a SpiralCell design that offers more control, critical tolerance, and prevents acid spills. The SpiralCell design also ensures that the battery is safe to use and durable enough to last far longer than many of its competitors.

An advantage the Optima D31M has over conventional batteries is its low self-discharge rate. This means that the battery will still hold a charge even after long periods of inactivity, making it suitable for a range of vehicles; including motor vehicles, boats, and RVs.

What we like

  • SpiralCell design ensures elimination of acid spills.
  • Low self-discharge rate.
  • Fast recharge time.
  • Maintenance-free.

What we don’t like

  • A bit too pricey for what it is.

4. Banshee Marine Battery

5 Best Group 31 Deep Cycle Batteries (2021 Review) - BatterySavvy.com (5)

  • BATTERY TYPE: BCI 31M AGM rechargeable deep cycle marine battery with [+ -] terminals
  • Group 31M Battery | 12V 105AH AGM Gel Sealed Battery | 700CCA | Dimensions: L= 13.00" W= 6.76" H= 8.26" | Leak free, sealed design prevents corrosion. Maintenance Free. No need to add acid. | 2 Year Warranty
  • Fits and Replaces: Optima 8052-161 D31M, XMC-31, GL100, GPL-31T, GPL-3100T, ELT-AGM31, NSB-AGM31, 31M-PC2150, and More.
  • 100% Compatible OEM replacement for Personal Watercraft, Boat, Marine, RV, and More.
  • It's Not a Battery, It's a Banshee.


  • AGM design
  • Weight: 59.8 lbs
  • Dimensions: 13 x 6.7. x 9.04 inches
  • CCA: 900 A
  • Capacity: 105 Ah
  • Voltage: 12 volts
  • Reserve Capacity: 190 mins
  • Warranty: 2 years

Our Review

Featuring an AGM design and dual terminal, the Banshee Marine Battery by Banshee is the perfect heavy-duty power source for firing up your vehicle reliably even on cold winter mornings.

If the electrical needs of your vehicle are higher than average or the required discharge cycle exceeds that of typical engine starting, you’ll need a rugged battery that can get the job done. This battery might just answer your prayers, having been designed with high reserve capacity, an impressive amp-hour capacity, and an amazing CCA to meet all your power needs.

In fact, the battery boasts twice as much power as traditional offerings due to covering more plate surface area, thus generating more power.

Banshee takes safety and durability just as seriously as performance and the Banshee Marine Battery is the perfect example of that. The leak-proof AGM design ensures that the battery is as safe for use as possible, and durable enough that you won’t have to worry about needing a replacement for a long time, even with heavy use. Impressive, right?

What we like

  • Very affordable.
  • High reserve capacity.
  • Sustains charge even after long periods of inactivity.
  • Maintenance-free.

What we don’t like

  • Nothing, really.

5. Deka East Penn 8A31DTM AGM HD Battery


  • AGM design
  • Weight: 69 lbs
  • Dimensions: 12.94 x 6.75 x 9.38 inches
  • CCA: 800 A
  • Capacity: 105 Ah
  • Voltage: 12 volts
  • Reserve Capacity: 210 mins
  • Warranty: 1-year free replacement
  • Made in the USA

Our Review

The Deka East Penn 8A31DTM by East Penn is the ideal solution for heavy marine power needs, supplying renewable energy powered equipment, and powering a range of other types of electric vehicles. The battery provides ample power to start and keep your engine running for long periods of time without any noticeable dips in performance, as well as to supply multiple electronic accessories with ease

Like others on our list, the Deka East Penn 8A31DTM makes use of AGM technology, giving you a completely sealed, maintenance-free battery. The AGM design eliminates the possibility of acid leaks and the potential need for clean-up, as well as providing the battery with more power than conventional offerings around the same price point in the Group 31 market.

For many users, recharging the battery after use can be restrictive, especially if the battery charges slowly and they’re always on the move. Luckily, East Penn understands this, and has designed the Deka 8A31DTM with a fast charge capacity, as well as ensuring the battery has a fantastically low self-discharge rate of under 2% per month, meaning it will hold a decent charge even after weeks of inactivity. The disappointment of a dead battery on your next RV getaway is sure to be a thing of the past.

What we like

  • Very affordable.
  • Sealed construction prevents potentially hazardous spills.
  • High reserve capacity.
  • Slow self-discharge.
  • Maintenance-free.
  • Fast recharge.

What we don’t like

  • Short warranty.

Group 31 Batteries: FAQs

What are Group 31 batteries?

Group 31 batteries belong to the standard commercial battery commonly used in automotive, marine, industrial applications. They’re widely popular because they are able to deliver an unmatched performance even when they are pushed to their limits.

Their physical dimensions are as follows – 13 x 6.8 x 9.44inches but their features vary depending on intended use, battery design and chemistry. Generally speaking, these batteries will range between 100Ah and 125Ah, 600 CCA and 1150 CCA, and 150 RC and 230RC.

Another reason Group 31 batteries are a favorite in the automotive industry is that they are capable of delivering high current and deep cycles. They can also withstand intense vibrations and harsh temperatures with low self-discharge.

So when you’re looking for a reliable battery for your vehicle, consider opting for any of the Group 31 batteries on this list as they are able to meet the demands of your vehicle.

Are all Group 31 batteries the same size?

Although all Group 31 batteries follow the standard set by the Battery Council International, their sizes may vary a little as this depends on the manufacturer. However, the sizes do not affect the capabilities of the battery. All you need to do is to make sure that the battery model you’re considering is the perfect fit for your vehicle.

What is the difference between Group 24 and Group 31 batteries?

You’ve probably heard that Group 24 and Group 31 batteries are a great choice for those looking for a deep cycling automotive cell and this is correct as both batteries are very powerful. However, many end up thinking that they’re completely one and the same but this is not true.

Even though both categories of batteries can get the job done, Group 31 batteries produce more amp hours than Group 24 batteries. Also, the size of the former is also larger than that of the latter.


How long will a group 31 deep cycle battery last? ›

Most deep cycle batteries can last up to six years with proper care and charging (depending on the frequency of use). It's up to you to make sure that your battery isn't being damaged by your charging routine.

How many volts should a group 31 battery have? ›

Almost, the Firefly G-31 resting voltage is expected to be at 12.8V or sometimes higher. (12.9-13V) but this may take a day or two. What is the Firefly's G-31 lowest voltage the battery can withstand? 10.5V is fully discharged, 11.7V is @ 60-70% discharged.

Which deep cycle batteries last the longest? ›

When it comes to measuring how long a deep cycle battery will last the correct way is in cycles rather than time. A lead acid battery can give 200 cycles (based on 100% DOD, to 80% capacity) whereas a deep cycle lithium battery can achieve over 10 times the amount at 2000 + cycles.

What is the most efficient battery on the market? ›

Lithium-sulfur batteries are believed to be more efficient than lithium-ion batteries, which could increase the range and storage capacity of electric vehicles. Additionally, sulfur is affordable and abundant, which could mean lower cost.

What is the best battery for a boat? ›

The most versatile type for marine use is the AGM battery. If you don't use your vessel daily, AGMs will hold their charge better than wet and gel cell batteries. Long lifespan and low self-discharge rate make AGM excellent dual-purpose (deep cycle and engine starting) batteries for boats.

What is the difference between a marine battery and a marine deep cycle battery? ›

Deep Cycle Marine battery Design Features

One key difference is the battery plate: It has fewer, thicker plates allowing the battery to provide continuous power output over long time periods. Deep cycle batteries can be entirely drained and recharged many times over, where as cranking batteries can't.

Is there a difference between deep cycle and marine deep cycle battery? ›

Internally, the two batteries may be identical, but that doesn't mean the marine battery is necessarily designed, intended or warrantied for deep-cycle use. It may only be designed for starting a boat engine, not running live wells, trolling motors or large stereo systems when the engine is turned off.

Are all Group 31 batteries the same? ›

Are There Different Group 31 Battery Types? ​ Group 31 batteries can come in a variety of different battery construction types. While most Group 31 batteries are lead-acid based, they break down into different product types based on how they are constructed.

How many amps does a group 31 battery have? ›

Generally, these batteries will range between a 100-amp hour (Ah) and 125Ah, 600 cold cranking amps (CCA) and 1150 CCA, and 150 reserve capacity (RC) and 230 RC.

What is the life expectancy of a deep cycle battery? ›

How long do deep cycle batteries last? The average lifespan of a deep cycle battery is about 3-6 years. However, the lifespan of a deep cycle battery will vary based on several factors such as the type of battery, how it is used and maintained, and the climate in which it is kept.

Are AGM deep cycle batteries worth the money? ›

An AGM battery will cost more than a regular lead-acid battery — but it'll last longer and save you money in the long run. They last longer than regular batteries. Because they don't have any liquid inside them, AGM batteries have fewer components to fail, so they last longer than traditional car batteries.

How do I choose a deep cycle battery? ›

What To Look For In A Deep Cycle Battery
  1. Weight & Size. Weight and size are important considerations if you intend to use your deep cycle battery on a watercraft or RV, where you'll need to run several different electronic applications for extended periods of time. ...
  2. Charging. ...
  3. Life Span & Reliability.
Sep 28, 2015

Are AGM batteries better than deep cycle batteries? ›

Absorbent glass mats or AGM batteries have replaced the traditional deep cycle or lead acid batteries. Compared to the deep cycle battery, the AGM battery is more dependable and has better construction. The lead plates and fiberglass matting are tightly packed, making the battery shock and vibration resistant.


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