A group 31 deep cycle battery is a popular marine battery with excellent starting power. RVs, cars, and other recreational vehicles also use this battery.
Whether your battery is old or you want to upgrade your electronics, your battery will eventually need replacing. When that time comes, you want to make sure you choose the best group 31 deep cycle battery for your needs.
This blog will go over all you need to know when shopping for a group 31 battery. We’ll also provide a few recommendations of our favorite batteries on the market.
AT A GLANCE: 3 BEST GROUP 31 DEEP CYCLE BATTERIES
 JITA 100Ah LiFePO4 |  VMAXSLR125 125Ah |  Odyssey 31M-PC2150 |
|
|---|---|---|---|
| Price |  | | |
| Battery Capacity | 100Ah | 125Ah | 100Ah |
| Charging Cycles At 80% Discharge | 2000 - 5000 | 600 | 400+ |
| Weight | 24.2 pounds | 75 pounds | 77.8 pounds |
| Our Recommendation | Best price for a 100Ah LiFePO4 battery | Best group 31 deep cycle battery for long running time | Best group 31 battery for both starting and cycling |
| Score | 9.5 | 9 | 9 |
What You Should Consider When Choosing A Group 31 Deep Cycle Battery
Group 31 Battery Dimensions
Group 31 batteries are huge, so you’ll need to ensure there is enough space to accommodate them on your boat or in your RV. The typical dimensions of a group 31 deep cycle battery are:
● Inches: 13 x 6.8125 x 9.4375 (L*W*H)
● Centimeters: 33 x 17.3 x 24 (L*W*H)
It is crucial to choose one that will fit snugly in the allotted space without being too cramped. Therefore, when shopping, we recommend measuring the dimensions of your current battery and comparing it to the measurements of the new one.
Ah Rating
The Ah rating (ampere-hour rating) measures how much power your battery can hold. For example, a 50 Ah battery will supply 50 amperes of power for 1 hour. A 100 Ah battery will supply 50 amperes of power for two hours, and so on.
Typically, a group 31 deep cycle battery has an Ah rating between 95 and 125 Amp-hours. If you plan on using your battery for long periods, you’ll want to choose one with a higher Ah rating.
Keep in mind that batteries with a higher Ah rating will take longer to charge fully, and the cells will be larger, impacting the dimensions and weight of the battery slightly.
So if you consider switching your lower Ah battery for a higher one, make sure that it fits in its space correctly.
Type of Battery
There are two different kinds of batteries: lead-acid and lithium. Lead-acid batteries are the most common type of battery, but lithium batteries are becoming more popular due to their lighter weight and longer lifespan.
Lithium batteries are more expensive, but they offer several advantages over lead-acid batteries.
First, they weigh much less. Lithium batteries also last up to twice as long as lead-acid batteries. They’re more resistant to deep discharge. The main drawback is their price, but they have become less expensive in recent years.
See best lithium and lead-acid batteries for sale here:
Battle Born 100Ah LiFePO4 Battery
VMAXSLR125 125 Ah Lead-acid Battery
Weight
The weight of group 31 batteries can vary dramatically. For example, lithium batteries can weigh less than 30 pounds. However, lead-acid batteries can weigh close to 80 pounds. The most common batteries (gel cell, flooded cell, and AGM) are all lead-acid batteries.
Weight is critical because a heavier battery will be more challenging to move around. For some, an 80-pound battery might not be a big deal. But if you’re constantly on the go or have limited storage space, a lighter-weight battery will be easier to manage.
Purchase the lightest battery here:
JITA 100Ah LiFePO4 Deep Cycle Battery
Best Group 31 Deep Cycle Batteries Under $500
Vmaxtanks VMAXSLR125
The VMAXSLR125 is a 12-volt 125Ah SLA (sealed lead acid) battery. It weighs 75 pounds, measures 6.8 X 12.9 X 8.7 inches, and has six cells. It is made from military-grade custom plates and typically works for wind turbines, solar panels, and other renewable energy applications.
Since it is rechargeable, the VMAXSLR125 can work repeatedly. In addition, it has a float service lifespan of 8-10 years, which means you can use it for long-term backup power. This battery can also work as an inverter battery or general backup power.
Pros
- Long lifespan, making it a good investment
- Rechargeable so that you can use it multiple times
- Made from military-grade custom plates, making it durable
- Doubles as an inverter charger for solar panels and can supply general backup power
Cons
- Fairly heavy, weighing in at 75 pounds
- Primarily for renewable energy applications
Verdict
If you are looking for a long-lasting, durable battery, the Vmaxtanks VMAXSLR125 is a good option. If you need to power renewable energy systems or need a generator, this battery is one of the best choices on the market.
VMAXSLR125 125 Ah Deep Cycle Battery
XS Power XP3000
The XS Power XP3000 is a 12-volt battery primarily used in boats and passenger cars. It is a lead-acid AGM battery with an Ah rating of 120. Therefore, it is one of the most powerful batteries on the list.
Its dimensions are 8.5 X 6.75 X 13.35 inches. This makes it slightly larger than the VMAXSLR125. It is also a little bit lighter, weighing in at 73.4 pounds.
It is spill-proof, which means that you don’t have to worry about accidents. The battery also has a vibration-resistant design, so it is ideal for use in boats and cars.
Pros
- The battery is robust, with a 120 Ah rating
- It is spill-proof, so you don’t have to worry about accidents
- Ideal for use in boats and cars
Cons
- Heavyweight
Verdict
The XS Power XP D3000 is an excellent choice if you are looking for a powerful battery used in boats and cars. It is spill proof and has a vibration-resistant design, making it excellent for both.
XS Power XP D3000
Odyssey 31M-PC2150 Dual Purpose
The Odyssey 31M-PC2150 is a 12-volt 1150 cold-cranking amp battery. This lead-acid AGM battery weighs 77.8 pounds and has an Ah rating of 100 Ah.
Its most common application is boats, but you also use it in RVs, cars, and trucks. The battery has a vibration-resistant design and extreme heat resistance, making it ideal for these applications.
Furthermore, it has the highest recharge efficiency of any battery. It is capable of a full recharge in just 4-6 hours. Recharge efficiency is essential because it determines how long the battery will last before it needs replacing.
However, this battery is also one of the most expensive on our list, at $500.
Pros
- Vibration-resistant
- Extreme heat resistance, suitable for use in RVs and cars
- 100% recharge in 4-6 hours
Cons
- Extremely costly, with a price tag of $500
Verdict
The Odyssey 31M-PC2150 is fantastic if you are looking for a durable battery used in boats, RVs, cars, and trucks. It is also one of the most efficient batteries on the market. However, keep in mind that it carries a hefty price tag.
Odyssey 31M-PC2150 Dual Purpose
Lifeline Marine AGM GPL-31T
The Lifeline Marine AGM GPL-31T is a 12-volt battery with an Ah rating of 105. It measures 12.9 X 6.75 X 9.27 inches and weighs 69 pounds, making it one of the lightest batteries.
This lead-acid AGM battery design works best in boats. People also typically buy it with a backup system. It has a vibration-resistant design and can withstand extreme temperatures,which is ideal for these applications.
The battery also has a low self-discharge rate, meaning it will hold its charge for more extended periods.
Pros
- Works in boats and is one of the best on the market for boat owners
- Vibration-resistant design can withstand extreme temperatures
- Significantly low self-discharge rate, rechargeable in under 6 hours
Cons
- Ah rating of only 105, slightly less powerful than other batteries
Verdict
The Lifeline Marine AGM GPL-31T is ideal if you are looking for a specifically optimized battery for use in boats. It is also vibration-resistant and can withstand very hot and cold temperatures. It is slightly less powerful, but a good buy nevertheless.
Lifeline Marine AGM GPL-31T
The Best Group 31 Deep Cycle Marine Lithium Battery
Battle Born LiFePO4 Deep Cycle Battery
This 31-pound lithium-ion battery is one of the newest battery technologies on the market. It outputs 12 volts and 100 amp hours, making it comparable to lead-acid batteries in terms of power.
However, this battery has a longer lifespan (up to ten times) and can be discharged and recharged more frequently than lead-acid batteries. It is also ideal for vans, boats, and trailers because it charges faster than any other battery.
The battery also has a built-in management system that protects it from overcharging, over-discharging, and overheating. It is also made from 100% renewable energy, so it is a sustainable option.
Pros
- Newest battery technologies on the market
- Longer lifespan than lead-acid batteries
- Comes from 100% renewable energy
- Up to 10-year warranty
- Provide up to 5000 charge cycles
Cons
- The most expensive ($800)
- At 100 Ah, it is less powerful
Verdict
The Battle Born LiFePO4 Deep Cycle Battery is an excellent choice if you are looking for the newest technologies. It has a longer lifespan than lead-acid batteries and can recharge more times. However, it is one of the most expensive batteries on this list.
Battle Born 100Ah LiFePO4 Battery
JITA 12V 100Ah LiFePO4 Deep Cycle Battery
This 100-amp hour battery is one of the most powerful on our list. It outputs 12 volts and weighs only 24.2 pounds. Therefore, the JITA 12V 100Ah LiFePO4 is the lightest battery on the list.
This battery comes from lithium iron phosphate, which makes it more stable than other lithium-ion batteries. Because of its composition, it is less likely to overheat or catch fire. The battery also has a longer lifespan than lead-acid batteries and can be recharged more times.
It has a power output of 100 Ah, but some options have higher and lower outputs. The battery also has a built-in management system that protects the battery from overcharging, over-discharging, and overheating.
The best thing about it, however, is how cost-effective it is. Priced at just $370, it is one of the most affordable batteries on our list. In fact, many batteries with a lower capacity come at a higher price.
Pros
- The lightest battery on the list, weighing only 24.2 pounds
- Comes from lithium iron phosphate, which makes it more stable than other lithium-ion batteries
- Longer lifespan than lead-acid batteries, providing up to 5,000 cycles for a longer running time
Cons
- Only 3-year warranty
Verdict
The JITA 12V 100Ah LiFePO4 Battery is ideal if you are looking for an affordable, lightweight, and powerful battery. It is more stable than other lithium-ion batteries and has a longer lifespan than lead-acid batteries and can be recharged more times.
JITA 12V 100Ah LiFePO4 Battery
The Bottom Line
Overall, the battery you should choose depends on your use case. For example, if you are looking for the newest battery technologies, the longest lifespan, or the most power, you should choose the Battle Born LiFePO4 Deep Cycle Battery.
Buy Battle Born battery here:
Battle Born LiFePO4 Deep Cycle Battery
However, if you are looking for an affordable and lightweight battery, the JITA 12V 100Ah LiFePO4 Battery is a great choice. On the other hand, if you prefer a lead-acid battery, we consider the Vmaxtanks VMAXSLR125 the most versatile.
JITA 12V 100Ah LiFePO4 Battery
Vmaxtanks VMAXSLR125
FAQs
How long does it take to charge a group 31 deep cycle battery?
It usually takes around eight to ten hours to charge a group 31 deep cycle battery. However, this time may vary depending on the type of charger you are using and the battery’s condition. For example, using a fast charger may only take four to six hours if you are using a fast charger.
If the battery is in good condition, it will charge faster. However, if the battery is damaged or used for a long time, it may take longer to charge.
Are all group 31 batteries the same size?
According to the BCI, Group 31 batteries are 13 x 6.8125 x 9.4375 inches, but not all group 31 batteries are technically the same. For some reason, during the manufacturing process, each battery manufacturer will have a slightly different size when compared to the standard size above, but the difference is menial.
