The 9 Best Dual-purpose Marine Batteries of 2020
As the name suggests, dual-purpose marine batteries are designed to provide 2 functions. Since they are used to power trolling motors, the 2 functions are:
- Starting the motor
- Running the motor
Starting the motor requires high amperage to crank it to life while running it requires a large capacity so that you can have enough power to propel your boat for a long time.
That said, if you are looking for a battery to help you achieve this, below is a review of 9 of the best dual-purpose marine batteries to consider buying.
What Does Group Size Mean?
Battery group size is a standard of specifications that is set by the Battery Council International (BCI) for automotive and marine battery manufacturers in North America.
These specifications include the battery’s voltage, terminal types, configuration and most importantly, its dimensions. It can be broken down into the following:
10.25 x 6.8 x 8.9
12.1 x 6.8 x 8.9
13 x 6.8 x 9.4
10.25 x 6.8 x 7.9
9.1 x 6.9 x 8.9
9.4 x 5.1 x 8.8
12.1 x 7.5 x 7.6
10.25 x 7.1 x 7.7
There are some slight variations in between such as 22NF (9.4 x 5.5 x 8.9 in) and 24F (10.75 x 6.8 x 9 in.), just to name a few. Basically, this group size is meant to show you the battery’s dimensions so that you get a fitting size for your boat.
9 Best Dual-Purpose Marine Batteries – Review
1. Vmaxtanks MR137-120 (Best Overall)
2. Vmaxtanks VMAX857 TM (Best for the Money)
3. Optima 8027-127 (Vibration Resistant)
4. Odyssey 31M-PC2150ST-M (Has Long Cycle Life)
5. Vmaxtanks MR96-1200 (Has Military-Grade Plates)
6. Optima 8052-161 (Spill-Proof Design)
7. Optima 8016-103 (Has Stainless Studs)
8. Optima 8006-006 (Maintenance-Free Design)
9. Odyssey 34M-PC1500ST-M (Has Long Shelf Life)
1. Vmaxtanks MR137-120
2. Vmaxtanks VMAX857 TM
(Best for the Money)
3. Optima 8027-127
4. Odyssey 31M-PC2150ST-M
(Has Long Cycle Life)
5. Vmaxtanks MR96-1200
(Has Military-Grade Plates)
6. Optima 8052-161
7. Optima 8016-103
(Has Stainless Studs)
8. Optima 8006-006
9. Odyssey 34M-PC1500ST-M
(Has Long Shelf Life)
1. Vmaxtanks MR137-120 – Best Overall Dual-Purpose Marine Battery
- CCA: 1740 Amps
- Reserve Capacity: 230 mins
- Capacity: 120 Ah
- Weight: 75 lbs.
- Group Size: 31
Vmaxtanks MR137-120 takes the top spot because it has a high cold cranking amperage rating of 1740 amps, which ensures you have enough power to start small or large trolling motors.
Additionally, the unit has a high capacity of 120 Ah, which means it holds enough reserves to run the motor for up to 230 minutes.
This is made possible by heavy-duty lead-tin alloy grids that give exceptional performance in terms of charge capacity. These also enhance the battery’s service life in float or cyclic use even after several recharge-discharge cycles.
That said, the unit has a float service life span of 8-10 years, which is quite long.
The battery is maintenance-free and consists of an electrolyte suspension system with AGM (Absorbed Glass Matt). This system does not include silica gels or any other contaminants.
The only problem is that the unit is very heavy (75 lbs.) but it has a carrying handle for easy transportation.
2. Vmaxtanks VMAX857 TM – Best Dual-Purpose Marine Battery for the Money
- CCA: 300 Amps
- Reserve Capacity: 75 mins
- Capacity: 35 Ah
- Weight: 25 lbs.
- Group Size: U1
If you are on a tight budget, Vmaxtanks’ VMAX857 TM is the best marine battery to buy because it is very affordable. It also has the benefit of being compact (7.7 x 5 x 6.6 in.) and lightweight (25 lbs.), which makes it ideal for small boats.
Just like the MR137-120, this one has heavy-duty lead-tin alloy grids, which enhance the battery’s performance and service life even after multiple discharge cycles.
You also get maintenance-free operation due to its electrolyte suspension system with AGM while a carrying handle makes it easy to carry.
On the downside, the battery has a low capacity of 35 Ah and a low cranking amperage of 300 amps, which is only suitable for small trolling motors.
3. Optima 8027-127 – Vibration Resistant Dual-Purpose Marine Battery
- CCA: 800 Amps
- Reserve Capacity: 140 mins
- Capacity: 66 Ah
- Weight: 53.8 lbs.
- Group Size: 27
With its spiral cell technology, Optima’s 8027-127 has a superior vibration resistant design that makes it very durable. Additionally, these cells are tightly compressed, which makes them up to 15 times more vibration resistant than traditional batteries.
The spiral cell design allows lead material to be used in its purest form. This gives it a relatively high capacity of 66 Ah, as well as a reserve capacity of 140 mins.
Apart from that, you get tightly sealed cells that are leak-proof, which allows you to mount the battery in any position. The unit also has glass-mat separators that absorb the electrolyte for acid-free, maintenance-free use.
However, the battery lacks a carrying handle despite weighing 53.8 lbs., which is quite heavy.
4. Odyssey 31M-PC2150ST-M – Dual-Purpose Marine Battery with a Long Cycle Life
- CCA: 1150 Amps
- Reserve Capacity: 205 mins
- Capacity: 100 Ah
- Weight: 77.8 lbs.
Odyssey’s 31M-PC2150ST-M is characterized by a long life-cycle, in which it is designed to last up to 70% longer than other conventional deep cycle batteries.
In actual numbers, the battery lasts up to 400 discharge cycles at 80% depth of discharge while delivering high stable voltage throughout.
Other than that, this unit has a high recharge efficiency because it can fill up to 100% in 4-6 hours. This is very fast in sealed lead battery standards.
More features include a spill-free AGM design that can be mounted in any position, a vibration-resistant design that can withstand mechanical shocks, a relatively high 1150-amp cranking power and a deep cycling capacity of 205 mins.
You also get a temperature-resistant design that can operate in temperatures between -40˚F to 176˚F. On the downside, the battery is very expensive and very heavy.
5. Vmaxtanks MR96-1200 – Dual-Purpose Marine Battery with Military-Grade Plates
- CCA: 1150 Amps
- Reserve Capacity: 120 mins
- Capacity: 60 Ah
- Weight: 43 lbs.
- Group Size: 22NF
This dual-purpose marine battery is fitted with tough military-grade plates, which are more durable than the Pb-Ca plates used in other batteries. These also enhance its performance in float or cyclic applications and maintain this performance even after multiple discharge cycles.
Other than that, the unit has a relatively high cranking power of 1150 amps, making it ideal for starting up large trolling motors.
You also get a maintenance-free electrolyte suspension system with a highly porous AGM design that absorbs the acid solution and carrying handles for easy transportation.
The only problem is that the battery is not temperature resistant, especially for low temperatures. It has an operating range of -4˚F to 140˚F.
6. Optima 8052-161 – Spill-Proof Dual-Purpose Marine Battery
- CCA: 900 Amps
- Reserve Capacity: 155 mins
- Capacity: 75 Ah
- Weight: 59.8 lbs.
- Group Size: 31
Just like the Optima 8027-127, this model has a spill-proof design that is mountable in any position and is ideal to use on boats or RVs.
Apart from that, the unit has a spiral cell design that gives it a unique structure because it looks like several cylinders put together.
This design improves its vibration resistance, making it more durable. It can withstand up to 15 times more vibrations as compared to other traditional batteries.
Other features include a cranking power of 900 amps that is constant even in bad weather, a charge capacity of 75 Ah that holds reserves for up to 155 mins and dual SAE 5/16” stainless steel studs that are rustproof.
On the downside, the battery is relatively expensive.
7. Optima 8016-103 – Dual-Purpose Marine Battery with Stainless Studs
- CCA: 750 Amps
- Reserve Capacity: 120 mins
- Capacity: 55 Ah
- Weight: 43.5 lbs.
- Group Size: 34
Optima’s 8016-103 is characterized by dual SAE 5/16” stainless steel studs that are sturdy, rustproof and very durable.
These studs churn out power from a set of spiral cells, which are highly efficient because they provide the optimal starting power of 750 amps even in cold weather. The cells are also very durable because their design makes them vibration resistant.
Apart from that, the battery is spill-proof and can be mounted in any position for maximum flexibility.
Other features include a capacity of 55 Ah with a reserve capacity of 120 mins and a maintenance-free AGM design. The only problem is that no handle is built-in for easy transportation.
8. Optima 8006-006 – Maintenance-Free Dual-Purpose Marine Battery
- CCA: 800 Amps
- Reserve Capacity: 100 mins
- Capacity: 50 Ah
- Weight: 38.4 lbs.
- Group Size: 34
This blue top marine battery is an AGM type that incorporates the use of an electrolyte suspension system, which makes it maintenance-free.
That said, the battery has a spiral design that is made up of very pure lead cells. This gives it high-performance characteristics, in which it delivers the optimal starting power of 800 amps even in cold weather.
Additionally, this design is vibration resistant for maximum durability and is housed in a sturdy seal that can withstand rough handling. The housing is completely sealed and this gives a spill-proof performance, allowing you to mount it in any position.
You also get durable rustproof stainless-steel studs but no handle is built-in for easy carrying.
9. Odyssey 34M-PC1500ST-M – Dual-Purpose Marine Battery with a Long Shelf Life
- CCA: 880 Amps
- Reserve Capacity: 135 mins
- Capacity: 68 Ah
- Weight: 49.5 lbs.
Rounding up the list is Odyssey’s 34M-PC1500ST-M and this one is built to have a long shelf life. When fully charged, it can be stored for up to 2 years on an open circuit without the need to recharge.
Other than that, the battery has a shock-resistant design that withstands mechanical vibrations. It is also temperature resistant because it can operate normally from as low as -40˚F to 176˚F.
You also get a maintenance-free AGM design that requires no water refills. It does not spill and has a resealable venting system.
More features include a high recharge efficiency, a deep cycling capability of up to 400 cycles at 80% discharge depth, a durable flame retardant cell container and tin-plated brass terminals that are corrosion resistant.
However, you don’t get a spiral cell design, which is more shock resistant.
How to Buy the Best Dual-Purpose Marine Battery
1. Type of Marine Battery
There are two main types of dual-purpose marine batteries. These are Flooded Lead Acid (FLA) and Sealed Lead Acid (SLA) batteries.
FLA batteries contain an acidic electrolyte that moves around lead plates to store charge. These are housed in a casing with openings to add on distilled water because the lead plates release hydrogen and oxygen during the charging process.
That said, they must be well vented because hydrogen is flammable and must be placed upright to prevent the electrolyte from leaking through the openings.
On the other hand, SLA batteries are very similar to the flooded type but there is no opening to access the internal components.
Because no gases are lost (no openings), maintenance is not required and therefore, the battery’s lifespan can be calculated through its discharge cycles.
Some of them do have small valves that allow the gasses to escape when charging but others have Absorbent Glass Mats (AGM), which are thin sheets of fiberglass placed between the lead plates.
These ensure the hydrogen and oxygen are recombined when charging and therefore, no venting or maintenance is required. Since they are sealed, these batteries can be mounted in any position, making them very practical. Though expensive, they are highly recommended.
2. Cold Cracking Amps
CCA can be defined as a battery’s starting power or the amperes that it can deliver in the first 30 seconds at a temperature of 0˚F.
As a general rule of thumb, the higher the CCA rating, the better and this gives Vmaxtanks’ MR137-120 and edge above the rest. This enables it to power on large motors or engines when running a big boat.
However, this has an impact on price because high ratings result in a high price. Therefore, the best thing to do is to check the starting power required by your engine/motor, then buy a battery with a slightly higher CCA rating.
A battery’s capacity is measured in ampere-hours. For instance, with its 50 Ah rating, Optima’s 8006-006 can supply 50 amps continuously for 1 hour. If your motor draws 10 amps per hour, the battery can run it for 5 hours.
The higher the capacity, the better the battery because this implies you have more charge to run your motor. That said, Vmaxtanks’ MR137-120 takes the top spot because it has a capacity of 120 Ah.
4. Reserve Capacity
While the discharge time depends on the amp draw, reserve capacity is the discharge time taken by a fully charged battery to supply 25 amps until it drops below 10.5 volts at 80˚F.
Just like capacity, the higher the reserve capacity, the better the battery. This results in longer run time and ideally, a value above 200 minutes is best. For this, check out Vmaxtanks’ MR137-120 and Odyssey’s 31M-PC2150ST-M.
Portability is determined by the battery’s size and weight. Small and compact units, such as Vmaxtanks’ VMAX857 TM, are easy to carry but on the downside, they have a small capacity.
If you are worried about this factor, ensure to get the battery that has the required capacity so that you don’t have to carry along excess baggage.
6. Battery Boxes
In marine conditions, a battery is exposed to fluctuating temperatures, rain, and saltwater splashes. To help protect it from damages and to maintain optimal performance, a battery box is required if your vessel lacks a battery compartment.
There are different types of battery boxes in the market but the most basic one should have battery leads and straps to tie it down.
7. Date of Manufacture
Even if unused, a battery that has been on the shelves for 1 or 2 years is not as effective as one that is straight from the production lines. Therefore, it is important to check the manufacture date so that you buy the newest battery.
In summary, the best dual-purpose marine battery should have a high CCA, capacity and reserve capacity. Vmaxtanks’ MR137-120 fits this description, making it the overall best. The battery also has a very long lifespan.
However, if you mostly navigate through rough sea waters, Optima’s 8027-127 is the best option to buy because it has a vibration-resistant spiral design. If you are on a tight budget though, be sure to check out the affordable Vmaxtanks’ VMAX857 TM.
- What Does Group Size Mean?
- 9 Best Dual-Purpose Marine Batteries – Review
- 1. Vmaxtanks MR137-120 – Best Overall Dual-Purpose Marine Battery
- 2. Vmaxtanks VMAX857 TM – Best Dual-Purpose Marine Battery for the Money
- 3. Optima 8027-127 – Vibration Resistant Dual-Purpose Marine Battery
- 4. Odyssey 31M-PC2150ST-M – Dual-Purpose Marine Battery with a Long Cycle Life
- 5. Vmaxtanks MR96-1200 – Dual-Purpose Marine Battery with Military-Grade Plates
- 6. Optima 8052-161 – Spill-Proof Dual-Purpose Marine Battery
- 7. Optima 8016-103 – Dual-Purpose Marine Battery with Stainless Studs
- 8. Optima 8006-006 – Maintenance-Free Dual-Purpose Marine Battery
- 9. Odyssey 34M-PC1500ST-M – Dual-Purpose Marine Battery with a Long Shelf Life
- How to Buy the Best Dual-Purpose Marine Battery