If you want to find the best dual-purpose marine battery possible, you will want to delve a little bit deeper on what makes a dual-purpose different from a starter battery and a deep cycle battery—plus, some other factors you may forget to consider (read all about it here!).

What Does Dual Purpose Mean And What Is The Best Dual Purpose Marine Battery For The Money?

Marine batteries usually are in demand for the specific advantage factors they have that carry over to different—several—functions in bodies of water whether river, sea or an entire ocean.

More often than not, these marine batteries cater to different kinds of boats that come in both small, medium or large size scales with various energy requirements.

A typical marine battery will usually be something that has these two qualities:

1. Starter or cranking function


2. Trolling function

The former relates to how fast currents of energy (in the form of amperes) can be in distribution to an engine, and one that can be in utility even if the battery is “dead.”

For that reason, these “currents” that starter-cranking focus batteries produce often go by the label of ‘cold cranks,’ referring to the ability to start up an engine even amid frigid weather.

The latter relates to how much currents can be in delivery to the trolling motor of the boat once they are in the body of water after starting, often distributing energy to lots of applications like a boat’s searchlights, radio or any other device in connection to the engine.

For this reason, these “currents” that trolling focus batterie produce often go by the label of ‘deep cycling,’ referring to the ability to cycle an engine through several sessions on the water before going low on reserves.

A battery—marine or otherwise—that has components of both usually goes by the term of “dual-purpose.”

Dual purpose batteries are not exactly the most noteworthy when it comes to the pure starter or pure trolling, but if you are particularly starting on running and operating your marine activities, this would be a great for a novice and suitable for an intermediate because of the dual function.

Here are some of the best when it comes to dual purpose marine batteries. (NOTE: these products go up to 31 in group size, so you may want to take note of that):

The Northstar AGM31M

Northstar offers their batteries in the form of advanced glass mat with pure lead technology, making their cells one of the best in terms of performance to a high standard without sacrificing high reserve cycling, ampere per hour capacity and considerably large cranking amperes, too.

Some of the “goods”:

– Reserve capacity of 220 by minutes
– Weight of about 75 pounds
– General Capacity of 80 amperes per hours
– Cold Cranks of about 1150 in amps

In terms of both reserve capacity and cold cranking performance, it is hard to find a balance like this, considering that this battery product performs excellently in both of these categories—quite heavy though.

The Optima D31M

Optima has three different batteries in three different colors (red, yellow and blue) but the Blue Top is often a popular choice for customers who want an advanced glass mat type of battery that not only performs well but has quite a high running capacity and with recharge speeds that are above average.

Some of the “goods”:

– Reserve Capacity of 155 by minutes
– General Capacity of 75 amperes per hours
– Cold Cranks of about 900 in amps
– Weight is around 60 pounds
– Considerably and competitively faster recharges than other batteries

Though perhaps not as powerful as some of the other products that offer cold cranks and more extended reserve capabilities, this product makes up for it by way of fast recharging as well as quite robust internal vibration resistance, which can reduce overall internal heat in the battery cell—greater longevity as a result.

The Odyssey 31M

Odyssey is set up as one of the better brands that deliver on what intermediates and experts want in terms of a marine battery that performs exceptionally well for the price that you have to pay—the payoff though is quite head and shoulders above the rest, and in almost all categories and factors that can be on consideration,

Some of the “goods”:

– Reserve Capacity of 205 by minutes
– General Capacity of 100 amperes per hours
– Cold Cranks of about 1150 in amps
– Weight is about 80 pounds

It is a mighty fine battery that is present here and one that will not go away in terms of delivering “the goods” with the most amount of balance that a marine battery can have as a dual purpose.

The factor is also present with a consistent report by many users; it is hard to ignore the strength of reputation this battery garners across the battery market sphere.

Without a doubt, the Odyssey 31M beats out Optima and Northstar as arguably the better (maybe even the best) dual-purpose battery you can find in the market and for the right bargaining price.

Can You Use A Deep Cycle Battery As A Starting Battery?

As a reference above, you could, but most often than not you will find that you really cannot replace a good starter battery with a battery meant for long, “deep cycling” functions.

You can, however, opt for a better choice in experimentation and investment by selecting a perfect dual-purpose battery that can get both jobs done for a fraction of the cost that it takes to buy two of each.

But, What Is The Best Deep Cycle Battery?

With the specs above in comparison, you can make the argument that because of Northstar’s pure lead technology, you have an amazing (and rising to the ranks) product that delivers considerably considerable amounts of starting function and placing longer reserves of capacities in top priority—it beats Odyssey there.

But, if you are a relative beginner and want a balance in ‘dual-purpose’ while getting more bang for your buck, Optima’s considerably high vibrational resistance to overheating and much faster recharging makes up for a lot—Odyssey and Northstar cannot assure that. (Read the best deep cycle battery for your boat).

Make no mistake: Odyssey is (arguably) the best dual-purpose marine battery brand in the market today—but other options are indeed available.

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