Article courtesy of PumpupBoats.com - Inflatable boat guides, mods, how-to articles.

Electric trolling motors run on marine Batteries. You probably knew that already, but it’s not as simple as taking any Battery from a shelf.

To make sure the battery you choose is compatible with your motor, expectations and intended usage, there are several things you need to take into consideration:

• capacity
• voltage
• weight and size
• deep cycle or cold cranking
• maintenance
• build technology

In this guide to trolling motor batteries, you’ll learn how to choose the perfect battery for your needs and find suitable battery options as well.

Let’s start!

How to pick the right trolling motor battery

Before getting into my recommendations on specific batteries, let’s run through the things you need to know before you can choose a battery for your electric trolling motor.

Deep cycle vs cold cranking. What’s the difference?

To run a trolling motor, you need to have a battery that provides a steady source of power. So called deep cycle marine batteries are designed to do just that.

Deep cycle batteries can discharge their total power capacity over a long time, nice and slow, in a steady manner.

In contrast, cold cranking batteries are designed to crank and start outboard engines by discharging a lot of power quickly. They are basically motor starting batteries similar to car batteries. By design, cold cranking batteries cannot power a trolling motor.

You can also get dual-purpose batteries, which have both technologies integrated into a single battery shell. You would only use these on larger boats, where you need to crank the engine, and also provide power to various electrical appliances onboard.

But to run an electric trolling motor, you need a deep-cycle marine battery.

Type of battery

Marine-grade batteries are made of chemicals inside the shell. There are 4 main types of batteries, you can read more about how each works here if you like.

• Flooded
• Gel
• Absorbed Glass Mat (AGM)
• Lithium

I won’t even get into flooded or gel batteries. That is old technology, which I wouldn’t use.

AGM batteries are the most popular battery types used to power trolling motors. They are dependable, require no maintenance, are spill-free, and have better shock tolerance.

Lithium batteries are an emerging trend in deep cycle marine batteries. They are much more efficient, longer lasting, and incredibly light compared to AGM batteries of the same capacity.

The only problem is that they cost 4-5x more.

If you use your trolling motor every single day, you should get a Lithium battery. If not, you will be OK with an AGM.

Amperage hour rating (Ah)

The Amp hours rating (abbreviated Ah) is a unit of measure that tells you how much electricity the battery can store.

The larger the Ah of a battery, the more electricity it can store.

Should you get a 200 Ah battery so you can troll around for 2 days at max throttle. Probably not. There is a trade-off in size, weight and price.

For most boaters using a trolling motor, the sweet spot will be a battery between 50-100 Ah.

Battery voltage: 12, 24, 36?

The trolling motor you will pair your battery with will have a voltage rating. It will be either 12V, 24V or 36V. This motor rating is what determines how much voltage output you need from your batteries.

Most batteries have an output of 12V, which is generally enough for trolling motors with 55 lbs of thrust or less.

But motors with more than 60 lbs of thrust will require 24V output from the battery that powers them. The strongest ones need 36V!

How do you get 24V battery output for such motors?

The best way is to wire two 12V batteries in series. This combines the voltage of the two 12V batteries, so that they output a total of 24V.

Need 36V? Wire another 12V battery into the series. And make sure you don’t wire them in parallel, because that just combines their battery life, without increasing their output.

Here is a video on how to wire marine batteries in series.

Just so you know, you can also buy 24V batteries, but a single 24V battery will cost double what two 12V batteries cost.

Marine battery maintenance

Good news! If you get an AGM or a Lithium battery, they do not require any special maintenance.

Of course, there are ways to extend the life of your battery through proper charging and usage, which I’ll touch on later.

What is the “marine battery group size”?

The marine battery group size is a sizing convention set by the Battery Council. The sizes simply refer to the physical size of the battery.

The battery group size is important when looking for a replacement battery, which needs to fit perfectly into the compartment it needs to be in. These are called drop-in replacement batteries.

If you have a smart battery box like the Newport Vessels Smart Power Center, the maximum size of the battery will be specified. This box can fit a battery with group size 24 & 27.

You can get more info on the most popular marine battery group sizes in this guide.

Best deep-cycle trolling motor batteries

Here are the most dependable deep-cycle marine-grade batteries to power your trolling motor. You will find the details to each battery below the summary table.

Mighty Max ML18-12

VMAX V35-857

Interstate 35

Renogy 50 Ah

VMAX MR86-50

Mighty Max 12V 55Ah

VMAX MR127

Renogy 100Ah

VMAX MR137

Frequently asked questions

There are a lot of typical questions beginner boaters have about trolling motor batteries. Here are the answers to the most common ones.

What is the difference between a marine battery and a car battery?

Car batteries are different from marine batteries that can power trolling motors. Car batteries are cranking batteries designed to start car engines. They output a lot of power over a short amount of time, and are recharged by the alternator while the engine is running. The plates inside car batteries are thinner, so they produce less power than marine batteries.

You should never use a cranking battery to power a trolling motor, as it will overheat and fail.

Marine batteries are different. When you need to use a battery on a boat to power a trolling motor, you need a deep-cycle marine battery. These types of batteries are designed to output steady power over a long period of time, which is what is needed to power a trolling motor.

You can also get dual purpose marine batteries. These have cold-cranking and deep-cycle functionality built into the same battery shell. You can use them to start an outboard engine, and to power electrical appliances on the boat if the engine is turned off.

The term “marine battery” signifies batteries developed for use on boats. You still need to know whether you need a deep cycle marine battery, a cold cranking marine battery, or a dual purpose marine battery.

Can you use a deep cycle battery to start an engine?

Yes you can, but they are not capable of producing as much power as a cranking battery. You should get a marine-grade cranking battery to start your engine.

How long do marine batteries last?

If you take care of your battery by following maintenance best practices, your battery should last 3-5 years under normal use.

Beside proper maintenance, the number of times a battery is charged also affects its longevity. AGM batteries have 300-500 charge cycles in them, while Lithium marine batteries have a lifespan of around 5000 cycles.

Proper marine battery maintenance

Paying attention to how you use and store your battery can really extend its life cycle.

Here are a few important marine battery maintenance tips.

• Secure the battery somehow, so it doesn’t bang around in rough water.
• A battery power center can help protect a battery out on the water.
• Check the battery terminal connections often, and remove any corrosion.
• After use, give your battery a full charge.
• Fast charging cycles with high voltage are to be avoided.
• Smart multi-stage chargers are the best types of chargers. They regulate the charge and current based on what the battery needs at any given charge level, they regulate temperature.
• Never store an empty battery after use without charging. Always give it a full charge after you use it.
• Avoid storing batteries for a long time. You need to charge them every 6 months if not in use. Some smart chargers can be left plugged in, and they will trickle power to the battery as needed.
• Don’t store batteries in too hot or cold environments.

Original article: Best trolling motor battery [2020 Guide]