Selecting the Best Trolling Motor Battery [Type & Size]

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Video best deep cycle battery for trolling motor

Choosing the best batteries to power your marine accessories can be one of the most daunting experiences in boating. With so many options available it can be easy to end up confused by manufacturer recommendations, specifications, and what really matters in battery selection.

Here, we’ll outline how to select the best trolling motor batteries for your boat in easy-to-understand terms so you can get out on the water with confidence.

Marine Battery Types for Trolling Motors

The first thing you’ll notice when selecting batteries is how many options are available and what the benefits and drawbacks of each might be. The Three most common marine batteries you’ll find are Flooded Lead Acid (sometimes called wet-cell), AGM or absorbed glass mat, and Lithium Iron Phosphate (LiFePO4).

Flooded Lead-Acid

In one way or another, all batteries use a chemical reaction to create electrical energy. The oldest and most common example of this is the flooded lead-acid battery. As the name implies, lead plates are housed within this battery and are submerged in acid (sometimes called electrolyte).

These batteries are easily the most common -and least expensive- of all the battery options. They are easily found in big-box retailers and the less expensive options can readily be found for around $100 or less.

You can expect a battery like this to last a minimum of 2-3 years, which can be extended by maintaining electrolyte (acid) levels with distilled water and using a Minn Kota Precision charger’s deep equalization mode to combat sulfation.

AGM (Absorbed Glass-Mat)

In recent years the comparative cost of AGM batteries has come down quite a bit, but they will still end up costing as much as twice what a flooded lead-acid battery of the same group size will. The defining feature of AGM batteries is that they are completely sealed and instead of liquid acid, the electrolyte used in AGM batteries is “absorbed” into mats that contact the plates within. This makes them comparatively easier to transport without the risk of spills.

From a weight perspective, AGM batteries are roughly on par with flooded lead-acid options, if not slightly heavier.

AGM Batteries are commonly called “maintenance-free” batteries as their sealed nature prevents the need to maintain the acid level within them. They also tend to last slightly longer than Flooded Lead-Acid batteries if properly maintained because of the lower likelihood of falling victim to sulfation. AGM batteries, however, have the potential to be more permanently affected after being drained completely than lead-acid batteries.

Lithium Iron Phsosphate / Lithium Ion / LiFePO4

If you’ve been in the market for new trolling motor batteries recently you may have noticed some changes to what’s available in the market. Lithium Iron Phosphate (LiFePO4) marine batteries are becoming a more common option for powering trolling motors, fish finders, and other accessories. You can learn more about lithium marine battery and their advantages in our recent blog.

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Lithium marine batteries are by far the most expensive option of the three common battery types, but as more and more manufacturers introduce Lithium options the price of these battery types will continue to fall.

If you plan to keep your boat and trolling motor system long-term, Lithium could prove to be a smart investment. With some manufacturers offering up to 10-year warranties the total cost of ownership may come out to be a wash vs. re-buying flooded batteries in the same time period.

While still out of the price range of most budget-conscious anglers, Lithium boat batteries’ main advantage is a significant reduction in weight from the other battery types, which can help make your boat more nimble, get out of the hole quicker, and modestly increase top-end speed. These battery types are also known for their ability to output higher voltage levels over long periods of time and have the potential to last several years longer than traditional battery types.

Anglers may have a hard time determining the compatibility of their trolling motors and chargers with Lithium batteries, so it’s important to note that Minn Kota Trolling motors and Minn Kota Precision (PCL) chargers manufactured in 2021 or later offer a designated lithium charge profile and all previous Precision models have the ability to charge lithium batteries when set to the AGM battery type selection. Note: Some lithium batteries have specific needs for charging. We recommend contacting your battery manufacturer to verify your lithium battery is compatible with the AGM or Lithium charging profiles (available in the charger manuals).

Deep Cycle Marine Batteries

It’s important to note that no matter what battery type you choose, you’ll want to make sure you find a “deep cycle” battery. This will be clearly labeled and all it really means is that the battery was designed for using smaller amounts of energy over longer periods of time.

The alternative to a deep cycle will be a common cranking battery – these are designed to use a lot of power all at once, like when you power the starter to turn over the engine of your car. These Battery types are also commonly found in marine applications but are generally used to start outboard engines and power auxiliary accessories.

“Deep Cycle” isn’t terminology you will always find when shopping for Lithium marine batteries, but essentially all LiFePO4 batteries are designed to operate this way.

Can I use a Dual Purpose Marine Battery for my trolling motor?

Another battery type you may find during your search is a hybrid cranking/deep cycle battery commonly referred to as a “Dual Purpose” or “Dual Purpose Deep Cycle” battery. You may wonder if these battery types are suitable for use with your trolling motor, and the short answer is yes.

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[Click Here to Shop .257 Roberts Ammo]What we can do is provide a framework to understand what average conditions might look like, and whether those are reasonably viable for a shot from the average shooter to harvest a elk in the fewest number of shots possible, i.e., ethically. Let’s dive right in. In the question of “Is the .257 Roberts within the ideal range of suitable calibers for elk hunting?” our answer is: No, the .257 Roberts is UNDERKILL for elk hunting, under average conditions, from a mid-range distance, with a medium grain expanding bullet, and with correct shot placement.Let’s look at those assumptions a bit closer in the following table. Assumption Value Caliber .257 Roberts Animal Species Elk Muzzle Energy 2040 foot-pounds Animal Weight 720 lbs Shot Distance 200 yardsWhat is the average muzzle energy for a .257 Roberts? In this case, we have assumed the average muzzle energy for a .257 Roberts round is approximately 2040 foot-pounds. What is the average weight of an adult male elk? Here we have leaned conservative by taking the average weight of a male individual of the species, since females generally weigh less and require less stopping power. In this case, the average weight of an adult male elk is approximately 720 lbs. [Click Here to Shop .257 Roberts Ammo]What is the distance this species is typically hunted from? Distance, of course, plays an important role in the viability of a given caliber in elk hunting. The kinetic energy of the projectile drops dramatically the further downrange it travels primarily due to energy lost in the form of heat generated by friction against the air itself. This phenonemon is known as drag or air resistance. Thus, a caliber that is effective from 50 yards may not have enough stopping power from 200 yards. With that said, we have assumed the average hunting distance for elk to be approximately 200 yards. What about the other assumptions? We have three other primary assumptions being made here. First, the average bullet weight is encapsulated in the average muzzle energy for the .257 Roberts. The second important assumption is ‘slightly-suboptimal’ to ‘optimal’ shot placement. That is to say, we assume the elk being harvested is shot directly or nearly directly in the vitals (heart and/or lungs). The third assumption is that a projectile with appropriate terminal ballistics is being used, which for hunting usually means an expanding bullet.Various calibersA common thread you may encounter in online forums is anecdote after anecdote of large animals being brought down by small caliber bullets, or small animals surviving large caliber bullets. Of course those stories exist, and they are not disputed here. A 22LR cartridge can fell a bull elephant under the right conditions, and a newborn squirrel can survive a 50 BMG round under other specific conditions. Again, the goal of this article is simply to address the question of whether .257 Roberts is within the ideal range of suitable calibers to harvest elk - and to this question, the response again is no, the .257 Roberts is UNDERKILL for elk hunting. [Click Here to Shop .257 Roberts Ammo]This article does not serve as the final say, but simply as a starting point for beginner hunters, as well as a venue for further discussion. Please feel free to agree, disagree, and share stories from your own experience in the comments section below. Disclaimer: the information above is purely for illustrative purposes and should not be taken as permission to use a particular caliber, a statement of the legality or safety of using certain calibers, or legal advice in any way. You must read and understand your own local laws before hunting elk to know whether your caliber of choice is a legal option.Foundry Outdoors is your trusted home for buying archery, camping, fishing, hunting, shooting sports, and outdoor gear online.We offer cheap ammo and bulk ammo deals on the most popular ammo calibers. We have a variety of deals on Rifle Ammo, Handgun Ammo, Shotgun Ammo & Rimfire Ammo, as well as ammo for target practice, plinking, hunting, or shooting competitions. Our website lists special deals on 9mm Ammo, 10mm Ammo, 45-70 Ammo, 6.5 Creedmoor ammo, 300 Blackout Ammo, 10mm Ammo, 5.56 Ammo, Underwood Ammo, Buffalo Bore Ammo and more special deals on bulk ammo.We offer a 100% Authenticity Guarantee on all products sold on our website. Please email us if you have questions about any of our product listings. Leave a commentComments have to be approved before showing up Your Name * Your Email * Your Comment * Post Comment

Dual purpose batteries have both the reserve capacity to power accessories long-term as well as the cranking amperage to start outboard engines. These are a versatile battery type and as long as the amp hour rating falls within the guidelines of the below chart these batteries are a great choice for powering trolling motors or other accessories.

Important note: is that when powering a 24 or 36-volt trolling motor system, it is not recommended to use a single battery in the 24 or 36-volt series as a starting battery as it can draw current unevenly from the system and over time lead to battery damage.

What is Marine Battery Group Size or GCI Group Size?

When shopping for trolling motor batteries you will find quite a few ways batteries are identified. One of those is called group size. Though there are a wide variety of sizes, the most common you will see are 24, 27, and 31 in marine applications.

While this size nomenclature might be confusing at first, it’s merely a way to identify the actual physical size of the battery (Length x width x height) apart from its amperage or voltage rating. This is important for determining where batteries will fit in marine and automotive applications and is an industry-standard. The approximate size in inches for batteries in each of these group sizes is listed below:

Amp-Hour Rating

Ampere (Amp)-Hour rating is another consideration and method of comparing similar marine battery styles. It is the rating used to tell consumers how much amperage a battery can provide for exactly one hour. Said another way, the Amp-Hour rating is how long the battery will be able to maintain a charge while outputting a given amperage.

For a battery that has a 100 amp-hour rating, powering a trolling motor that is drawing 20 amps, the battery will last 5 hours if constantly running (100 amp hour battery / 20 amps drawn = 5 hours of run time).

A Minn Kota trolling motor will operate with any lead-acid, deep cycle marine 12-volt battery/batteries. For best results, use a deep cycle, marine battery with at least a 110-ampere hour rating, usually a Group 27 or higher. If amp hour rating is not available, select a deep cycle battery with a minimum of 180 minutes of reserve capacity.

A good starting point for judging amp hours can be found in the table above or you can learn more by checking out our Trolling Motor Battery & Wiring Install Guide.

Cranking Amp Rating

Another rating you might stumble across in search of the perfect battery is a cranking amp rating. Usually found on cranking/starting batteries for outboard engines and are less applicable to powering a trolling motor, because they focus on quick, strong burst of power to start your outboard engine vs long-lasting power for trolling motor use.

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Cranking amps can usually be found rated as either CCA (Cold Cranking Amps) or MCA (Marine Cranking Amps). The rating outlines the number of amps a battery can deliver for 30 seconds while maintaining a voltage of at least 1.2 volts per cell – or 7.2 volts total for common six cell batteries. CCA is this measurement at 0° F and MCA is measured at 32° F to simulate a more realistic marine environment.

As previously noted, this is something you will need to check with your outboard manufacturer since cranking amps are a consideration more for starting batteries than for trolling motors.

Tips for Trolling Motor Battery Selection [Summarized]

Finding the right batteries for your fishing boat can be a daunting task, but when armed with the right information it doesn’t have to be. Some additional guidelines for trolling motor power are listed below to help make sure you can supply clean, safe power to your trolling motor.

  • Battery Type and Group Size
    • Select the battery type and group size that best suits your budget, performance desires, and space limitations.
    • Do not mix battery types in 24 or 36-volt systems (i.e. Do not connect a Lead-Acid and Lithium in a series to create a 24-volt system)
  • Battery Capacity – Amp Hour Rating
    • We suggest selecting a 12-volt deep cycle marine battery with at least 110 amp hour rating. Usually Group 27 size or larger.
    • The higher the amp-hour rating, the more run time your trolling motor will receive.
    • If an amp hour rating is not available, select a deep cycle battery with a minimum of 180 minutes reserve capacity.
  • Deep Cycle Batteries
    • No matter what battery type you choose, make sure it’s a “deep cycle” battery.
    • When shopping for Lithium marine batteries, you may not see “Deep Cycle”, but essentially all LiFePO4 batteries are designed to operate this way.
  • Cranking / Starting Batteries
    • A cranking battery is not suitable for use with an electric trolling motor because they focus on quick, strong burst of power to start your outboard engine vs long-lasting power for trolling motor use.
    • We recommend that you use separate deep cycle marine batteries for your Minn Kota trolling motor.

Other Trolling Motor Battery Resources and Information

  • Trolling Motor Wiring and Battery Guide
  • Lithium Trolling Motor Batteries [Advantages & Compatibility]
  • How to Connect Trolling Motor Batteries in Series (24-volt & 36-volt Systems)
  • The Importance of Marine Battery Maintenance
  • How to Charge a Deep Cycle Battery

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