Best Trolling Motor Battery (2021 Reviews Guide)

These days our boats have several powered accessories, which is why it’s crucial to choose the best trolling motor battery for your preferred use. Trolling motor batteries are particularly important for boaters want to make precise maneuvers on their vessels. Why? Because to achieve precise slow movements of your boat, you use a trolling motor.

What is critical to know is that a trolling motor needs its own deep cycle battery, separate from your boat’s starter motor. Or for small vessels a high-quality dual purpose marine battery.

Since there are many marine batteries on the market, I decided to help you pinpoint a few of the best. In this article, read concise reviews about 9 of the best 12v trolling motor batteries in 2021. After this, I include a handy guide about what to look for in a trolling motor battery. If you want to navigate to specific review or section there is a clickable table of contents.

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We updated this article in January 2021 to ensure the reviewed trolling motor batteries meet current standards. For this year, we introduce a one new model from the Lifeline brand. Read on to discover which best trolling motor battery in 2021 is perfect for your vessel.

Andy Sharp
January 3, 2021

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Trolling Battery Comparison Chart

Group 27 Batteries

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Group 27 Batteries

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The Best Group 27 Deep-Cycle Battery

Photo of Black VMAX MR-127 Deep Cycle Marine Battery

VMAX MR-127 Group 27

Group 27 Deep Cycle Marine Battery
Amp Hours (AH): 100
Reserve Capacity (RC): 200 minutes
Dimensions (inch): (L)12.1 X (W)6.7 X (H)8.2 /8.46 (including terminal posts)
Weight (lbs): 68
Pulse (3-second) Hot Cranking Amps (PHCA): 1580
Cold Cranking Amps (CCA): 800
Cycle life of 600 at 75% D.O.D
-20°C (-4°F) to 60°C (140ºF) Temperature Operating Range
Terminals: 8mm stainless steel postitive & negative thread stud terminals

What We Like

What We Do Not Like

Review of the VMAX MR-127:

For 2021, the VMAX MR-127 is the best trolling motor battery for motors with 25 to 45 pounds (20.41 kg) of thrust. This is a rugged and dependable Group 27, 12v deep-cycle battery. It has excellent installation flexibility, as it mounts in many positions. Plus, it can fit into any Group 27 battery box, including the Minn Kota Trolling Motor Power Center.

It’s ideal to have at least 100 amp hours if you use trolling motors with over 25 pounds (11.34 kg) of thrust. With 100Ah and a massive reserve capacity of 200 minutes the VMAX Mr-127 will meet and exceed most boaters needs.

Three Important Advantages of a VMAX Deep Cycle Battery:

First advantage is, it’s built with a rugged industrial grade plastic container. This container is a sealed non-spill battery, that’s maintenance free and durable. In fact, boaters will rarely need to worry about harsh climates or vibration damage. For easy handling, it has built-in carrying handles that flip up and down as needed.

Next in second, it has a robust inner design with lead-tin alloy plates that withstand tough deep-cycling. Surrounding the plates is AGM technology that suspends the electrolyte. As a result, this battery gives top deep cycle performance with long battery life.

The third advantage of the VMAX MR-127 is its charging speed. It charges a two times faster than similar group 27 batteries. For boaters that use the trolling motors, quick recharges are a definite bonus.

Three Caveats:

The first downside of this battery is the weight, it isn’t one you will want to move around a lot.

Second, it’s a bit pricier than other brands of group 27 marine batteries. But what would you rather use, a high quality deep cycle battery or some cheap pretender? I will justify the cost for top performance and durability.

In third, like most AGM batteries, buyers will need to factor in the cost of a proper smart charger. Which means one more item for buyers to research.

Verdict:

This is an excellent everyday use deep cycle battery for a trolling motor between 25 and 45 pound thrust. While heavier than its competition, it’s “pound for pound” the champion of group 27 deep cycle batteries. In addition, it has a decent one-year warranty for good measure.

USA Military Spec Deep-Cycle Trolling Battery

Lifeline GPL-27T Deep Cycle Battery

Group 27 Deep Cycle Marine Battery
Amp Hours (AH): 100
Reserve Capacity (RC): 186 minutes
Dimensions (inch): (L)13.09 X (W)6.60 X (H)8.13 /9.25 (including terminal posts)
Weight (lbs): 62
Marine Cranking Amps (CCA): 845
1-year warranty
Marine Terminal (Copper Alloy) Positive: M10, Negative: M8

What We Like

What We Do Not Like

Lifeline GPL-27T Review:

The Lifeline GPL-27T is a group 27 100 AH, 12v deep-cycle that’s handmade in the USA. Lifeline has an impressive pedigree as a wing of the Concorde Battery Corporation. Concorde is a pioneer of aerospace spec AGM batteries. Today they supply AGM batteries for the US Air Forces’ F-117A Stealth Bomber and F/A- 18 fighter jet.

I like the Lifeline because of the internal design. Which uses rectangular cells, instead of round cells found in competitors. Using a rectangle shape it can use all the volume inside their length, width and height. Inside are lead-calcium negative plates and lead-tin-calcium alloy positive plates. With premium absorbed glass mats compressed against every surface of the plates. Resulting in a 90% internal absorption – extending battery life and shock resistance.

Another innovative design is the use of polyethylene envelopes over the glass mats. No other manufacturer adds this level of protection inside their trolling motor battery. This micro-porous envelope wraps around the glass mat to seal and prevent sharp edges. Doing this helps to stop short circuits occurring between plates inside the battery. Short circuits are a common source of failure in marine batteries.

Industry Leading Performance

Lifeline boasts the industry leading 2% per month self-discharge rate at 77 F (25 C). Through my research I read that boaters have seen around a full charge after a whole winter of storage!

With great performance, they also excel in safety due to their innovative container. As a result this battery has no sulfuric acid leaks, no acid clean up and excellent durability. In addition, each individual internal cell uses a re-sealing pressure relief safety valve.

Disadvantages For The Lifeline Deep Cycle Battery:

For downsides, you will need to be conservative during recharging. Like many others, overcharging can damage this battery. Lifeline does suggest putting a charger on the battery after every single use. They also recommend ensuring batteries have a full charge before storing a boat. This will extend battery life but may be overkill in some boater’s opinions.

Another negative is, you cannot install this battery in a sealed container. It needs open space for the pressure relief safety valves.

Finally, some boaters don’t like the high initial cost for a Lifeline battery. But, governments and companies choose Lifeline as standard equipment on many prestigious vessels. Such as many U.S. Navy crafts, Coast Guard vessels and luxury yachts. In the end, most boaters know you get what you pay for.

Verdict:

We can all agree that any boating product approved by the US military is a great choice. Buy the Lifeline GPL-27T if you want a USA made military spec, heavy-duty, deep-cycle battery. Doing so, provides a leak proof durable power source for your vessel.

Budget Friendly Group 27 Trolling Motor Battery

Universal UB121000

Group 27 Deep Cycle Marine Battery
Amp Hours (AH): 100
Reserve Capacity (RC): 195 minutes
Dimensions (inch): (L)12.06 X (W)6.61 X (H)8.30 (9.16 including terminals)
Weight (lbs): 63.9
SLA/AGM maintenance free, spill proof battery
Internal Resistance (fully charged): 5m ohms
Mount in any position, resists shocks and vibration
Dual Stainless Steel Posts (0.86 inches in height)
Warranty: 1 year

What We Like

What We Do Not Like

Universal UB121000 Review:

This is a group 27, 12v deep cycle boat battery that is a cheap and reliable choice for a boater on a budget. The UB121000 is a good 12v marine battery from the Universal Power Group. Since 1968, this company has been constructing various power products. Including VRLA AGM & Gel batteries, chargers, security components, and low voltage wiring products.

For trolling motors, the UB121000 is a decent performer as a dedicated AGM deep cycle battery. While some boaters prefer brands like Mighty Max for inexpensive batteries, the Universal performs better at a slightly higher price. Being a deep cycle battery it should deliver stable and consistent power for a long time. Whereas cheap dual-purpose batteries, won’t be able to due to its combined uses.

Features of the Universal Trolling Motor Battery

With a rating of 100 amp hours (AH), this battery meets the standard to be a dependable choice for power hungry motors. In fact, it will deliver more than enough power to run a small to mid-sized trolling motor. Plus with the sealed AGM design, it’s spill proof and maintenance free. Another bonus of this trolling motor battery is it has a low self discharge rate of less than 3 percent per month. As a result, you can store the battery unused and without worrying about it.

Boaters will like that they can install these batteries in any position. Likewise, don’t worry about crashing over waves as its shock and vibration resistant. While it does weigh in at around sixty-four pounds, it is lighter than other group 27 options. Plus it comes with built in handles for easy handling.

Caveats & Suggested Improvements

There are some caveats to this battery though. First is that it takes over ten hours to charge the UB121000 at 10 amps. Another annoyance I found was that the terminal posts are a bit short at a little over 3/4 of an inch. If you want to connect more than two terminals or have thick connectors you may run out of threads.

In second, the shipping packaging of this battery could use improvements. Buyers have complained of damage and dead batteries, due to the lack of cushioning in the shipping box.

Third, the warranty is short at one-year, although for the price any warranty is better than nothing.

Verdict:

Choose the Universal UB121000 if you are searching for a sturdy and cheap group 27, 12v trolling motor battery. I rated it higher than Might Max marine batteries for a tad bit more money. Choosing it gets you dependable power for your small to mid size trolling motors at a great price.

The Best Group 31 Dual-Purpose Battery

Odyssey 31M PC2150ST-M

Made in the USA
Group 31 Dual Purpose Marine Battery
Amp Hours (AH): 100
Reserve Capacity (RC): 205 minutes
Dimensions (inch): (L)13 x (W)6.8 x (H)9.41
Weight (lbs): 77.8
Pulse (5-second) Hot Cranking Amps (PHCA): 2150
Cold Cranking Amps (CCA): 1150
Cycle life @ 77° F 400 at 100% D.O.D
-40ºC (-40ºF) to 80ºC (176ºF) Temperature Range
Terminals: brass SAE posts 3/8 inch positive, 5/16 negative thread SS stud terminals

What We Like

What We Do Not Like

Odyssey 31M Trolling Thunder Review:

In many instances it’s best to buy one battery to provide enormous cranking power and another battery to provide deep cycle reserve power. In general, I recommend this method, except when it comes to Odyssey.

The Odyssey 31M PC2150ST-M “Trolling Thunder” is a beast of a battery, and it’s a dual-purpose type. In fact, this 12v dual-purpose battery has the specs to beat out all the other group 31 deep cycle batteries.

What makes it the best you ask? It’s Odysseys’ innovative battery construction. First, the Odyssey 31M uses 99.99% pure lead for its plates, unlike others which use lead-tin alloys. By using pure lead, the plates can be thinner, which means more plates can fit inside.

Second, unlike spiral-plate designed batteries equal in size, Odysseys flat plates packs 15% more surface. By avoiding spiral designs there is no dead space, as a result, this battery delivers more power and reserve capacity.

Who is Odyssey Batteries?

Odyssey has some admirable roots, as their parent company Enersys, supplies pure lead AGM batteries for powering US military tanks. All their batteries are a handmade in the USA with an excellent warranty. Some people scoff at the price tag of this battery, but no other dual-purpose AGM can boast better specs.

One thing to keep in mind, this isn’t a lightweight battery, it is a hardcore trolling battery for medium/large applications. If you need a deep cycle battery for a kayak/small vessel take a peak at either the Vmaxtanks Vmax MR127-100 or Universal UB121000.

Dual Purpose Trolling Motor Battery

Do you worry about the usual compromise that happens with dual-purpose batteries? Don’t. The PC2150ST-M provides a huge engine-cranking pulse rating of more than 2250 amps for 5 seconds. This rating is triple compared to equal sized conventional batteries. Plus, for deep cycles, it will recover after 400 charge/discharge cycles to 80% depth of discharge. Plus you don’t need to worry about low temperatures. Since it can operate from – 40 °C (-40 °F) to 80ºC (176ºF) for models with a metal jacket.

Odyssey states a lifespan of 3 to 10 years. But many heavy power users have claimed a life expectancy of closer to 8 to 12 years!

If you appreciate safety and less maintenance, rest assured Odyssey has you covered. The tough container features a self-regulating gas valve to allow for gas re-absorption. Another bonus, it is flame and spill proof with a robust internal dry cell design. This design protects the internal cells against high impact shock and mechanical vibration. In addition, Odyssey uses tin plated brass for external terminals to fight surface corrosion. Surface corrosion is a common symptom of early failure.

Verdict:

Are you are searching for an amazing do-it-all trolling motor battery in 2021? Pick this one, there is no better choice than the Odyssey 31M PC2150ST-M Trolling Thunder.

Excellent For Trolling Motors Above 55lbs Thrust

NorthStar NSB-AGM31M

Made in USA
Group 31 Deep Cycle Marine Battery
Amp Hours (AH): 103
Reserve Capacity (RC): 220 minutes
Dimensions (inch): (L)12.91 X (W)6.77 X (H)9.25
Weight (lbs): 75
Pulse (3-second) Hot Cranking Amps (PHCA): 2150
Cold Cranking Amps (CCA): 1150
Marine Cranking Amps (MCA): 1370
Cycle life of 900 at 50% D.O.D
Dual Marine SAE Threaded Posts

What We Like

What We Do Not Like

Northstar NSB-AGM31 Review:

The Northstar NSB-AGM31 is an excellent trolling motor battery for motors with 55 lbs of thrust or more. NorthStar marine 12v batteries aren’t as popular as others, but they are more than capable.

In the year 2000 a group of battery engineers created the NorthStar Battery Company. At the start the company made power solutions for the telecom industry. Next, after the success in telecom, NorthStar moved on to became leaders in the automotive market. Finally, they entered the marine battery market with little-to-no fanfare. These engineers with combined 100 plus years of experience and produce great batteries.

Best Deep Cycle Battery You Haven’t Heard Of

Am I crazy to choose an “unknown” battery as a contender for best trolling motor battery? Nope, I know it’s important to realize that there are awesome alternatives to Ener-Sys and Odyssey. Like Ener-Sys, NorthStar uses 99.997% pure lead inside their batteries. Unlike the former, they compress the lead into a reinforced ABS plastic shell. Doing this aids in increasing long term power density and prevents vibration damage.

Consider a side-by-side AGM battery comparison between the Odyssey 2150 and this battery. Most ratings between the two match, except for two that are higher for NorthStar. These are the Amp Hour (AH) rating and Reserve Capacity (RC), both are higher for NorthStar.

A big bonus is that this battery is a pure deep-cycle marine battery. While the Odyssey 2150 is a great option for most trolling motors, it is in fact a dual-purpose battery. What is the caveat of a dual-purpose battery? It will never offer equal the power a pure deep-cycling battery can.

Heavy-duty trolling motors need their own power source as they sip a lot of power for long periods. Buying this NorthStar will get you a battery with superior cycle life, one that cycles over 900 times at 50% depth of discharge. That is speedy to recharge and has maintenance free operation.

Any Disadvantages?

Two main disadvantages spring to mind for the NorthStar NSB-AGM31M battery. The first is its weight, this isn’t a portable battery, keep this in mind as you plan the installation. Second, is that because it is an AGM battery it will need a smart charger which adds to the cost.

Verdict:

If your boat and by association your trolling motor is your pride and joy, don’t choose an inferior battery. With the NorthStar NSB-AGM31M expect “the power to exceed” with a tried and true deep cycle battery.

Highest Reserve Capacity (RC) Group 31 Deep Cycle Battery

VMAXTANKS VMAX MR137 Group 31

Group 31 Deep Cycle Marine Battery
Amp Hours (AH): 120
Reserve Capacity (RC): 230 minutes
Dimensions (inch): (L)12.9 X (W)6.8 X (H)8.5 /8.7 (including terminal posts)
Weight (lbs): 75
Pulse (5-second) Hot Cranking Amps (PHCA): 1740
Cold Cranking Amps (CCA): 900
Cycle life of 600 at 75% D.O.D
-20°C (-4°F) to 60°C (140ºF) Temperature Operating Range
Terminals: 8mm stainless steel postitive & negative thread stud terminals

What We Like

What We Do Not Like

VMAX MR-137 Review:

The VMAX MR-137 is a superb top pick for any boater who needs heavy-duty power at a reasonable price. I like that it has massive reserve capacity at 230 minutes and high amp hours of 120ah. This 12v deep-cycle is a great performer for Newport vessels, Sevylor, and Cobra brand trolling motors.

Besides, it is an AGM battery, which means you can mount it in any position except upside down. As for design, the manufacturer boasts of a battery built to military grade standards. With thick lead tin alloy plates and a unique chemical cell refinement process. VMAX ensures increased battery life and enhanced vibration resistance for these marine batteries.

High Performance Reliability

Another positive point for the 12v MR-137 is its low internal resistance providing maximum power density and deep cycling capabilities. As a sealed spill proof battery, you don’t need to worry about dangerous fumes or gases. It is maintenance free, you can set it and forget it, except for recharging. As for recharging, it is quick and maintains 600 cycles at 75% D.O.D.

Negatives of the VMAX MR-137:

On a negative note, some claim this battery is heavy at 75 pounds (34.02 kg). Keep in mind, the heavier a battery, the more power it can provide. Unless you plan to move the battery a lot, the weight shouldn’t be a deterrent.

The second negative to consider is that you have to be careful not to overcharge this battery. Third, it’s heavy-duty for medium/large boats, if you have a small boat or small trolling motor this isn’t battery to choose.

Verdict:

Choose this 12v battery if you need a heavy-duty deep-cycle specific group 31 battery for your trolling motor. Buyers receive the massive 230-minute RC rating, excellent durability, all at a reasonable price.

Most Affordable Group 34 Deep Cycle Battery

Banshee 34M Marine Battery

Built-in Hydrometer
Group 34 Dual Purpose Marine Battery
Amp Hours (AH): 66
Reserve Capacity (RC): 100 minutes
Dimensions (inch): (L)10.2 x (W)6.9 x (H)7.9
Weight (lbs): 37
Cold Cranking Amps (CCA): 750
Cycle life @ 77° F 400 at 80% D.O.D
Terminals: Dual post and threaded terminals

What We Like

What We Do Not Like

Banshee 34M Review:

The Banshee 34M is a deep-cycle battery that is a perfect fit and direct replacement for Optima D34M. It has excellent recharge capabilities for long-lasting performance. Due to its inner construction known as enhanced flooded battery.

What Is An “Enhanced” Flooded Battery (EFB)?

In a nutshell, EFB stands for Enhanced Flooded Battery. It is an improved version of a Wet cell battery. The improvement consists of extra carbon additives for the internal battery plates.

2 Key Features Of EFB:

Inside are two main internal characteristics that make it different to a Wet cell. One is a scrim and the second is an acid “circulator” device.

A Scrim is a polyester element added between the plate and the separator. Its purpose is to prevent the erosion of mass by holding the reactive material in its place. This results in a superior charge acceptance and an enhanced deep cyclic resistance.

The acid circulator device prevents the stratification of the acid. What it does is use the slight movements of the vessel to maintain a constant circulation of the acid.

Inexpensive & Rugged

Consider this type of battery to be the mid-tier between a Wet Cell and an AGM battery. It’s cheaper than an AGM and has better vibration resistance than a Wet cell. Unlike the Optima BlueTop’s spiral design, the Banshee uses a flat plate design. This equates to 15% more power due to less dead space between the plates.

I love that an inexpensive battery like this comes with a premium feature. The Banshee comes with a built-in Hydrometer which states the current state of your battery life.

Caveats:

Two things to consider for the Banshee is that some boaters prefer AGM for a deep cycle battery. This is a personal preference, I don’t have an issue with EFB, it’s just not as high-end as AGM batteries.

The second thing to think about is that the reserve capacity is lower than the BlueTop. If you don’t spend a long time out on the water, this won’t matter. The difference is 20 minutes, if this is a big deal to you then choose the Optima 34M.

Verdict:

Buy the Banshee 34M if you need a cheap replacement for the Optima BlueTop. It is a perfect fit and has higher amp hours that the BlueTop. Sounds like a great deal to me!

Popular Group 34 Dual Purpose Battery

Photo of Grey Optima BlueTop Dual Purpose Battery

Optima 8016-103 D34M BlueTop

Group 34 Dual Purpose Marine Battery
Amp Hours (AH): 55
Reserve Capacity (RC): 120 minutes
Dimensions (inch): (L)10.06 X (W)6.88 X (H)7.94
Weight (lbs): 43.5
Cold Cranking Amps (CCA): 750
Marine Cranking Amps (MCA): 870
Internal Resistance (fully charged): 0.0028 ohms
Fifteen times more resistant to vibration for durability
Dual SAE Posts & 5/16 Stainless Steel Studs

What We Like

What We Do Not Like

Optima 8016-103 34M BlueTop Review:

Optima as a brand name is popular for powering trolling motors. Boaters like their dual-purpose versatility combined with the decent price.

Spiral Cell Technology

The Optima 8016-103 34M (BlueTop) uses a patented internal cell construction called “spiral cell.” This is a series of individual spiral-wound cells; within each cell are two special plates. Each plate is near pure (99.99%) lead, and coated in lead oxide. One of the coated plates is positive and the other is negative. This translates into consistent and reliable energy along with good durability.

This dual-purpose marine battery gives good amp hours of 55ah with a reserve capacity of 120 RC. It will kick-start small to medium motors in frigid weather. Plus, a tester states that it lasted around 11 hours during heavy deep cycle use. The brand states it is 3 times stronger than conventional group 34 wet cell batteries. But for 2021, I found the Banshee battery meets the BlueTop’s performance for less money.

What boaters love about the Optima BlueTop is its size and weight. Its dimensions are 10” x 6 7/8” x 7 13/16” and weighs as little as 43.5 pounds (19.73 kg). With this size and weight, it is effortless for one person to mount it or dismount it.

Any Compromises of the Optima BlueTop Battery?

One compromise to note is for those boaters interested in the starting ratings of the Optima 34M. With a marine cracking amps rating of 870 and cold cranking amps of 750. These ratings are lower than other available group 34 batteries.

The other downside is that it’s best to use a specific Optima re-charger to keep it from overcharging. Buyers will also need to be careful about following the unique charging instructions. This may be a nuisance for some inexperienced boaters.

Verdict:

Expect the Optima 8016-103 34M BlueTop to be a capable AGM trolling motor battery that won’t break the bank.

Top Dual-Purpose Battery - Below 25 lbs Thrust

Odyssey 34M PC1500ST Trolling Thunder

Made in the USA
Group 34 Dual Purpose Marine Battery
Amp Hours (AH): 68
Reserve Capacity (RC): 135 minutes
Dimensions (inch): (L)10.85 X (W)6.76 X (H)7.95
Weight (lbs): 49.5
Pulse (5-second) Hot Cranking Amps (PHCA): 1500
Cold Cranking Amps (CCA): 850
Cycle life @ 77° F 400 at 80% D.O.D
-40°C (-40°F) to 45°C (113ºF) Temperature Range
Terminals: brass SAE posts 3/8 inch positive, 5/16 negative thread SS stud terminals

What We Like

What We Do Not Like

Odyssey 34M-PC1500ST Review:

The Odyssey 34M-PC1500ST is like the little brother of the 31M PC2150-ST. It’s a group 34 dual-purpose trolling motor battery and is direct competition to the Optima 34M. I call it the little brother because it has the same internal makeup as the larger Odyssey. The differences are that it has less amp hours at 68 ah, 120 reserve minutes, and also it is 28.3 pounds (12.84 kg) lighter.

Inside this Odyssey are multiple thin flat plates and like its big brother are 99.99% pure lead. These plates have specialized glass mat separators soaked in electrolyte solution. Remember, more plates means more plate surface area to interact with the electrolyte. As a result, the battery gives you more power.

Starts Like A Champ!

This dual-purpose battery gives engine-cranking pulses of more than 1500 amps for 5 seconds. This will crank a motor in frigid temperatures and harsh environments. As for deep cycle applications, expect 400 cycles at 80% DOD (depth of discharge). This is double to triple that of equal sized conventional wet cell batteries.

Likewise, it has tin-plated SAE posts and stainless steel stud terminals. This will help reduce terminal corrosion that plagues many cheap batteries. Furthermore, it is US Department of Transportation classified as a sealed battery.

One of the best things we like about the Odyssey PC1500-ST is its long shelf life. This means you can store it on open circuit without the need for recharging up to 2 years. Although it’s ideal, to store marine batteries on a trickle charger.

Downsides Of The Odyssey 34M:

One downside of this battery is that it has a higher initial price compared to similar batteries. Another is to be careful during recharging, since overcharging causes damage to the battery.

Verdict:

Purchase the Odyssey PC1500-ST if you value an extreme combination of power and performance. It’s a near perfect battery for small to medium boats with accessories and a trolling motor.

What To Look For In A Trolling Motor Battery:

Are you looking to buy a trolling motor battery? It is important to know that it is different from starting or cranking battery. A trolling motor battery will sip constant power over an extended period. On the other hand, a starting battery provides short bursts of energy to help crank a motor.

Don’t use a starting battery for trolling; it leads to overheating and failure of the battery. This isn’t something you want to happen while on the water. It is crucial to choose the right type and ratings. Using the proper type will help to achieve a long lifespan for your battery and trolling motor.

Marine Battery Types: Dual-Purpose Versus Deep-Cycle

For trolling motors, it is best to choose either a dual-purpose battery or a deep-cycle battery. As the name suggests, dual-purpose batteries provide both starting and deep cycling duties. This do-everything battery offers good, albeit not great deep-cycle performance. For boats with limited space, with room for one marine battery, it’s a satisfactory compromise.

While dual-purpose batteries offer power solutions for smaller boats, for bigger boats, use separate deep-cycle batteries. This is because the purpose of a deep-cycle battery is for gradual release of power over time. Due to this, a deep cycle batteries’ life cycle is longer than a dual-purpose battery for a trolling motor. Although there are exceptions to this, as a couple premier dual-purpose types have proven to be better than cheaper deep cycle batteries.

What type of trolling motor battery you choose will have to be a personal decision based on your needs. If you want one do-it-all battery, you can choose a dual purpose. Otherwise, if you need a separate battery for only a trolling motor, buy a deep-cycle battery.

Related: How To Choose A Boat Battery

Beyond picking a type of battery you need to consider the following sub-factors for a trolling motor battery. These include cell chemical type, power system and battery ratings.

Cell Chemical Type: Flooded vs. Gel vs AGM vs Lithium

First, decide which battery chemistry meets your needs. Each type of chemical makeup inside marine batteries has its own pros and cons. For 2021, I include both AGM and an enhanced flooded battery to help keep costs manageable for wallet conscious buyers.

Absorbed Glass Mat or AGM use glass sheets as separators for the lead plates. The plates and separators soak in electrolyte solution, absorbing and suspending the solution. As a result, the suspended electrolyte always stays in contact with the plates. As a result, an AGM battery produces electricity the same as the older flooded batteries. Likewise, it is spill-proof and the most vibration resistant lead-acid battery available today.

Flooded Enhanced Batteries are an upgraded version of a Wet cell. While less expensive than AGM, they aren’t as popular either.

Power System:

Next, you should consider the power or voltage of the trolling motor battery. Marine Batteries power ratings are in volts; and are available in 12 volts, 18 volts or 24 volts. This means that if your trolling motor requires 24 volts of power, you will need either two 12-volt batteries or one 24-volt battery. Choosing 24-volt batteries is up to the buyer, but they are expensive and large. Since boating is expensive, we only focus on 12-volt batteries for this article.

Trolling Motor Battery Ratings:

The third factor after you choose a type of trolling motor battery, is to look at the ratings. Like most ratings you see, higher is better, it’s in your best interest to choose the highest ratings within your budget.

Below are the four most important ratings for buying a trolling motor battery:

Amp Hours (AH)
Reserve Capacity (RC)
Group Size
Weight

1. Amp Hours (Ah)

This is one of the most important ratings to look for in buying a trolling motor battery. The amp hours rating indicates how much amperage is available when discharged evenly over a 20-hour period. The measurement of amp hours are essentially in units of energy.

In simple terms (For a mathematical explanation click here):

“The number of amp hours indicates the storage capacity of electricity inside battery”.

If you prefer to shop for dual-purpose batteries, you may not see an AH rating. In general, small dual-purpose batteries will have a rating of 25 to 55 Ah. While large group size deep cycle batteries are from 55 to 100 Ah plus.

Choosing a higher amp hour rating provides longer usable power before needing recharging.

2. Reserve Capacity

The reserve capacity (RC) rating is a measurement in units of time (minutes). Calculated by counting the number of minutes a new battery can maintain 25 amps draw until the battery goes from full to flat. The test to find this rating uses a battery in an environment of 80 °F (26.67 °C). The battery is flat when the voltage drops below 10.5 volts.

For example:

Consider a Group 27 deep-cycle battery with a reserve capacity rating of 180 minutes. With this 180 RC rating, it can provide a 25-amp load for about three hours.

Like the amp hour ratings, it is best to look for the highest RC rating you can afford. Average deep-cycle and dual-purpose batteries have a 90-minute RC. While satisfactory, try to choose the highest RC rating you can afford.

3. Group Size

Group size refers to a battery’s physical size and every manufacturer builds to a general “group size.” Although, differences occur between manufactures due to specific handles or post height. Therefore, it is important to confirm how much battery space you have on your boat. These are some common group sizes, from small to large: 24, 27, 31, 34, 6D, 8D, etc.

For this article, we focus on Group 27-34 since these perform the best for most trolling motors.

4. Weight

While most boaters want to lighten their boat, it is in fact beneficial to use a heavy marine battery. The heavier the marine battery is, the larger the lead plates are and more lead translates to more power.

In Conclusion:

Choosing a power source for your trolling motor doesn’t have to be difficult. Take note of what power source meets the needs of both your trolling motor and vessel. Always choose the battery that offers the highest amp hour and reserve capacity ratings. Also, don’t forget to factor in the length of time spent on the water, and how you plan to charge the battery.

In the end, we do the research so you can spend more time out enjoying the water.

Best Trolling Motor Battery (2021 Reviews Guide)

Trolling Battery Comparison Chart

The Best Group 27 Deep-Cycle Battery

Review of the VMAX MR-127:

Three Important Advantages of a VMAX Deep Cycle Battery:

Three Caveats:

Verdict:

USA Military Spec Deep-Cycle Trolling Battery

Lifeline GPL-27T Review:

Industry Leading Performance

Disadvantages For The Lifeline Deep Cycle Battery:

Verdict:

Budget Friendly Group 27 Trolling Motor Battery

Universal UB121000 Review:

Features of the Universal Trolling Motor Battery

Caveats & Suggested Improvements

Verdict:

The Best Group 31 Dual-Purpose Battery

Odyssey 31M Trolling Thunder Review:

Who is Odyssey Batteries?

Dual Purpose Trolling Motor Battery

Verdict:

Excellent For Trolling Motors Above 55lbs Thrust

Northstar NSB-AGM31 Review:

Best Deep Cycle Battery You Haven’t Heard Of

Any Disadvantages?

Verdict:

Highest Reserve Capacity (RC) Group 31 Deep Cycle Battery

VMAX MR-137 Review:

High Performance Reliability

Negatives of the VMAX MR-137:

Verdict:

Most Affordable Group 34 Deep Cycle Battery

Banshee 34M Review:

What Is An “Enhanced” Flooded Battery (EFB)?

2 Key Features Of EFB:

Inexpensive & Rugged

Caveats:

Verdict:

Popular Group 34 Dual Purpose Battery

Optima 8016-103 34M BlueTop Review:

Spiral Cell Technology

Any Compromises of the Optima BlueTop Battery?

Verdict:

Top Dual-Purpose Battery - Below 25 lbs Thrust

Odyssey 34M-PC1500ST Review:

Starts Like A Champ!

Downsides Of The Odyssey 34M:

Verdict:

What To Look For In A Trolling Motor Battery:

Marine Battery Types: Dual-Purpose Versus Deep-Cycle

Cell Chemical Type: Flooded vs. Gel vs AGM vs Lithium

Power System:

Trolling Motor Battery Ratings:

1. Amp Hours (Ah)

2. Reserve Capacity

3. Group Size

4. Weight

In Conclusion:

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