To get the most from your trolling motor, you need reliable, powerful batteries.
Unfortunately, battery tech is confusing, and unless you really do your homework, you’ll shortchange your motor and yourself.
Let’s clear up some confusion right away: while dual-use batteries can power a trolling motor, you won’t get the performance from them that you will from the true deep cycle batteries we discuss here. These are dedicated trolling motor batteries, and as such, can’t do double-duty to start your outboard.
But what they can do is provide reliable, all-day power for your trolling motor, giving you absolutely unrivaled performance!
Interested? Below, you’ll find a complete buying guide, as well as reviews of the top trolling motor batteries.
Quick glance at the best trolling motor batteries:
- VMAX MR127 AGM Deep Cycle - Best Dedicated Trolling Motor Battery
- Interstate Batteries SRM-27
- Interstate Batteries SRM-31
- Lithium Pros M3140-36 36V 40Ah Trolling Battery
Table of Contents (clickable)
Related:
Best Trolling Motor Battery Reviewed
VMAX MR127 AGM Deep Cycle - Best Dedicated Trolling Motor Battery
Type: AGM
RC: 200 minutes
Weight: 68 lbs.
Size: Group 27; 6.75” x 12.1” x 8.2” (8.46” with terminals)
There's a reason why this is the best trolling motor battery. The VMAX MR 127 is a hard battery to beat. Ideal as a dedicated trolling motor power source, with anything like reasonable throttle settings, you’ll have juice to spare at the end of the day! In fact, many anglers find that they barely make a dent in this battery’s power reserves.
Chalk that up to 200 minutes of reserve capacity, a number that’s definitely at the high-end of battery performance. Rest assured, whether you run a 12-, 24-, or 36-volt trolling motor, the VMAX MR127 will provide the power you need, season after season.
This Group 27 battery isn’t a lightweight--a testament to its thick plates.
Pros:
- Dependable
- Awesome RC
- Tolerates deep discharges, season after season
Cons:
- Heavy
Interstate Batteries SRM-27
Type: Wet-cell
RC: 160 minutes
Weight: 50.3 lbs.
Size: Group 27; 6.75” x 12.75” x 9.5”
Long trusted by anglers and battery experts alike, Interstate Batteries’ SRM series are consistently solid performers, delivering the power you need from dawn to dusk. And while certainly not high-tech, these batteries have a well-earned reputation for reliable performance.
If weight is an issue for your boat, and if you don’t mind the extra maintenance issues of old-school, wet-cell tech, the SRM-27 is a good buy. Indeed, if I were running a Jon-boat or small aluminum boat for which added battery weight was an issue, the SRM-27 would be on the top of my list.
This is a great runner up to the best trolling motor battery listed above. Offering no less than 160 minutes of RC while weighing in at only 50.3 pounds, the SRM-27 delivers great performance for the weight and price. And properly maintained, this battery has proven itself dependable year after year.
Pros:
- Dependable
- Good RC
- Inexpensive!
- Light (for a battery)
Cons:
- Lags behind the VMAX in performance
- Requires basic maintenance, including periodic equalization
Interstate Batteries SRM-31
Type: Wet-cell
RC: 210 minutes
Weight: 59.7 lbs.
Size: Group 31; 6.69” x 13” x 9.63”
Interstate Batteries’ excellent SRM series is also available in Group 31 sizes, delivering the same reliable performance as the smaller Group 27.
And before you knock wet-cell tech, consider that this 60-pound battery promises 210 minutes of reserve capacity. That’s the highest number on our list and one of the best performers--pound for pound--money can buy!
And given that its price is reasonable, if you’re prepared to maintain this battery, it’s a very, very good choice for trolling motors.
Pros:
- Dependable
- Great RC
- Inexpensive!
- Light
Cons:
- Requires basic maintenance, including periodic equalization
Lithium Pros M3140-36 36V 40Ah Trolling Battery
Type: Lithium-Ion
RC: 92 minutes
Weight: 30.3 lbs.
Size: Group 31; 6.81” x 13” x 8.43”
If you run a 36-volt trolling motor, you know how expensive buying three batteries at a time can be. They’re also going to eat up valuable space and weigh a ton, giving you less room for tackle and decreasing the overall performance of your trolling motor (and your outboard).
Lithium Pros 36V deep cycle battery is designed to replace an entire bank of lead-acid alternatives, delivering up to nine hours of power to your trolling motor while weighing in at just 30.3 pounds.
That’s ridiculous!
This lithium-ion battery offers 92 minutes of reserve capacity, more than enough for most anglers, especially if you watch your throttle settings.
The downside? Prepare yourself for the price!
Pros:
- Dependable
- Good RC
- Replaces three 12v batteries at only 30.3 pounds!!!
Cons:
- Insanely expensive!
How To Pick the Right Trolling Motor Battery for Your Needs
All batteries are definitely not the same, and picking the right battery for your needs isn’t as simple as it might seem.
For instance, the deep cycle battery you use to power an RV or store energy from a wind turbine isn’t a very good choice for a boat. They’re just not designed to take the pounding they’ll get from waves.
Lots of sites apparently don’t know this!
And that’s just the beginning of the confusion.
While researching, I found plenty of people recommending dual-use batteries as dedicated trolling motor power sources (you’ll get less running time from your trolling motor), suggesting solar or wind turbine deep cycle batteries for boat use (vibration will definitely be an issue!), and generally confusing one battery type or tech with another.
It’s absolutely essential that you understand which battery you need!
Battery Types: Know the Difference!
Deep cycle batteries - are essentially the opposite of a starting battery. Designed with thick, solid plates bathed in a catalyst medium, they can’t produce enough instantaneous power to start an outboard. But they excel at delivering steady power over a long time, making them ideal for trolling motors.
Those thick plates also tolerate deep discharge and recharges well, explaining the name “deep cycle.” You can typically drain a deep cycle battery to just 20 percent of its maximum charge again and again without damage or reduction in efficiency.
These are dedicated trolling motor/electronics batteries, and they’re what you’re looking for.
Starting batteries - are equipped with sponge-like plates that offer maximum surface area to the catalyst that drives the chemical reaction that creates their power. This allows them to produce a very strong burst of energy over short periods, making them ideal for starting engines.
But that ability comes at a cost. With very little plate mass, starting batteries can’t maintain their power levels over prolonged periods, and they’ll quickly discharge if you connect them to a trolling motor.
They’re simply not designed for that.
And like the battery in your car or truck--which is also a starting battery--they need to be more or less constantly recharged via an alternator or on-board battery charger. Letting them discharge and then recharge will quickly damage the battery, resulting in failure.
Dual-use batteries - are the compromise between a starting and a deep cycle battery. Their plates offer enough surface area exposed to the catalyst to deliver an engine-starting burst of power, but they’re also thick enough to deliver reliable electricity to your trolling motor.
As you’d expect, they can’t offer the cold cranking amps of a true starting battery or the long term power and deep discharging of a deep cycle battery. Indeed, taking them below about 50 percent of their maximum charge will affect battery life.
Intended for anglers who need one battery to do it all, these are not the best choice for a dedicated trolling motor battery.
“Marine” batteries - sometimes used as a synonym for “deep cycle,” marine batteries can consist of any of the other types, depending on their purpose.
Battery Tech: Wet-Cell vs. SLA/VRLA/AGM vs. Lithium-Ion
Battery tech has come a long way over the last 20 to 30 years, and you may not be aware of the various kinds of battery systems on the market. Understanding their strengths and weaknesses can help you pick the right one for your needs.
Sealed Lead-Acid (SLA), Valve-Regulated Lead-Acid (VRLA), and Absorbed Glass Mat (AGM) - Essentially three terms for the same chemical system, SLA/VRLA batteries use lead plates and acid as their basic components. AGM batteries add one additional chemical trick. The result of this tech is that they’re all heavy and safe--and that they don’t require the maintenance of traditional wet cell batteries.
These batteries hold a charge well, but they are quite a bit more expensive than typical wet-cell alternatives, and they can be damaged by overcharging.
Gel batteries - Gel batteries also use lead plates and acid, but the addition of silica to the electrolyte turns it into a thick gel. This provides them with superior long-term storage capacity, and like standard AGM batteries, they’re very safe and maintenance-free.
But they don’t like sudden, powerful discharges, which can lead to damage to the plates. And they must be recharged carefully, never exceeding a maximum charge.
Lithium-Ion (Li-ion) - These batteries trade up from lead and acid to carbon and lithium salts to deliver power. The result is that they’re easily rechargeable and generally smaller and lighter than the SLA or AGM batteries of the same power. They’re simply better battery tech.
The downside? They can be insanely expensive, and 12v systems designed for marine use can cost thousands!
Wet-Cell Batteries - Wet-cell batteries have remained pretty much unchanged since their introduction in the late 19th century. Their low initial price point has kept them popular, and if cared for, they can survive quite a few charging cycles. They’re also resistant to damage from overcharging and weigh in a bit under typical SLA or AGM alternatives.
But they require proper ventilation, can leak and spill acid, don’t hold a charge as well in storage, and can be damaged by the vibrations typical in marine use.
What We Consider When Selecting a Trolling Motor Battery
Reserve Capacity
As Simon Slayford of Hunker explains, “Reserve capacity is defined as the number of minutes a fully charged 12-volt battery at 80 degrees Fahrenheit can provide 25 amperes at 10.5 volts until the voltage decreases.” Essentially, it’s a measure of a battery’s power output over time when not being charged by an alternator or on-board battery charger
You may have heard that RC is “just a number.” And while it is true that the RC doesn’t give you an accurate estimate of the number of minutes a battery will power your trolling motor, higher RCs do mean more power over time.
Look for batteries with the highest RCs you can afford.
Durability
Even well-cared for batteries take a beating from the summer sun, and high temps will definitely reduce their capacity. Vibration is also a problem for wet-cell batteries, and all the shaking and bumping on your boat will do them no favors.
By contrast, car batteries work in a pampered environment, and it’s important to keep that in mind.
For your boat, you need nails-tough batteries to provide dependable power all the time, every time.
Price to Performance Ratio
You typically get the performance you pay for, and that’s as true for batteries as it is for anything else.
Less expensive batteries typically offer lower reserve capacity, shorter service life, and greater maintenance issues than more expensive batteries. But more battery than you actually need may be wasted money.
It’s important to assess your trolling motor habits. How long do you typically run your trolling motor? At what throttle setting? Have you had problems with your batteries running dry in the past--or do you return to the boat launch with power to spare?
Answers to these questions can help you find the right balance of price and performance for you.
Service Life
Despite the design improvements and technical wizardry you’ll find in modern deep cycles batteries, they just won’t last forever.
It’s important to be realistic about this: even the most expertly maintained deep cycle battery will need replacement, typically within 5 years.
But you can probably squeeze extra seasons from a lithium-ion system, as the tech is superior in this sense.
That’s an important point to consider: upfront costs are divided over the years of service life your battery provides, and a model that costs more now may be the better buy over the long run.
Maintenance Issues
All batteries demand reasonable maintenance:
- Charge your battery after each use
- Never discharge your battery fully
- Use a multi-stage charger to provide the right voltage at the right time
- Store your batteries in cool, but not ice-cold temperatures
- Never store an uncharged battery
- Keep the terminals clean
Beyond that, wet lead-acid batteries need to have their water levels checked regularly, and you need to top them off as necessary. You’ll also need to invest in a charger that can equalize them regularly, essentially delivering a slight overcharge to clean the plates of sulfate crystals.
This isn’t a major added time-suck, but wet batteries do require slightly more care than other types.
Weight
Even “lightweight” batteries are heavy, and the heavier your boat, the more this matters. With a large enough bank of batteries in a heavy fiberglass bass boat, outboard performance can suffer.
This is something to think about when you’re deciding how large a bank of batteries to run, and it can really help justify the added cost of lithium-ion batteries.
Size
Measure carefully--a battery that doesn’t fit won’t do you any good! And don’t just measure the space for the body of the battery: take the terminals into account, too!
Batteries come in multiple sizes called “groups,” though dimensions can vary.
In practice, batteries within a given group will have slightly different dimensions, so never assume.
