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Feeling Drained? Choose the Right Battery for Your Trolling Motor
Do you struggle with batteries for your electric trolling motor?
Are you constantly dishing out your hard-earned cash every year for new batteries?
Are you getting only a few hours (or worse, a few minutes) out of your trolling motor?
Or are you considering upgrading your boat to have an electric trolling motor and have no idea where to start?
If your head's bobbing yes to any one of these questions, then this article is for you!
The Different Types of Batteries
The battery - the most critical part of your boat. If not for the battery, there's no need for a motor, an anchor or a propeller.
To start, you need to know about the different types of batteries. Later, I'll touch on which type is best for trolling motors.
Cranking Batteries
All car batteries fall into this category as should the main battery for your boat's motor. Cranking batteries are designed to deliver the high amps necessary to start the motor.
They like to maintain a constant charge level and are happiest when they don't become drained (similar to how leaving a light on in your car can harm the battery). Even though it was one little light, that's all it takes to drain.
Deep Cycle Batteries
A deep cycle battery is in your hand and on your desk. Laptops, smartphones and tablets all have what's technically a deep cycle battery.
These batteries can be discharged (or "drained") then recharged back to 100% without negative effects. Fun Fact: 12.7 volts is considered full charge on a battery.
Dual Purpose Batteries
Dual purpose batteries are a hybrid of cranking and deep cycle. For small boats, short trips or wholly different applications, these batteries work well.
But to run a quality trolling motor, they're not the best choice.
Group Types
This isn't a battery type, per se, but rather different families of batteries. The higher the number, the larger and more powerful the battery.
The most common is Group 24, which are your cranking batteries, dual purpose and small deep cycle batteries. Group 24 batteries measure approximately 11x 7 x 9 inches (may vary from brand to brand).
The next size up is Group 27, which is more common for deep cycle batteries. They measure 12 x 7 x 9 inches (or larger). The last battery group to cover is
Group 31 batteries are huge! They measure approximately 13 x 7.25 x 9.25 inches. These batteries are almost too big. But... they provide a lot of power.
Although there are many more battery group types to choose, their uses and characteristics are either specialized or not applicable to trolling motors.
What Makes Deep Cycle Batteries Best for Trolling Motors?
Cranking batteries prefer a constant charge and provide a large burst of energy to start a motor.
Deep cycle batteries prefer to discharge low, then recharge back up. Much like a phone or tablet, they like to go up and down with their power levels. Due to this nature, a deep cycle can last a long time frame on a single charge.
Without beating a dead horse, deep cycle batteries are best because they're designed for the high power demands of today's electric trolling motors. They can handle being discharged down, then recharged at the end of the day, whereas cranking batteries hate this.
Much like oil and water, cranking batteries and trolling motors don't mix.
Which Brand Is Best?
With so many batteries and battery manufacturers out there for the picking, it's hard to decide which is best for your trolling motor. But these are batteries I've had personal experience with and can recommend to those of you who need a place to start.
Basic Batteries
For an emergency or boaters on a budget, this Mighty Max Rechargeable Gel Type Battery (check price on Amazon) is a standard go-to. But for longevity and reliability, don't expect much.
The problem? If you're buying new batteries every year, you'll end up spending more money than the better higher quality brands. While I offer this battery suggestion, I highly recommend just biting the bullet and investing in one of the following.
Interstate Batteries
Interstate has been around since 1952 and is a good quality brand. They offer various deep cycle batteries to choose from.
Some Interstate batteries are open cell batteries, which require fluid top-offs when low. A 12-month free replacement warranty is also a good incentive.
My go-to for this brand is the SRM-27. Simple, reliable and fairly priced. While not the greatest, they work excellently.
Centennial Batteries
Centennial originated around the similar time as Interstate, around 1955. The biggest difference Centennial has from Interstate is their batteries are sealed - no need to check fluids or top-off.
They're more reliable, but also more expensive. I have less experience with Centennial batteries, but I can tell you my customers have been very happy with the DC27MF.
It's more money than other brands, but it's worth getting a sealed battery.
Optima Batteries
The best in the business, Optima is also the most expensive. A unique feature for the battery industry, they don't even have fluid. Instead, they use a fibrous material that allows the battery to function even if punctured!
The Blue top D27M (check price on Amazon) is the best out there in my opinion. If you want the best, these are your best bet. Just prepare yourself for the price.
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The Importance of Battery Care and Maintenance
To avoid yearly battery replacement, it's important to charge them after every use and throughout winter. If you let a battery discharge and not charge properly, it can hurt the battery and shorten its life span.
Granted, if you have unlimited funds and like to buy new batteries every year, all the more power to you. But if you're like me and funds don't grow on trees, take a few minutes at the end of each day to hook up the charger.
Check the battery fluids. If it gets low, top off the battery with distilled water. This is a critical step to prevent the lead plates from being exposed to air, which could result in corrosion. Once there's enough internal corrosion, it'll eventually cause the death of a battery, which is almost impossible to save.
Invest in a good quality charger. It's important to be aware of what your battery is doing, so make a habit to charge after each use. In the off-season, charge once a month.
On a side note, I've had customers try to charge batteries with the main motor while driving back to the harbor, which is normally only 10 to 15 minutes. This is not nearly enough time to give a proper charge. Don't fall into a false sense of security that your batteries are charged.
Charge batteries when they've been pulled down. Also, I don't recommend hooking up your main motor to your trolling motor batteries. Keep your cranking battery separated from the deep cycles.
Charge batteries over the winter. Boaters seem to forget is to charge batteries over winter. Unfortunately, it's when they get neglected, forgotten and abused that you end up having to replace them.
Getting the Maximum Life From Your Batteries
By following the maintenance suggestions, using proper batteries and charging when needed, you'll get many years of use. Taking a few minutes out of your day is all it requires to maintain good reliable batteries. It's when you ignore them or neglect their maintenance that you'll find trouble.