The most critical part of your boat? The battery.
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
To start, you need to know about the different types of batteries. Later, I’ll touch on which type is best for trolling motors.
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.
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 2 batteries measure approximately 11 x 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 which 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 are 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.
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 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 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. 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.
The best in the business, Optima is also the most expensive. A unique feature for the battery industry, they don’t even have fluid and instead, use a fibrous material which allows the battery to function—even if punctured!
The Bluetop 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.
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 lifespan. 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. And 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 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 when you’ll find trouble.
Investing in good batteries will also guarantee good batteries and provide a nicely performing trolling motor.
Now go out there and catch the record catch!