You may have heard of a lithium trolling motor battery on the fishing circuit. You may have even heard of some of their benefits from fellow fishermen. But what really is a lithium trolling motor battery?
Trolling Motors and Batteries
When you hit the water for a long day of fishing, the last thing you want to worry about is your trolling motor dying on you by lunchtime. Designed to deliver a slow, steady discharge of power, trolling motor batteries need to provide consistent power over a long period to keep that motor running.
Marine lead-acid wet cell, absorbed glass mat (AGM), and gel cell deep-cycle batteries have long been the choice of fishing enthusiasts. But there’s a new option available that offers some desirable advantages. Let’s take a closer look at the lithium trolling motor battery!
What is a Lithium Trolling Motor Battery?
A lithium trolling motor battery is a lithium iron phosphate (LiFePO4) deep-cycle battery. It is made to provide slow, steady power to trolling motors. Most lithium trolling motor batteries are 12 volts, but 24-volt batteries are available as well.
What Kind Of Battery Do I Need For A Trolling Motor?
Batteries connected in series have their voltages added together. For example, two 12-volt batteries connected in series will provide 24 volts and 3 will provide 36 volts. Batteries connected in parallel will have their capacities, measured in amp-hours (Ah), added together. For example, two 12-volt batteries with 100 Ah capacities connected in parallel will provide 200 Ah at 12 volts.
Trolling motors typically run on 12, 24, or 36 volts, depending on the model.
For a 12 volt trolling motor, you could use a single 12-volt battery or multiple 12-volt batteries connected in parallel to extend your run time. For a 24-volt motor, you could either use a single 24-volt battery or connect two 12-volt batteries in series. Lastly, for a 36-volt trolling motor, the most common configuration is three 12-volt batteries connected in series.
Most trolling motors will operate with any 12-volt wet cell, AGM, gel cell deep-cycle marine battery, or lithium battery. However, as we will see shortly, the lithium batteries provide some significant advantages over the other 12V battery types.
Advantages Of Lithium Trolling Motor Batteries
Lithium trolling motor batteries have substantial advantages over the lead-acid wet cell, AGM, and gel cell deep-cycle batteries. But longer run time is the greatest benefit. Typically, a lithium battery will provide about twice the run time on a single charge as a lead-acid battery of the same capacity.
Other advantages of lithium batteries are an extended lifespan, significant weight reduction, and increased efficiency. They also have a longer warranty, and a built-in battery management system (BMS).
Let’s dig into each of these a bit more:
Longer Run Time
While you are using your traditional deep-cycle lead-acid battery for trolling, the battery voltage will drop as it’s discharged. By the time about 50% of the battery’s amp-hour capacity is used, the voltage will have dropped enough that it can no longer power your trolling motor.
Lithium batteries have a flatter voltage curve which means they do not experience this same voltage drop as you use the battery. Since the voltage remains consistent throughout the discharge cycle, you can use the entire amp-hour capacity before your motor stops running.
The flat voltage curve effectively doubles your run time on a lithium battery versus a lead-acid battery with the same amp-hour capacity.
As lead-acid batteries repeatedly go through charge and discharge cycles, they can never be fully charged to their capacity. Over time, they slowly wear out until the voltage drop mentioned above is too great. Then the battery can’t power your motor any longer, even on a full charge.
Lithium batteries don’t last forever, but they typically last for five to ten times as long as lead-acid batteries. This is because of their flat voltage curve and how they’re built. Lithium batteries have the advantage of being a true deep cycle battery with minimal degradation to their lifespan. Unlike all lead-acid batteries that get damaged with each deep discharge, minimal degradation to the life cycle will occur if you use them up each time.
Lithium batteries are about half the weight of regular deep-cycle marine batteries. And weight is a big deal for boaters!
The total weight of the gear and passengers in a boat impacts the craft’s handling and performance. It can even become a safety and legal issue if overweight.
A typical marine lead-acid battery weighs 60-70 pounds. By contrast, a marine lithium battery weighs about 30 pounds. A lithium battery system could save you about 100 pounds for a 36-volt motor requiring three 12-volt batteries connected in series. That’s a lot of fish!
More Efficient Power & Charging
When you combine the significant reduction in weight and additional run time you get from lithium batteries, you end up with a much more efficient system. If you compare the run time per pound of battery, you get about four times the efficiency.
Additionally, lithium batteries can fully charge in about two hours which is significantly faster than their lead-acid counterparts.
Built-In Battery Management System
Battle Born lithium trolling motor batteries come with a built-in battery management system (BMS). This internal BMS monitors and manages temperatures, performance, and charge rates to keep the battery operating safely and increase its longevity.
Lead-acid batteries can have internal shorts, damage from high or low temperatures, and, as noted above, suffer from the effects of improper charging. However, lead-acid batteries do not have a battery management system to monitor performance or act as a failsafe.
10 Year Warranty
Battle Born lithium batteries generally come with a 10-year warranty. Compare this to lead-acid batteries, which usually only have a 1-2 year limited warranty. This is a clear indication that lithium battery manufacturers anticipate a very long lifespan.
Are Lithium Trolling Motor Batteries Worth It?
Traditional deep-cycle batteries cost about one-third of what a lithium battery of the same capacity costs. However, when you factor in that lithium batteries last 50-100 times longer, provide double the run time, and can cut your battery weight in half, the upfront cost savings don’t seem worth it.
Over ten years, you will likely end up replacing your lead-acid batteries enough times to recover the cost of switching to a lithium system. As a bonus, your boat will be lighter and you’ll have more time out on the water doing what you love.
Head For The Water With Confidence
When you’re ready to head for the water with your fishing gear, having reliable lithium trolling motor batteries on board will let you fish from morning to night without worrying about your trolling motor’s battery dying. That’s a win for any fishing enthusiast!
Want To Learn More About Electrical Systems and Lithium Batteries?
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