How To Choose A Trolling Motor Battery [Expert Tips]

Personally, I am a fan of lithium batteries due to their excellent energy density and hence lighter weight in comparison to the equivalent AGM or lead-acid battery. Here’s a quick snapshot of what this guide covers:

At a Glance:

1️⃣ Understanding the different types of batteries for trolling motors is crucial. Lead-Acid Batteries, AGM Batteries, and Lithium Batteries, each with advantages and disadvantages.

2️⃣ The choice of trolling motor battery should be influenced by factors like budget, desired performance, and maintenance requirements.

3️⃣ For different boat sizes and types of fishing, the power needs vary, affecting the optimal battery choice for your trolling motor.

Selecting the appropriate battery for your trolling motor is a key decision. So, prior to purchasing one and potentially discovering it doesn’t meet your requirements, consider going through this guide. It’s designed to provide you with essential information to help in your decision-making process.

🔋 Trolling Motor Battery Types

Understanding the different battery types available and their respective pros and cons is the first thing you need to know. Three popular battery types for trolling motors are Lead-Acid Batteries, AGM Batteries, and Lithium Batteries.

Battery TypeDescriptionAdvantagesDisadvantages
Lead-Acid BatteriesMaintenance-free, longer life, and better resistance to vibration compared to wet-cell batteries.Cost-effective, steady voltage output.Requires regular maintenance (adding distilled water, cleaning terminals), lower energy density (larger and heavier for the same capacity).
AGM BatteriesA type of sealed lead-acid battery. Stands for Absorbent Glass Mat.Requires regular maintenance (adding distilled water, cleaning terminals), and lower energy density (larger and heavier for the same capacity).May be more expensive than lead-acid batteries.
Lithium BatteriesThe newest addition to the trolling motor battery market, specifically Lithium Iron Phosphate (LiFePO4) batteries.High energy density (lighter and smaller for the same capacity), maintenance-free, stable voltage output, longer life cycle.May be more expensive initially.

Remember, the type of trolling motor battery that you choose should depend on your specific needs and preferences, including factors like budget, desired performance, and maintenance requirements.

🎯 Selecting the Right Battery

Boat Size and Weight

A larger and heavier boat will require a more powerful battery with a higher amp-hour rating. 

For example, a small boat with a lighter weight might work well with a 100 amp-hour battery, while a larger boat may require a battery with a 150 amp-hour rating. 

It’s crucial to select a battery that can provide enough run time for your trolling motor, considering the boat’s size and weight.

Here are some recommendations for selecting a battery based on boat size:

  • Small boats (less than 12 feet): 80-100 amp-hour battery
  • Medium boats (12-16 feet): 100-150 amp-hour battery
  • Large boats (over 16 feet): 150-200+ amp-hour battery

Fishing Priorities

Different types of fishing may have different power needs, affecting the optimal battery choice for your trolling motor. 

For example, if you are fishing for bass on a freshwater lake will have lower power requirements than if you are trying to stay over a reef drop-off with a strong rip current.

In summary:

  • For casual fishing, a more affordable and widely available lead-acid battery may be sufficient.
  • For more demanding fishing conditions, a lithium-ion or AGM battery with a longer run time and low maintenance needs may be the better choice.

⏱️ Battery Capacity and Run Time

Battery Capacity

A higher-capacity battery can provide more energy to your trolling motor, allowing it to operate for longer. Battery capacity is measured in amp-hours (Ah), and it determines the amount of energy the battery can store.

To calculate the run time of a trolling motor battery, divide the battery’s amp-hours rating by the number of amps the motor draws at a given speed. 

For example, if you have a 100 Ah battery and your trolling motor draws 20 amps, the run time would be approximately 5 hours (100 Ah / 20 amps = 5 hours).

Keep in mind that it’s crucial to match the voltage of your battery with the voltage requirement of your trolling motor when deciding what size battery to get. 

Common trolling motor voltages are 12V, 24V, and 36V, and the necessary thrust can be achieved by choosing the appropriate battery capacity. 

The general rule of thumb is that more voltage results in higher thrust, allowing your boat to move faster and combat stronger currents.

Battery Life

Different types of batteries have varying energy densities and reserve capacities.

Energy density refers to the amount of energy stored per unit of volume or weight, while reserve capacity (RC) is the amount of time a battery can deliver a certain amount of power before its voltage drops below a specific threshold.

For trolling motors, using a battery with at least a 100 Ah rating, a Group 27 rating, and 175 minutes of Reserve Capacity is a good option. This ensures an optimal balance of performance and longevity.

When it comes to battery life, it’s also important to consider the battery’s depth of discharge (DoD), which is the percentage of its total capacity that’s used before recharging, is an important factor to consider for this. 

In our calculations, we assume an 80% depth of discharge, meaning the battery will still have 20% remaining capacity. This is a recommended value for lithium batteries, as it helps prolong their lifespan.

If you have a solar setup and are concerned about whether using it will affect your battery’s health in the long term. Don’t worry. Using solar panels to charge your trolling motor battery won’t affect its longevity, and it’s actually a great way to reduce costs in the long run.

💰 Cost Considerations

Budget is arguably the most important factor for a lot of anglers. There are several factors that can impact the cost of a trolling motor battery, and understanding these factors can help us make the best decision for our needs.

First, we should consider the type of battery we want to purchase. Lead-acid wet-cell batteries are the most affordable option but have a shorter lifespan and require regular maintenance. 

AGM batteries are more expensive than lead-acid wet-cell batteries but offer a longer lifespan and are maintenance-free. 

Lithium-ion batteries are the most expensive but provide the longest lifespan and most efficient performance.

Another factor to consider is the battery’s amp-hour rating, which impacts the battery’s capacity and runtime. 

Higher amp-hour ratings typically come with a higher price tag, but they also provide longer runtime for our trolling motor.

So balance your budget constraints with the desired runtime to find an option that meets your needs.

Size is another aspect that can affect the cost of a trolling motor battery. Larger batteries often have greater capacities and can run trolling motors for longer periods, but they also tend to cost more. 

Finally, you get what you pay for. Some well-known brands offer higher-quality batteries that come at a higher cost.

While it can be tempting to save money with a more affordable battery from an unknown brand, it’s important to research the battery’s performance, reliability, and lifespan before making a decision.

💪 Battery Durability and Longevity

Your battery’s lifespan can vary significantly depending on its type, quality, and usage. One of the key aspects to think about is the battery’s resistance to corrosion.

Over time, corrosion can reduce a battery’s performance and shorten its life. To minimize corrosion, look for batteries constructed with high-quality materials and designed for marine applications.

Most trolling motor batteries are not designed to get wet and will end up dead and corroded if you try to use them in the wrong scenario.

Another factor influencing durability is resistance to vibration. Trolling motor batteries are often subjected to continuous vibrations on the water.

Batteries that are designed to be shock-resistant and have robust housing can better withstand these vibrations and have a longer service life.

In terms of longevity, it’s essential to consider the battery’s efficiency. Higher-efficiency batteries deliver more power output for the same amount of charge, making them more cost-effective in the long run. Efficient batteries can also provide consistent performance throughout their lifespan.

Lithium-ion batteries are gaining popularity due to their impressive durability, longevity, and efficiency. 

These batteries typically offer longer service life than their lead-acid counterparts, with some models lasting up to 15 years or more. Additionally, they are more resistant to corrosion and perform well in terms of efficiency.

Here’s a quick comparison of factors to consider for trolling motor battery longevity:

  • Corrosion resistance: Look for high-quality materials and marine application design.
  • Vibration resistance: Choose batteries with robust housing and shock-resistant features.
  • Efficiency: Opt for higher efficiency batteries to get more power output and consistent performance.
  • Lithium-ion technology: for their impressive durability, longevity, and efficiency.

🔢 Choosing the Right Motor and Battery Combination

This. Is. Key! Consider the type of battery, its capacity, and compatibility with the motor.

Firstly, it’s important to understand that trolling motors require specific types of batteries. You can’t, for example, buy a car battery and expect it to work.

Deep cycle batteries are the most suitable option since they’re designed to provide a steady amount of current over a long period of time. They differ from regular starter batteries (found in cars), which are meant to deliver high bursts of power for a short time.

Deep cycle batteries come in different sizes and capacities. One popular option is the Group 27 deep cycle marine battery, which has a minimum of 110 ampere-hours. 

The higher the ampere-hour or reserve capacity of a battery, the longer it will last during your fishing trips.

Motor Voltage

Motor voltage: Trolling motors generally come in 12V, 24V, and 36V options. Pick a battery with the appropriate voltage that matches your trolling motor. For instance, a 12V battery should be paired with a 12V motor.

Installation and Compatibility

Next, I’ll touch on cold-cranking amps, cranking torque, voltage drop, low speed, and maneuverability.

First, let’s look at installation specifications. For example, when connecting batteries in series to achieve a higher voltage, use a connector cable with the appropriate size and gauge to link the positive and negative terminals. 

This will help minimize voltage drop and maintain the necessary power for high-performance trolling motors. Additionally, ensure that the trolling motor lead wire is one size larger than the jumper wire used, as explained by Minn Kota’s battery installation guide.

Cold-cranking amps (CCA) highlight the battery’s ability to deliver high power for a short time. This is essential for maintaining cranking torque and maneuverability, especially in low-speed maneuvering.

A battery with a high CCA will ensure that your trolling motor can perform optimally, even in colder conditions.

Lastly, it’s important to choose the right battery capacity based on the expected usage and thrust of your trolling motor.

For most trolling motors with 30 to 55 pounds of thrust, a lithium-ion battery with a capacity between 50-100 Ah should be sufficient.

🔑 Key Takeaways

1️⃣The cost of the trolling motor battery is a major consideration. Lead-acid wet-cell batteries are affordable but require regular maintenance, while Lithium-ion batteries are the most expensive but offer the best performance.

2️⃣Battery durability and longevity are significant factors, with a focus on corrosion resistance, vibration resistance, and overall efficiency. Lithium-ion batteries stand out for their impressive durability, longevity, and efficiency.

3️⃣Choosing the right motor and battery combination is based on its capacity, compatibility with the motor, and expected usage. Deep cycle batteries are the most suitable option for trolling motors as they provide a steady amount of current over a long period of time.

I’m the founder and chief editor here at Kite Ship. The electrification of boating is the most exciting thing to happen to the marine industry in a generation! Welcome, and I hope that we can provide the portal you need to dive into the world of electric propulsion and power.