What Size Marine Battery Do I Need for a Trolling Motor?

What Size Marine Battery Do I Need for a Trolling Motor?As a boating enthusiast, you probably understand the importance of having a reliable marine battery to power your trolling motor. However, selecting the right size marine battery can be a daunting task. You want to ensure that your battery is powerful enough to run your trolling motor efficiently without compromising its longevity. In this section, we’ll guide you through the process of selecting the appropriate size marine battery for your trolling motor, taking into consideration the various factors that influence your decision.

It’s crucial to have a clear understanding of the power requirements of your trolling motor, the different types of batteries available for trolling motors, and how battery capacity, voltage, weight, and maintenance impact your choice. By the end of this section, you’ll be better equipped to make an informed decision on the size of marine battery that best suits your trolling motor requirements. So, let’s dive in!

Trolling Motor Power Requirements

Before selecting a marine battery for your trolling motor, it’s important to understand the power requirements of your motor. The power requirements depend on factors such as the motor thrust and boat size.

Motor thrust is the force that propels the boat through the water and is measured in pounds (lb). The amount of motor thrust required depends on the weight and size of the boat. A larger boat or one with a heavy load requires more thrust to move through the water.

Boat size is another critical factor in determining the power requirements of your trolling motor. A bigger boat needs a more robust motor with higher thrust to maintain speed and control. A smaller boat can use a less powerful motor with lower thrust.

Boat Size Motor Thrust
Less than 14 feet 30-40 lb
14 to 16 feet 40-55 lb
16 to 19 feet 80-101 lb
19 to 21 feet 101-112 lb

The above table summarizes the recommended motor thrust for different boat sizes. Keep in mind these values are only estimates and may vary based on the specific boat’s weight, load, and other factors.

By understanding the power requirements of your trolling motor, you can select a marine battery that can efficiently power it for extended periods without compromising performance.

Battery Types for Trolling Motors

When it comes to selecting a battery for your trolling motor, there are different types of marine batteries available on the market. The three most common types are deep cycle, starting, and AGM batteries.

Deep cycle batteries are specifically designed to provide a steady amount of power over an extended period. These batteries are ideal for trolling motors as they can offer long-lasting power to keep you on the water for longer. They are also built to handle frequent charging and discharging cycles without losing their capacity or performance over time.

Starting batteries, on the other hand, are designed to deliver a quick burst of power to start an engine. They are not recommended for trolling motors as they can quickly discharge and may not have enough capacity for prolonged use.

AGM batteries are a popular choice among trolling motor enthusiasts as they combine the best features of both deep cycle and starting batteries. AGM stands for “Absorbent Glass Mat,” which means the battery uses a fiberglass mat to absorb the electrolyte, making it spill-proof and maintenance-free. AGM batteries offer fast charging rates, deep cycling capabilities, and a long lifespan, making them one of the most reliable options for trolling motors. They are also suitable for boats with limited space as they are compact and lightweight.

Comparison Table of Battery Types for Trolling Motors

Battery Type Advantages Disadvantages
Deep Cycle – Ideal for long-lasting power
– Can handle frequent charging and discharging cycles
– Maintains capacity and performance over time
– Not suitable for quick bursts of power
– May be heavier and bulkier than other options
Starting – Provides quick bursts of power for engine startup
– Generally less expensive than deep cycle batteries
– Not recommended for prolonged use
– Can quickly discharge and lose capacity over time
AGM – Offers fast charging times
– Can handle deep cycling
– Spill-proof and maintenance-free
– Compact and lightweight design
– More expensive than other options

Choosing the right battery type for your trolling motor depends on your specific needs and budget. Deep cycle batteries are a reliable option for those who need long-lasting power, while AGM batteries offer the best of both worlds with their fast charging rates and deep cycling capabilities. It’s important to consider the advantages and disadvantages of each type before making a decision.

Battery Capacity and Runtime

The battery capacity, measured in ampere-hours (Ah), is an important factor to consider when selecting a marine battery for a trolling motor. The battery capacity determines the runtime of your trolling motor, which is how long it can run before it needs to be recharged.

To calculate the required battery capacity for your trolling motor, you need to consider the expected runtime you desire for your fishing trips. The higher the ampere-hours, the longer the runtime of your trolling motor.

For example, if you want your trolling motor to run for six hours, you will need a marine battery with a capacity of at least 75 Ah, assuming a 12-volt battery. If you have a 24-volt battery system, you will need two batteries with a capacity of at least 37.5 Ah each.

It’s important to note that the actual runtime of your trolling motor will depend on various factors, including the speed at which you are traveling, the weight of the boat, and the water conditions.

To maximize the runtime of your trolling motor, consider investing in a deep cycle battery. Deep cycle batteries are designed to discharge slowly over an extended period, providing a consistent output of power to your trolling motor, unlike starting batteries, which are designed to deliver short bursts of power to start an engine.

Always choose a marine battery with a higher capacity than you think you will need to ensure you have enough power to complete your fishing trips.

Understanding Battery Voltage

Battery voltage is a critical factor to consider when selecting a marine battery for your trolling motor. Voltage is the measurement of electrical potential difference between two points in a circuit. In the case of batteries, voltage is the amount of electrical force generated by the chemical reactions within the battery cells.

The most common battery voltage options for trolling motors are 12-volt, 24-volt, and 36-volt batteries. The voltage rating of your battery determines the performance of your trolling motor. The higher the voltage, the more power your trolling motor can deliver.

Battery Voltage Motor Thrust (lbs) Boat Size (ft)
12-volt 30-40 Less than 16
24-volt 80-100 16-19
36-volt 101-112 20 or more

As shown in the table, the appropriate voltage for your boat depends on factors such as motor thrust and boat size. It’s essential to select a battery with the right voltage to ensure optimal performance and longevity.

It’s worth noting that higher voltage batteries tend to be more expensive. However, the benefits of a higher voltage battery, such as increased motor thrust and runtime, may outweigh the additional cost.

When selecting your battery voltage, it’s important to consider the charging requirements as well. Higher voltage batteries require specific charging equipment for proper charging, which may add to the overall cost and complexity of your battery setup.

Battery Weight and Size

When it comes to selecting a marine battery for your trolling motor, both weight and size are crucial considerations. The weight and size of the battery can affect the overall balance and performance of your boat. Additionally, space constraints may limit the size of the battery you can use.

To ensure optimal performance and avoid any balance issues, it’s important to choose a battery that is both appropriately sized and weighted for your needs. Keep in mind that a heavier battery can also affect the speed and performance of your boat.

One way to determine the ideal size and weight for your battery is to consider the available space on your boat. If you have limited space, a smaller battery may be necessary. However, if space is not an issue, you can opt for a larger battery that offers greater capacity and runtime.

Battery Type Weight Size
Deep Cycle Battery 50-150 lbs 6-16 inches in height, 10-20 inches in length
Starting Battery 25-50 lbs 6-8 inches in height, 8-12 inches in length
AGM Battery 30-75 lbs 6-10 inches in height, 9-15 inches in length

As seen in the table above, deep cycle batteries tend to be the heaviest and largest, while starting batteries are the lightest and smallest. AGM batteries fall in between the two.

Ultimately, the weight and size of your battery will depend on your specific needs and the available space on your boat. Consider these factors carefully before making your final decision.

Battery Maintenance and Longevity

Proper maintenance and charging practices are essential for maximizing the lifespan of your marine battery and ensuring its reliable performance. Here are some tips for taking care of your battery:

  • Always follow the manufacturer’s instructions for charging and maintaining your battery.
  • Make sure the battery terminals are clean and free of corrosion. Use a wire brush or a battery terminal cleaner to remove any buildup.
  • Check the water level in flooded lead-acid batteries regularly and add distilled water as needed to keep the plates covered.
  • Avoid over-discharging your battery, as this can damage the cells and shorten its lifespan. Use a battery monitor or voltmeter to keep track of the charge level.
  • Store your battery in a cool, dry place and keep it fully charged when not in use.
  • Consider using a battery maintenance device or charger that automatically maintains the charge level and condition of the battery, especially if you store your boat for extended periods of time.

By following these practices, you can extend the lifespan of your marine battery and avoid the need for frequent replacements. On average, a well-maintained deep cycle battery can last between 4-8 years, while a starting battery may last 3-6 years.

It’s also important to note that as a battery ages, its capacity may decrease, which can affect the runtime of your trolling motor. To ensure optimal performance, you may need to periodically test your battery’s capacity or consider replacing it when it starts to show signs of significant wear and tear.


Choosing the right size marine battery for your trolling motor is essential for optimal performance and longer battery life. By taking into account factors such as trolling motor power requirements, battery types, capacity, voltage, weight, and maintenance, you can find the perfect marine battery for your specific boating needs.

Final Thoughts

It’s important to remember that investing in a high-quality marine battery will save you money and prevent frustration over time. By selecting the right battery size and type, you can enjoy extended runtime, a smoother boating experience, and increased longevity for your battery. Do not compromise on quality, and always follow recommended charging and maintenance practices to ensure the best performance and lifespan for your marine battery.

Stay Safe on the Water

Always prioritize safety when boating. Remember to check your marine battery regularly, wear life jackets, and follow boating laws and regulations. With the right marine battery and safe boating practices, you can enjoy a stress-free and enjoyable time on the water.

Richard Dodds

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