Sportsman Boat Battery: Choosing The Right Size For Your Vessel

When it comes to boats, the battery you need depends on what you want to use your boat for. A deep-cycle battery is used for the trolling motor and electronics, while a starter battery is used to start the engine. The size of the battery you need depends on the engine's size, the type of battery, and what you're using it for. Lithium-ion batteries are a popular choice for boats as they are lightweight and have high energy density, but you can also consider AGM, gel cell, or wet cell batteries. The number of batteries you need depends on your setup, with some boats requiring as few as one, and others requiring up to six.

Deep cycle vs starter battery

Marine batteries are available in three types: deep cycle, starting, and dual-purpose. The type of battery you need depends on your boat's requirements and power configuration.

Deep Cycle vs. Starter Battery

The first thing to consider when deciding what size battery your boat needs is whether the battery will start or operate the boat. A starter battery, also known as a cranking or starting, lighting and ignition (SLI) battery, is designed to provide maximum power for a short duration, usually about 1-3 seconds. It sends power to the engine when the ignition switch is activated. Cranking batteries have many thin plates to increase surface area and make starting a marine vessel as smooth and reliable as possible. However, they are not ideal for continuous discharge or "cyclic" use.

On the other hand, a deep-cycle battery provides continuous power instead of short bursts. It is designed to handle the cyclic demands of deep discharge and can be entirely drained and recharged frequently. Deep-cycle batteries have fewer, thicker plates, allowing them to provide a steady stream of power over a long period. They are ideal for trolling motors and powering electronics like sonar, GPS, and radios.

While starter batteries are primarily used for starting the engine, deep-cycle batteries are used to power the boat after the engine has started. Starter batteries are rated in Cold Cranking Amps (CCA), which measures the battery's cracking ability. In contrast, deep-cycle batteries focus on maximum capacity and are designed for deep discharges.

Dual-Purpose Batteries

As the name suggests, dual-purpose batteries can be used for both starting the engine and providing continuous power for the trolling motor. They are a good option if you want to minimise the number of batteries on your boat. However, they might not always provide the same level of performance as using two separate batteries. Additionally, dual-purpose batteries might not withstand total discharges beyond 50% of usable capacity.

Marine battery types

Marine batteries are designed to handle the unique challenges of the marine environment. They power everything from a boat's engine to electronics and accessories.

There are three main types of marine batteries, each serving a different purpose:

Starting (Cranking) Batteries:

These deliver quick bursts of energy to start the boat's engine. They are not designed for extended, continuous use. Starting batteries typically last 3-4 years with proper maintenance.

Marine Deep-Cycle Batteries:

Deep-cycle batteries are built to provide consistent power over a long period, making them ideal for running electronics, trolling motors, and appliances. They feature thicker plates to withstand repeated discharge and recharge cycles.

Flooded Lead-Acid Batteries:

The most common and cost-effective option, these batteries require regular maintenance, including water level checks and proper ventilation. With good care, they can last 3-5 years.

Absorbed Glass Mat (AGM) Batteries:

These spill-proof, maintenance-free batteries use a fiberglass mat to absorb the electrolyte. AGM batteries offer a longer lifespan of 4-7 years compared to flooded batteries.

Lithium Boat Batteries:

Lithium batteries are increasingly popular due to their lightweight design, high efficiency, and long lifespan. They can last 8-10 years or more. While more expensive upfront, they often provide better long-term value.

Dual-Purpose Batteries:

Dual-purpose batteries combine the cranking power of a starting battery with deep-cycle capability, though they are less efficient than specialised batteries. They typically last 3-5 years, balancing the characteristics of both starting and deep-cycle batteries.

Other Marine Battery Types:

Gel Batteries:

Gel batteries are popular in marine applications due to their unique properties, such as their exceptional cycle life, providing up to three to four times the lifespan of standard AGM or flooded batteries. They also function well in a wide range of temperatures and recharge faster than AGM and flooded batteries.

LiFePO4 (Lithium Iron Phosphate) Batteries:

These batteries are stable, safe, and highly suited to boating applications. They are sealed and can withstand a much higher temperature range without any performance loss. They are more expensive but offer a higher depth of discharge, higher life cycles, a smaller footprint, and faster recharge times than traditional battery types.

Battery weight

Lithium-ion marine batteries are the lightest option available, weighing around 16-32 lbs. They offer a significant weight reduction compared to lead-acid batteries, which typically weigh between 50-120+ lbs. The weight difference is due to the dense lead plates and liquid sulfuric acid used in lead-acid batteries.

The weight of a battery also depends on its capacity, with higher capacity batteries tending to weigh more due to increased materials used. For example, a 100Ah lithium marine battery may weigh around 20-30 lbs, while a lead-acid battery of similar capacity can weigh 60-100 lbs.

When choosing a marine battery, it is essential to consider the balance between weight, performance, and cost. Lithium-ion batteries offer lightweight and high energy density but come at a higher price. Lead-acid batteries, on the other hand, are more affordable but significantly heavier.

By selecting the right battery weight and type, boaters can improve speed, handling, and fuel efficiency, ensuring optimal performance and safety on the water.

Battery life

The battery life of a boat depends on several factors, including the type of battery, its size, and how well it is maintained. Here are some essential considerations for maximising battery life in a 23 Sportsman boat:

Choosing the Right Battery Type

Different types of batteries are available for boats, each with its advantages and disadvantages.

• Lithium-ion batteries are known for their lightweight and high energy density, reducing engine load. They also have a long life cycle, making them a popular choice for those who want a powerful and long-lasting option.
• Absorbent Glass Mat (AGM) batteries feature a fiberglass layer between the electrodes, resulting in a completely sealed design that won't spill. AGM batteries have a longer life and higher power output than traditional lead-acid batteries and are excellent for both starter and deep cycle applications.
• Gel cell batteries contain silica mixed with acid to solidify the liquid, making them stable and versatile. They require little to no maintenance and are ideal for boats as they can withstand jostling without causing problems. However, they have less capacity than AGM batteries and must be recharged correctly to avoid degradation.
• Wet cell batteries are traditional batteries that have been used in various applications. They usually require regular maintenance and are generally safer to charge but less resilient to damage due to their liquid electrolyte.

Sizing Your Battery

When determining the size of your boat battery, consider the following:

• Engine size: The best way to determine the amps needed for your engine is to factor in a single amp for every cubic foot of engine space. Most boat owners will want between 300 and 500 cold cranking amps (CCAs) for starting their boat, based on engine size.
• Deep-cycle vs. starter battery: If you need a battery to start your engine, a starter battery is ideal. On the other hand, a deep-cycle battery is designed to be used for long periods to power electronics and trolling motors.
• Boat requirements: Consider all the electrical components on your boat, such as fish finders, live wells, bait wells, radios, and lights. Ensure your battery has enough capacity to run all these components effectively.
• Weight: Heavier batteries can slow down your boat and increase fuel consumption. Therefore, it is essential to choose a battery that provides sufficient power without adding excessive weight.

Maximising Battery Life

To ensure your boat battery lasts as long as possible:

• Maintain it properly: Keep your battery well-maintained by regularly checking its charge and ensuring it doesn't drop below 50% capacity, as this can cause permanent damage.
• Consider a dedicated battery: If you have multiple electronic components, you may want to consider adding a dedicated battery for high-power devices like fish finders. This will reduce the load on your main battery and help extend its life.
• Use a suitable charger: Different types of batteries require specific chargers. Ensure you use the correct charger for your battery type and follow the manufacturer's instructions for charging to avoid overcharging or undercharging.

Battery charging

Types of Batteries

Before delving into charging procedures, it's crucial to understand the different types of marine batteries:

• Cranking Batteries: These batteries are designed to provide a powerful jolt to start your boat's engine. They are dedicated solely to this purpose and are not meant for powering accessories.
• Deep-Cycle Batteries: Deep-cycle batteries are built to release energy at a slower pace and can be discharged to lower levels for extended periods. They are ideal for powering trolling motors and accessories. Reserve capacity, or the time the battery can carry a load before recharging, is a key factor to consider with this type.
• Dual-Purpose Batteries: As the name suggests, these batteries serve both cranking and deep-cycle functions. However, they don't provide the same level of performance as dedicated cranking or deep-cycle batteries.

Charging Procedures

Now, let's discuss the charging process for your 23-foot sportsman boat battery:

• Charging Materials: The type of charging materials you'll need depends on the construction of your battery. Wet cell or flooded lead-acid batteries are the most common and require routine maintenance. AGM (absorbent glass matting) batteries are maintenance-free, can be mounted in any angle, and don't produce hazardous gases. Gel batteries use a liquid gel that resists overcharging and vibration. Lithium batteries are the latest innovation, offering faster recharging times, lighter weight, and higher efficiency, but they come with a steep price tag.
• Charger Selection: When selecting a charger, you can choose between portable and onboard chargers. Popular brands like Marinco, Optima, West Marine, and NOCO offer portable chargers with alligator clamps. Smart chargers can automatically detect the type of battery, while others require manual settings for gel, lead-acid, and AGM batteries. Onboard chargers, such as those from Promariner, Dual Pro, and Minn Kota, are fully automatic and can distinguish between different battery types. They are more expensive but offer the convenience of charging multiple batteries simultaneously.
• Charging Tips: Always aim to keep your batteries fully charged to prolong their life. Secure them properly to avoid damage during choppy waters. Use stainless-steel nuts with lock washers instead of wing nuts for a secure connection. Carry the appropriate tools to tighten cables or disconnect a battery while on the water. For non-maintenance-free batteries, routinely check water levels. Store your batteries in a climate-controlled space to prevent damage.

By following these guidelines and understanding your battery type, you can ensure your 23-foot sportsman boat battery stays in top condition and provides reliable power during your boating excursions.

Frequently asked questions