What size battery for marine boat?

Choosing the right marine battery size is an important decision for boaters. Whether you're a first-time boat owner or a seasoned sailor, understanding the factors involved in selecting the correct marine battery size is crucial for optimal performance. This article provides valuable insights and practical tips to help you make an informed decision.

What is a ship's battery?

A marine battery is a specially designed deep-cycle battery used to power boats and other watercraft. It is engineered to withstand the challenges of a marine environment, such as vibrations, shocks, and constant contact with water. Marine batteries are typically deep-cycle batteries, meaning they can be repeatedly discharged and recharged without losing capacity. They provide the necessary power to start the boat's engine, operate electrical systems, and run auxiliary equipment on board.

What role does the size of the marine battery play?

The size of your marine battery is important because it directly affects the performance and reliability of your boat's electrical system. Choosing the right size marine battery ensures you have enough power to start your engine, run your electronics, and meet your electrical needs while you're on the water.

The size of a marine battery is generally determined by its physical dimensions, weight, and electrical capacity. A battery's electrical capacity is measured in ampere-hours (Ah) and refers to the total amount of charge it can deliver over a specific period.

How to choose the size of a marine battery?

When choosing the size of a marine battery, you need to consider several factors:

• Boat type and size:Different boat types and sizes have different power requirements. Larger boats, for example, generally need larger batteries to power their electrical systems and equipment.
• Power consumption: Identify the electrical devices and systems on board that require power. This includes electronics, lighting, pumps, appliances, and other accessories. Calculate the total power consumption to determine the required battery size.
• Climatic conditions:Extreme temperatures, both hot and cold, can affect a battery's performance and lifespan. Depending on the climate in which you operate your boat, you need to choose a battery with adequate cold cranking amps (CCA) or reserve capacity (RC) to ensure reliable performance under these conditions.

By carefully considering the boat type, performance requirements and climatic conditions, you can select the right marine battery size to meet your specific needs and ensure a reliable power supply on the water.

How do you calculate your boat's electricity requirements?

Here are some steps you can take to calculate the boat's power requirements:

1. Create a checklist of all electrical equipment on your boat, including lights, bilge pumps, trolling motors and other devices.
2. Determine the power consumption of each device. This value is usually given in the boat's manufacturer's manual in amperes. If this is unavailable, use a multimeter to measure the amperage.
3. Note the battery life for each device.This is the duration you want to use each device during a charging cycle.
4. Calculate the ampere-hour rating of each device by multiplying its amperage consumption by its operating time. For example, if a light bulb consumes 1 ampere and is used for 6 hours a day, its power consumption is 6 ampere-hours (Ah).
5. Add up the amp-hour ratings of all devices to determine the total power consumption of the boat.
6. Consider adding a margin of 20 to 30% to account for losses and temporarily higher power demands.
7. Determine the amp-hour battery capacity that meets your needs based on your total power consumption. Purchase a battery with this Ah rating, as batteries on the market are categorized by amp-hours.

Another way to express the same meaning is to calculate the total wattage of the electrical load. This is useful if you know the wattage of each device. To find the ampere-hour rating, divide the total wattage by the voltage of the boat's electrical system.

For example, let's say you have a 20W light, a 10W navigation system, a 40W autopilot system, a 10W radar, 40W navigation lights, and a 30W water purifier.

1. The total wattage would be:

   Total power = 20 + 10 + 40 + 10 + 40 + 30 = 150 W

2. If you plan to use these devices for six hours on a single charge, The watt-hour figure is:

   Watt-hours = 150 W x 6 hours = 900 Wh

3. To determine the ampere-hour rating for a 12V boat system, Divide the watt-hours by the voltage:

   Ah = 900 Wh ÷ 12V = 75 Ah

Therefore, the battery you need for the boat is at least 12V 75Ah. 12V 100Ah battery would be suitable.

Types of marine batteries based on chemistry

There are different types of marine batteries due to their chemical composition. Here are some common ones:

1. Lead-acid battery

Lead-acid batteries are the most common and cost-effective type of marine battery. They have a long history of use and come in two types: flooded and sealed. Flooded lead-acid batteries require regular maintenance, including checking the electrolyte level and topping up with distilled water. Sealed lead-acid batteries, also known as valve-regulated lead-acid batteries (VRLA), are maintenance-free.

2. AGM battery (Absorbent Glass Mat)

AGM batteries are an advanced type of lead-acid battery. They use glass mat separators to retain the electrolyte, resulting in a leak-proof design. Compared to flooded lead-acid batteries, AGM batteries have a longer lifespan and require minimal maintenance. They also have lower internal resistance, allowing for faster charging and discharging.

3. Lithium-ion battery (LiFePO4)

Lithium-ion batteries are the most advanced and expensive option. For marine applications, the type of lithium battery used is typically LiFePO4. They offer incredible energy density and a long cycle life. Lithium-ion batteries are much lighter and more compact than lead-acid batteries, making them ideal for applications where weight and space are critical. They also deliver a constant output voltage throughout the entire discharge cycle.

These are just a few examples of marine battery types, based on their chemistry. Each type has its own advantages and considerations.Therefore, it is important to assess your specific needs and budget before making a decision.

Why are LiFePO4 batteries the most recommended?

LiFePO4 lithium batteries are often considered the best option for marine boats because they offer several advantages in terms of weight, lifespan, and other important factors. Here is an explanation of these advantages:

• Weight:LiFePO4 lithium batteries are significantly lighter than conventional lead-acid batteries. This weight reduction can be crucial for marine applications, as it allows for greater fuel efficiency and more accessible placement on board. The reduced weight also contributes to improved overall vessel performance, particularly in terms of speed and maneuverability.
• Life:LiFePO4 lithium batteries tend to have a longer lifespan compared to other battery types. They can withstand a higher number of charge cycles, meaning they can be charged and discharged more often before their performance deteriorates. High-quality LiFePO4 batteries like Power Queen have a lifespan of up to 4,000–15,000 cycles, while lead-acid batteries only last 300–500 cycles. This extended lifespan is advantageous for marine applications where reliability and durability are critical, as it reduces the need for frequent battery replacements.
• Discharge depth:LiFePO4 lithium batteries can be discharged further without sustaining damage. They can typically be discharged to 80–90% of their capacity without negatively impacting their overall lifespan or efficiency. This deeper discharge capability provides more usable capacity for marine applications and enables longer operating times on a single charge.
• Charging efficiency:LiFePO4 lithium batteries have excellent charging efficiency, allowing them to be charged much faster compared to other battery types, such as lead-acid batteries. This faster charging capability is advantageous for marine vessels, as it reduces downtime and enables quicker turnaround times between trips.
• Size and space efficiency:Lithium-ion batteries have a higher energy density, meaning they can store more energy in a smaller package compared to other battery chemistries. This compact size allows for greater flexibility in boat design and frees up more space for other essential equipment on board.

Although their purchase costs are higher than those of other battery types, they are still a worthwhile investment due to their extremely long lifespan and other advantages.

Learn more about Customer reviews for Power Queen.

The standard size of a ship's battery

The standard size of marine batteries can vary depending on the specific application and boat size. However, the most common marine battery size is Group 24, which typically has a capacity of around 75–85 ampere-hours (Ah). Group 27 and 31 batteries are also commonly used in marine applications and offer higher capacities of approximately 90–105 Ah and 95–125 Ah, respectively.

These sizes are typically available in various battery chemistries such as lead-acid, AGM, and lithium-ion. Larger boats may require multiple batteries or batteries with higher capacity to meet their power needs.It is important to consider factors such as electrical load requirements, expected operating time, and available space before selecting the appropriate battery size for your specific marine application.

Group	Size (inches)
24	10.25 x 6,81 x 8,88
24F	10,75 x 6,81 x 8,88
24H	10,25 x 6.81 x 9.38
24R	10,25 x 6.81 x 9
24T	10.25 x 6.81 x 9.75
27	12.06 x 6.81 x 8.88
27F	12.5 x 6.81 x 8.94
27H	11.75 x 6.81 x 9.25
31	13 x 6.72 x 9.44
8D	20.75 x 11.13 x 9.88

Different types of trolling motors

There are various types of trolling motors you can use for your boat. Here are some of the most common types:

1.Rear mounted trolling motor

This is the most popular type of trolling motor and is mounted on the transom of the boat. It is easy to install and can be adjusted to various angles. Transom-mounted motors are versatile and suitable for different boat sizes and types.

2.Bow-mounted trolling motor

Bow-mounted trolling motors are mounted at the front (bow) of the boat. They offer improved maneuverability and control, especially in windy and rough water conditions. These motors typically include features such as GPS integration and wireless control.

3. Motor-mounted trolling motor

Motor-mounted trolling motors, also called auxiliary motors, are mounted directly onto the cavitation plate of an outboard or inboard engine. They are ideal for larger boats and can be used as the primary drive or as a supplement to the main engine.

4. Hand-operated trolling motor

These trolling motors feature a tiller handle, allowing you to steer the motor manually. They are generally cheaper, more user-friendly, and suitable for smaller boats or anglers who prefer a practical approach.

5. Foot-operated trolling motor

Foot-operated motors are controlled via a pedal system, allowing for hands-free operation. They offer precise control and are popular with anglers who want to concentrate on fishing without constantly having to adjust the motor.

6. Remote-controlled trolling motor

These trolling motors come with a wireless remote control, allowing you to operate the motor from anywhere on your boat. Remote-controlled motors offer convenience and flexibility, especially for anglers who want to move around while operating the motor.

The choice of trolling motor type depends on factors such as boat size, fishing style, water conditions and personal preferences.It is important to consider your specific needs and the features that will enhance your boating and fishing experience.

Recommended size for trolling motor

The amp-hour rating of a battery directly affects the runtime it can provide. It is important to select a lithium battery with a sufficient continuous discharge current to meet the maximum amperage draw of the trolling motor. If you experience problems with your trolling motor when using lithium batteries, you must ensure that enough continuous current is available to operate the motor at its maximum current draw. The table below shows the maximum current draw based on motor thrust.

Trolling engine thrust/model	Required continuous discharge current
30 lb	30
40 lb., 45 lb	42
50 lb., 55 lb	50
70 lb	42
80 lb	56
101 lb	46
Engine Mount 101	50
112 lb	52
Engine Mount 160	116
E-drive	40
Talon Shallow Water Anchor	30
Raptor Shallow Water Anchor	70

Note: A starter battery is not suitable for use with an electric trolling motor.

Thrust range	LiFePO4 battery capacity	Recommended battery
30 to 55 pounds	50-100 Ah	Power Queen 12V 100Ah Power Queen 12V 100Ah Mini
55 to 80 pounds	100-150 Ah	Power Queen 12V 200Ah
80 to 100 pounds	150-200 Ah	Power Queen 12V 300Ah
200 to 300 pounds	200-300 Ah	Power Queen 12V 410Ah

Read more about the recommended battery system for trolling motors.

Tips for the maintenance and care of ship batteries

Proper maintenance and care are crucial to ensuring the longevity and performance of your marine battery.Here are some tips to help you keep your battery in good condition:

• Load:Follow the manufacturer's instructions to charge your battery. Generally, the use of a smart marine battery charger is recommended, as it monitors and adjusts the charging process to prevent overcharging.
• Storage: If you are not using your boat for an extended period, remove the battery and store it in a cool, dry place. Make sure to charge it regularly to maintain its charge level and prevent sulfation.
• Cleanliness: Keep your battery clean and free of dirt, soot, and corrosion. Regularly check the terminals for signs of deposits and clean them with a wire brush or a special battery cleaning solution if necessary.
• Connections:Ensure that the battery connections are tight and secure. Loose connections can lead to poor performance and shorten battery life.
• Electrolyte level (in lead-acid batteries): If you have a lead-acid battery, check the electrolyte level regularly. If it is low, add distilled water to bring it up to the recommended level.
• Avoid deep discharges: Avoid deep discharging your battery, as this can shorten its lifespan. Charge the battery immediately after use and do not leave it in a discharged state for extended periods.
• Temperature aspects: Extreme temperatures can affect battery performance. Avoid exposing your battery to excessive heat or cold, as this can reduce its capacity and lifespan.
• Regular inspections:Regularly check your battery for signs of damage or wear. If you notice bulges, cracks, or other abnormalities, it may be time to replace the battery.

Remember to always refer to the manufacturer's guidelines and recommendations for specific care instructions for your marine battery.

Frequently Asked Questions (FAQs) about ship batteries

1. Can the battery sizes be mixed on the boat?

   It is generally not recommended to mix battery sizes on a boat. It is best to have batteries of the same size, type, and age in the same battery bank. Mixing different sizes or capacities can lead to imbalances in the charging and discharging process, resulting in reduced performance and potentially battery damage. Maintaining consistency within the battery bank is best for optimizing performance and extending the lifespan of your batteries.

2. What is the most common size of marine battery?

   The most common marine battery size is typically Group 24. Group 24 batteries are widely used in various marine applications, including as starter batteries for smaller boats and as multi-purpose batteries for boats with moderate power demands. These batteries offer a good balance of size, capacity, and affordability, making them a popular choice for many boaters. However, it's important to note that the appropriate battery size depends on individual power requirements. Therefore, it's always best to consult the manufacturer's recommendations for your specific setup.

3. Does a boat need a deep-cycle battery?

   Deep-cycle marine batteries are specifically designed for continuous discharge and cyclic use, making them an essential component for boaters. Unlike starter batteries, which are optimized for starting an engine, deep-cycle batteries are engineered to provide a stable and reliable power source over extended periods. This makes them ideal for powering electronics, trolling motors, and other equipment on a boat.