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Welche Größe Batterie für Marine Boot?

What size battery for marine boat?

, by Sally Zhuang, 17 min reading time

Choosing the right marine battery size is an important decision for boaters. Whether you're a first-time boat owner or an experienced sailor, understanding the factors involved in selecting the right size marine battery is critical to optimal performance. This article will provide you with 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 designed to withstand the challenges of a maritime environment such as vibration, shock and constant contact with water. Marine batteries are usually deep cycle batteries, i.e. H. they can be discharged and recharged repeatedly without losing their capacity. They provide the energy necessary to start the boat engine, operate electrical systems and operate additional devices on board.

What role does the size of the naval battery play?

The size of the 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 power needs when you're on the water.

The size of a marine battery is typically 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 given period of time.

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 performance requirements. For example, larger boats typically require larger batteries to accommodate their electrical systems and devices.
Power Requirements: Determine the electrical devices and systems on board that require power. This includes electronics, lighting, pumps, devices and other accessories. Calculate the total power consumption to determine the required battery size.
Climatic Conditions: Extreme temperatures, both hot and cold, can affect the performance and lifespan of a battery. Depending on the climate in which you operate your boat, you will need to choose a battery with an appropriate cold cranking capacity (CCA) or reserve capacity (RC) to ensure reliable performance in those conditions.


Careful consideration of boat type, power requirements and climatic conditions will help you select the right marine battery size to meet your specific needs and ensure reliable power on the water.

How do you calculate the power requirements of your boat?

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

  1. Make a checklist of all electrical devices on your boat, including lights, bilge pumps, trolling motors and other devices.
  2. Determine the power consumption of each device. This value is usually specified in the boat's manufacturer's manual in amps. If not available, use a multimeter to measure the amps.
  3. Note the runtime for each device. This is the length of time you want to use each device during a charging cycle.
  4. Calculate the amp-hour rating of each device by multiplying the amp consumption by the operating time. For example, if a light bulb uses 1 amp and runs 6 hours a day, the power consumption is 6 amp hours (Ah).
  5. Add the amp-hour ratings of all devices to determine the boat's total power consumption.
  6. Consider adding a margin of 20 to 30% to account for losses and temporarily higher power requirements.
  7. Use total power consumption to determine the amp-hour battery rating that meets your needs. Buy a battery with this Ah rating as the batteries on the market are sorted 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 have the wattage of each device. To find the amp-hour rating, divide the total wattage by the voltage of the boat 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. The total wattage would be:

Total power = 20 + 10 + 40 + 10 + 40 + 30 = 150 W
If you plan to use these devices for six hours on a single charge, the watt-hour rating is:
Watt hours = 150 W x 6 hours = 900 Wh
To determine the amp-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, a 12V 100Ah battery would be suitable.

Types of marine batteries based on chemistry

There are different types of marine batteries based on their chemistry. Here are some common ones:

  1. Lead-acid battery

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

  1. AGM battery (Absorbent Glass Mat)

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

  1. Lithium-ion battery (LiFePO4)

 Lithium-ion batteries are the most advanced and expensive option. For marine applications, the type of lithium battery is LiFePO4 battery. They offer incredible energy density and long cycle life. Li-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 provide a constant output voltage throughout the 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 LiFePO4 batteries are 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. You can find an explanation of these advantages here:

Weight: LiFePO4 lithium batteries are significantly lighter than conventional lead-acid batteries. This weight reduction can be critical for marine applications as it allows for greater fuel efficiency and more accessible placement in the boat. The lower weight also helps improve the overall performance of the ship, particularly in terms of speed and maneuverability.
Lifespan: 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 degrades. The high-quality LiFePO4 batteries like Power Queen have a lifespan of up to 4000-15000, while lead-acid batteries only have a lifespan of 300-500. This extended lifespan is beneficial for marine applications where reliability and durability are critical, as it reduces the need for frequent battery replacement.
Depth of discharge: LiFePO4 lithium batteries can be further discharged without causing damage. They can typically be discharged up 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, which makes them superior compared to other battery types such as. b Lead-acid batteries can be charged much faster. This faster loading capability is beneficial for marine vessels as it reduces downtime and allows for faster 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 provides more space for other important equipment on board.


Although their initial cost is higher than other types of batteries, their extremely long lifespan and other advantages make them a worthwhile investment.

Learn more about the customer reviews for Power Queen.

The standard size of Ship Battery

The standard size of marine batteries may 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 amp hours (Ah). Group 27 and 31 batteries are also commonly used in marine applications and offer higher capacities of around 90-105 Ah respectively. 95-125Ah.

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


Size (inches)


10.25 x 6,81 x 8,88


10,75 x 6,81 x 8,88


10,25 x 6.81 x 9.38


10,25 x 6.81 x 9


10.25 x 6.81 x 9.75


12.06 x 6.81 x 8.88


12.5 x 6.81 x 8.94


11.75 x 6.81 x 9.25


13 x 6.72 x 9.44


20.75 x 11.13 x 9.88

Different types of trolling motor

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

Rear mounted trolling motor

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

Bow-mounted trolling motor

Bow mount trolling motors are mounted on the front (bow) of the boat. They offer better maneuverability and control, especially in wind and rough water conditions. These motors usually have features like GPS integration and wireless control.

Motor Mounted Trolling Motor

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

Hand controlled trolling motor

These trolling motors have a tiller handle that allows you to control the motor manually. They are generally cheaper, easier to use and suitable for smaller boats or anglers who prefer a hands-on approach.

Foot controlled trolling motor

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

Remote controlled trolling motor

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

Choosing the type of trolling motor depends on factors such as boat size, fishing style, water conditions and personal preference. It's 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 sufficient continuous discharge current to accommodate the maximum amp draw of the trolling motor. If you experience problems with your trolling motor when using lithium batteries, it is important to ensure that there is enough continuous power available to allow the motor to operate at its maximum current draw. The table below shows the maximum current draw based on motor thrust.

Trolling Motor Thrust/Model

Required continuous discharge current



40 lb., 45 lb


50 lb., 55 lb








Engine Mount 101




Engine Mount 160




Talon Shallow Water Anchor


Raptor Shallow Water Anchor



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

Tips for maintenance and care of marine batteries

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

Charging: Follow the manufacturer's instructions to charge your battery. In general, it is recommended to use a smart marine battery charger that monitors and adjusts charging to prevent overcharging.
Storage: If you will not be using your boat for a long time, remove the battery and store it in a cool and dry place. Make sure you charge it regularly to maintain charge and prevent sulfation.
Cleanliness: Keep your battery clean and free of dirt, soot and corrosion. Check the connectors regularly for signs of debris and clean them as necessary with a wire brush or a special battery cleaning solution.
Connections: Ensure battery connections are tight and secure. Loose connections can result in poor performance and shorten battery life.
Electrolyte level (for lead-acid batteries): If you have a lead-acid battery, check the electrolyte level regularly. If they are low, add distilled water to bring them up to the recommended level.
Avoid deep discharging: Avoid deep discharging your battery as this can shorten its lifespan. Charge the battery immediately after use and do not leave it discharged for a long time.
Temperature considerations: Extreme temperatures can affect battery performance. Avoid exposing your battery to excessive heat or cold as this can reduce its capacity and lifespan.
Periodic Inspections: Check your battery regularly 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 follow the manufacturer's guidelines and recommendations for specific care instructions for your marine battery.

Frequently asked questions (FAQs) about marine batteries

  1. Can 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 cause imbalances in the charging and discharging process, resulting in reduced performance and possible damage to the batteries. It is best to maintain consistency in the battery bank to optimize performance and extend the life of your batteries.

  1. What is the most common ship battery size?

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

  1. 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 designed to provide a stable, reliable power source over an extended period of time. This makes them ideal for running electronics, trolling motors and other accessories on a boat.

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