A Comprehensive Guide to Lithium Batteries for Your Boat

When you are launching your boat for a fun day on the water, the experience won’t be complete without sufficient power to keep you cruising throughout the day. Reliable power on a boat is important because it keeps the engine running. Having a quality engine and trusted battery gives you peace of mind in knowing that you won’t get stuck out on the water without a way to move forward.

Not only does reliable boat power allow you to navigate rough waters easily, but you can be sure that you will reach your destination as planned. It’s essential that you always have control over where your boat is moving, especially when you are responsible for the safety of other people on board.

So, before heading to the lake or ocean, it’s a good idea to check your boat’s battery and engine so that you know that everything is working well. If you have an old battery, it might be a good time to upgrade to a newer marine battery. You’ll find four types of marine batteries to choose from, wet cell, gel cell, lead/acid batteries, and lithium batteries.

Different factors will affect your choice when choosing a boat battery, such as your budget, the desired battery lifespan, capacity, and the type of engine. In recent years, lithium batteries have become one of the most popular choices, and it’s easy to see why boaters prefer this technology for their watercraft.




What Is a Lithium Marine Battery?

When you choose lithium technology (known as Li-ion or lithium-ion) for your marine battery, it gives you a rechargeable solution that leverages lithium ions for energy storage. This type of battery is particularly effective for boats that use deep cycling engines.

You’ll have several options when choosing a lithium battery. LiFePO4 (lithium iron phosphate) is gaining in popularity over traditional Li-Ion batteries with a cobalt base because LiFePO4 weighs less, offers a longer lifespan, allows increased power output, and charges faster.

You can expect several benefits from lithium batteries over traditional lead-acid batteries.


Benefits of Lithium Batteries for Boats

Why should you choose a lithium battery for your boat? Here are some of the reasons why these batteries are so popular in the marine industry:

High Energy Density

Usually, lithium-ion batteries are categorized as either high power or high energy. They deliver the power necessary to run the engine and keep you moving on the water. The good news is that this technology is lightweight but still delivers the high-energy response you need.

Improved Longevity

Compared to traditional lead-acid batteries, lithium batteries offer a much longer lifespan. Battery life is based on the discharge-charge cycles of the battery. While specific charge cycles vary depending on your chosen brand, lithium batteries offer five to ten times more cycles than lead-acid batteries.

Lightweight Design

Reducing weight on the boat can be helpful to improve overall performance. Lithium batteries are very lightweight compared to other types of materials. For example, if you are looking for a reliable and lightweight product, the Mealy Marine Longhorn Lithium Battery is a great option to consider.

Full, Reliable Power

When you start using a lithium battery, you can expect to benefit from full power for nearly the entire discharge cycle. No need to worry about only having partial power as the battery begins to lose its charge.

Battery Protection

To prevent battery damage while recharging, lithium batteries use special charging profiles that bring them back to full capacity safely. The batteries can charge rapidly and continue offering efficiency in the power output. When you are shopping for lithium boat batteries, look at compatible chargers you can use for accessories.

Built-In Battery Monitor

Since lithium batteries offer full power at all times, it means that there is no warning when the battery is running out. If the battery runs out of juice, it will stop working immediately. So, boaters need a reliable way of monitoring the available battery power, which is why you should consider a Lithium Blue model that provides a built-in Bluetooth monitor and sends information to an app on your mobile device. The app will show you available power and other relevant details about the battery’s performance.




Understanding Amp Hours and Voltage

When you are in the market to buy a lithium battery, it’s important to learn more about amp hours and voltage so you can pick a battery to match your needs. Here are a few things to consider when comparing amp hours and voltage:

What Is an Amp Hour?

Amp hour (Ah) is an indication of the amount of power available per hour. The measurement indicates the amount of energy charge necessary to allow for 1 ampere of current that will last for one hour. So, the Amp hour rating on a battery helps you determine the capacity of energy storage for deep-cycle or rechargeable lithium batteries.

Usually, lithium-ion batteries have a rating of 3,200 mAh, which means they are able to discharge 3.2 A (3,200 milliamps) in an hour. If you buy a starting battery, it is used faster and is usually rated for 10 hours.

What Is Voltage?

The voltage rating on a battery indicates the pressure coming from the power source for the electrical current and how the current moves through the conducting loop. Voltage is measured in volts and is based on the number of volts per cell.

With lithium-ion batteries, you get a high energy density compared to the size of the battery. Often, the lithium cell voltage is 3.7 volts. But these cells can be used in a battery pack to increase overall voltage.

For example, if you have a 12v lithium LiFePO4 battery that is charged to capacity, it will hold a voltage of around 13.3 – 13.4v overall. This voltage is higher than the 12.6 – 12.7 you can get from an equivalent lead-acid battery. The lithium battery will maintain the same voltage of around 13v when the battery is at 20%, but a lead-acid battery will drop to around 11.8v at 20% capacity.




What to Consider When Buying Lithium Batteries for Boats

Doing some research can ensure that you get a battery with all of the necessary features and power you’ll need for your boat. These are some of the most important factors to consider when you are getting ready to buy a lithium marine battery:

Physical Size and Weight Constraints

Measure the battery storage space on your boat to ensure that the new battery is going to fit. Ideally, you can find a battery with the best capacity and performance that fits the available space. You want to be sure that there is sufficient energy capacity so you can enjoy plenty of time on your boat.

Capacity Requirements for Your Power Needs

How much battery capacity is necessary to keep you on the water? It depends on the size of the boat, the type of engine, and other features you will be using. For example, if you are running things like radios, televisions, or appliances, you need to ensure that your battery can store sufficient power to use these devices.

The amp-hours of the battery will determine how much power you will be able to store. When substantial energy is needed, your best solution is to choose a higher-capacity, deep-cycle battery.

Voltage Compatibility and Configuration

Make sure the battery will be compatible with your boat’s electrical system. As you install the new battery, it’s essential to be sure that the wire configuration works with the type of battery you are using.

Battery Management Systems (BMS) and Safety Features

Not only is a battery management system (BMS) helpful for monitoring the battery’s charge and performance, but it also helps to protect the battery and extend the available lifespan. A BMS comes with safety features to avoid over-charging and over-discharging while reducing the risk of over-current or over-voltage. You can check the BMS app on your smartphone to calculate the available time on your lithium battery.

Charging and Discharging Efficiency

How long will it take to charge the battery? How efficient is the battery during discharging? Check these details since they impact the overall performance of the battery.





Installation and Maintenance of Lithium Batteries

Keep in mind that lithium batteries can be dangerous, especially when they are mishandled. So, always use caution and follow proper installation guidelines when handling the battery. Also, make sure you are only using approved and compatible equipment, including a BMS-controlled charger.

Here are a few more tips to help with lithium battery installation and maintenance:

Monitoring and Balancing Battery Cells

Lithium batteries should always have tools to monitor the levels. Use the monitoring device to check the battery’s charge status regularly. If a battery is approaching the end of the estimated life, be more proactive about monitoring the battery and performance.

There are several things to watch for that will help you determine when your battery needs to be replaced:

  • The battery run time is 80% or less than the original run time.
  • The time required to charge the battery is significantly higher.

When you buy a new lithium battery, pay attention to the run-time when the battery is fully charged. Then, you can use this run-time to compare the performance of your older batteries. Of course, the overall run time of the battery varies depending on what is being powered on the boat and the configuration of the battery.

Charging and Storage

If you are planning to store the battery, it’s best to discharge it to around 50% capacity. Then, every six months, check the battery and charge it back up to 50% capacity.

Stored batteries should be removed from the boat and stored separately. Protect the stored batteries by keeping them in a climate between 41 degrees and 68 degrees Fahrenheit.

Only used approach chargers for the specific type of lithium battery. Also, follow the charging instructions found in the battery’s user manual. If you no longer have the user manual, you can search online for information about your battery.

Safety Measures and Fire Prevention

Follow these safety tips to reduce the risk of a fire, damage, and danger:

  • Keep batteries away from children.
  • If a battery is damaged, then don’t use it.
  • Never puncture, crush, or disassemble a battery.
  • Do not place a battery in water or a fire for disposal.
  • Batteries shouldn’t be exposed to temperatures above 140 degrees Fahrenheit.
  • Don’t short the battery’s external contacts.
  • Avoid battery exposure to excessive vibration or shock.
  • If you can see fluid leaking from a battery, don’t touch the fluid. Dispose of the battery immediately.
  • If battery fluid comes in contact with the eyes, flush with water as quickly as possible. Continue flushing for 15 minutes and avoid rubbing the eyes. Lift the upper and lower eyelids for thorough flushing. Seek medical attention immediately.
  • When transporting a lithium-ion battery, check local, national, and international regulations. For example, there might be limitations or prohibitions on transporting a recalled, damaged, or end-of-life battery.
  • When the battery is fully charged, remove it from the charger. Lithium-ion batteries should always be stored in cool, dry locations.
  • Avoid damage to the battery because damage can affect the battery chemistry and cause it to get hot enough to cause a spontaneous fire. It can be a domino effect, with one battery overheating and catching fire, then spreading to other batteries in the vicinity.




Estimating Lithium Battery Lifespan and Usage

When buying a lithium-ion marine battery, you want to know how long the battery will last in your boat. It’s possible to estimate the usage and lifespan of the battery based on which product you purchase.

How Long Does a Lithium Battery Last?

Typically, the estimated life of a lithium-ion battery is based on whichever occurs first:

  • 3000 – 6000 charge cycles
  • Two to three years

A charge cycle lasts from the battery being fully charged, then fully discharged, and being fully recharged again.

Investing in a lithium deep-cycle battery is usually worth the cost because it will last longer than other marine battery types. When you choose the right model for your boat, this type of battery delivers top-notch results.

Cycle Life of Batteries

Batteries have a cycle life, which is the number of times you can charge and discharge the battery before it stops performing. The depth of the discharge is the amount of storage capacity being used and significantly impacts the cycle life of a lithium-ion battery.

The maximum discharge depth for a lithium-ion battery is 80%. The battery will be damaged if you discharge more than 80%. The general recommendation is that these batteries should be recharged when they reach a DoD of 70% (SoC of 30%).

Factors Affecting Battery Longevity

Several environmental and usage factors can have a direct impact on the longevity of the battery, including:

  • Heat Damage: If a battery is exposed to high heat, then it can cause dangerous conditions, including fire or an explosion. Another risk of heat damage is if the lithium-ion battery is charged to a voltage higher than its rating, which can result in capacity loss and thermal runaway.
  • Cold Temperatures: Cold temperatures can also affect the battery's performance because fluidity can be lost within the inner electrolyte, or the battery can freeze completely. If this happens, then the battery will recharge inefficiently, and the output power will be decreased.
  • Faster Degradation: At higher voltages and temperatures, the battery’s cathode contains a metal covering that can react with the inner electrolyte. As a result, degradation can speed up over time. Energy is wasted because this connection creates oxygen, forming an obstructive film over the cathode.
  • Time Wear and Tear: Similar to other types of batteries, lithium-ion batteries will lose capacity over time. When the battery is used and recharged, it takes a toll on the components within the battery.
  • Frequent Charging: If you charge the battery too frequently without using most of its capacity, then overcharging can have a negative impact on the lifespan of the battery. This same effect can occur if you only recharge the battery to 50% or less of its capacity. Every charging cycle results in battery degradation because it affects the electrodes inside.




 Trolling Motors

Most types of electric trolling motors will perform with any type of marine battery as long as you choose a 12-volt model that is deep-cycle. However, we recommend LiFePO4 (lithium iron phosphate) batteries for the best performance and lifespan.

The power settings on your trolling motor will influence the run time of your battery. Consider the max amp draw when the motor is running and whether you are using a Dakota lithium or lead acid battery. Also, look at the voltage of your motor to ensure the battery will be sufficient. 12V motors are more cost-effective because they are smaller and usually only require one battery. If you need more thrust, a 24V or 36V motor might be installed in your boat, which will likely require multiple batteries.

It's also important to look at the amp draw of your motor. Make sure that your trolling motor has a max amp draw that is lower than the battery’s max amp draw. This measurement is known as the “continuous discharge rate.” You need to make sure that the lithium battery has a max continuous amp discharge that exceeds your motor’s needs.




 Sustainability and Lithium Batteries

Sustainability is something to keep in mind, especially for boat owners worried about their environmental impact. The good news is that lithium-ion batteries can be a responsible choice for protecting the environment.

  • Lower Environmental Impact: When you compare lithium-ion batteries with the alternatives, you’ll see that these batteries have a lower impact overall. Even though lithium-ion batteries contain some toxic chemicals, they don’t have toxic metals such as cadmium or lead. As a result, lithium-ion batteries are easier to recycle compared to other types of batteries.
  • Proper Handling and Disposal: Be proactive about proper handling and disposal of lithium-ion batteries. Keep in mind that these batteries contain chemicals such as nickel, cobalt, and manganese, which can harm the environment when misused. Avoid exposing lithium batteries to water supply systems and keep them away from any water because the chemicals can harm or destroy the aquatic life and ecosystem. Proper disposal is critical for avoiding environmental harm.
  • Potential for Renewable Energy: One benefit of lithium is that it offers a potential foundation that could be used for sustainable renewable energy. Unfortunately, traditional mining methods don’t align with sustainability targets. However, many technological advancements are leading to the possibility of “green lithium” in the future.
  • Recycling for Financial Benefits: Since lithium batteries contain valuable metals, recycling can offer financial benefits.

 Choosing the Ideal Lithium Battery for Your Boat

As you can see, there are many reasons why lithium batteries are the top choice for boat owners. When you invest in a lithium battery and follow the proper maintenance and care instructions, you can be confident that your battery will provide the power you need.

Do a little bit of research about the battery to ensure that it is compatible and powerful enough for your boat’s needs. If you have questions or need professional advice, you can always contact the boating experts for personalized recommendations.