Marine Batteries: Starters, Deep Cycle, and Dual Purpose

Introduction

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In the world of boating and marine adventures, a reliable and efficient power source is the backbone of any successful voyage. Marine batteries play a crucial role in providing electrical energy for a wide range of applications from starting engines to powering onboard electronics. In this blog post, we will explore the basics of marine batteries, and how to choose the right battery for your application.

What is a marine battery?

Marine batteries are a type of battery designed to provide power for marine applications, such as boats, yachts, and other watercrafts. They have three types based on their jobs: starting batteries, deep cycle batteries, and dual-purpose. The starting battery ensures reliable engine ignition, while the deep cycle battery provides a steady power supply for extended use of electrical systems and appliances on board. Dual-purpose marine batteries are designed to serve both starting and deep cycle purposes.

Starter Batteries

Marine starter batteries, also known as marine cranking batteries or marine engine start batteries, are a type of lead-acid battery specifically designed for the purpose of starting boat engines. They are engineered to deliver high-cranking amps (CA) and cold-cranking amps (CCA) for quick engine ignition.

Cranking amps is a measure of a battery’s ability to deliver a burst of power at 32°F (0°C) for 30 seconds while maintaining a minimum voltage. CA is commonly used to assess the battery’s starting power in relatively mild or moderate climates, where the temperatures are not extremely cold.

Cold Cranking Amps, on the other hand, are a more stringent measure of a battery’s starting power. It is defined as the maximum current a battery can deliver at 0°F (-18°C) for 30 seconds while maintaining a minimum voltage. CCA is crucial for cold weather starting, where the engine oil may be thicker, making it more challenging for the engine to turn over. For more information on cold cranking amps check out our blog post, “What are CCAs”.

Deep Cycle Batteries

Deep-cycle marine batteries are specifically designed to provide a steady and sustained power output over an extended period, making them ideal for applications that require continuous power delivery. Unlike starting batteries that are optimized for short bursts of high current to start engines, deep-cycle marine batteries are built with thicker lead plates to withstand repetitive deep discharging and recharging without damage.

These batteries are commonly used to power various electrical systems and appliances on boats, such as lights, trolling motors, fish finders, radios, and refrigerators. Deep-cycle marine batteries are crucial for boating activities that demand a reliable and long-lasting power source, ensuring that boaters can enjoy their time on the water without worrying about power interruptions.

Dual Purpose

Dual-purpose batteries aim to provide a balance between the characteristics of cranking (starting) batteries and deep-cycle batteries. These batteries are engineered to deliver the high burst of power needed to start an engine while also being capable of providing a moderate amount of sustained power for running onboard electronics and accessories.

Many deep-cycle marine batteries on the market today are designed with dual-purpose capability. If you have a smaller boat with a less demanding engine, a quality dual-purpose deep-cycle marine battery might be sufficient to start the engine and power accessories. However, for larger boats with more powerful engines or if you have a lot of onboard electronics and accessories, it’s generally recommended to use a dedicated cranking battery for engine starting and a separate deep cycle battery (or batteries) for accessory power.

How are marine batteries different?

Marine batteries have specific characteristics to withstand the unique challenges of the marine environment, such as constant motion, vibration, and exposure to moisture. They are engineered to combat the vibrations and shocks experienced on boats, especially during rough waters or high-speed travel. This is achieved through improved construction and internal components that secure the battery’s plates and prevent damage from vibration. Due to the potential risks associated with marine environments, marine batteries often have additional safety features. For example, some marine batteries are equipped with spark arrestors to prevent explosions in case of an accidental spark during charging.

Additionally, marine batteries are designed to resist corrosion caused by exposure to saltwater and other corrosive elements found in the marine environment. They typically use materials that are more resistant to corrosion, such as lead alloys. Lastly, marine batteries can come with different terminal types and sizes to accommodate various boat setups and electrical systems. For example, some marine batteries have specialized terminal designs to prevent accidental short circuits or to enable quick-connect features.

What size marine battery do I need?

Marine batteries come in various sizes to accommodate different power requirements and fit specific battery compartments on boats. The size of a marine battery is typically expressed in terms of group sizes, with numbers or letters used to identify the different sizes. Larger group sizes generally offer higher capacity and are suitable for applications with higher power demands, such as powering multiple electronics and accessories. Smaller group sizes are ideal for smaller boats or those with lower power requirements. Choosing the right marine battery size ensures optimal performance, efficient space utilization, and reliable power supply for various applications during boating adventures. You can learn more about marine battery sizing here.

Lithium or Lead Acid?

Lithium batteries offer a host of significant advantages that make them an excellent choice for marine applications. One of their key strengths lies in their exceptional energy density, allowing them to store more power in a smaller and lighter package compared to traditional lead-acid batteries. This weight reduction not only enhances boat performance but also optimizes fuel efficiency and handling. Another prominent advantage is their long cycle life, enduring thousands of charge and discharge cycles, far outlasting lead-acid batteries. This longevity ensures boaters can rely on lithium batteries for extended periods without frequent replacements, providing a more reliable power source for their marine adventures.

Additionally, lithium batteries boast a higher charge efficiency, meaning they can absorb and store energy more efficiently during charging, reducing downtime and maximizing time spent on the water. Furthermore, lithium batteries, despite their higher upfront cost, prove to be a more economical and efficient choice in the long run. You can learn more about the benefits of lithium here.

While lithium batteries are considered the optimal choice for marine applications, lead-acid batteries offer their own set of advantages. They have a lower upfront cost, providing a budget-friendly option for boaters looking to power their vessels without breaking the bank. Another advantage is their safety and reliability. They are well-established, as they have been used in the marine industry for many years, building a proven track record. Lastly, lead acid batteries are well-suited for starting applications, as they have no over-current protections. Check out Battery Universities’ article, “Can the Lead-Acid Battery Compete in Modern Times?’ for more advantages of lead acid.

How long do marine batteries last?

The lifespan of marine batteries varies depending on their type. Starting batteries, designed for quick bursts of high current, typically last around 3 to 5 years. Deep cycle batteries, engineered for sustained power delivery, can endure between 2 to 4 years when well-maintained. Lithium marine batteries, on the other hand, can last 10 to 15 years!

Frequent use and deep discharging can put additional stress on lead acid marine batteries, leading to faster wear and shorter lifespans. Properly managing discharge levels and avoiding over-discharging can significantly extend battery life. Additionally, correct charging practices are crucial for battery longevity. Overcharging or undercharging can harm marine batteries, reducing their service life. Utilizing smart chargers that deliver the right charging voltage and current based on the battery’s capacity and state of charge helps preserve the battery’s health. Lastly, regular maintenance, including cleaning terminals and protecting batteries from extreme conditions, is essential to extend their life in this challenging setting.

How should a marine battery be stored?

Choose a storage location that is cool, dry, and well-ventilated. Avoid exposing the battery to extreme temperatures or direct sunlight, as both can accelerate the battery’s degradation. A stable storage environment helps preserve the battery’s performance and protects it from unnecessary wear. Before storing the marine battery charge the battery according to the manufacturer’s recommendation. To learn more, check out Battery Universities’ article, “How to Store Batteries”.

Conclusion

In conclusion, understanding the basics of marine batteries is essential for making an informed decision that aligns with your boating needs. Marine batteries are built with unique features to endure the harsh environment at sea. Both lithium and lead acid battery types have their advantages and considerations for marine applications. When choosing between the two, consider factors such as power requirements, available space, weight capacity, and budget constraints. Careful battery selection ensures that your marine adventures are powered efficiently and reliably, allowing you to embark on memorable journeys with peace of mind.

Whether you're a seasoned boater or planning your maiden voyage, understanding your marine battery is essential to boating. A reliable marine battery is the heart of your boat's electrical system, providing the power you need to start the engine, run electronics, and keep everything functioning while you're on the water.

Contact us to discuss your requirements of marine battery pack. Our experienced sales team can help you identify the options that best suit your needs.

Boat Maintenance Guide

What Is A Marine Battery?

Marine batteries are specially designed to handle the unique challenges of the marine environment. They power everything from your 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.

Marine Deep-Cycle Batteries

A deep-cycle battery is built to provide consistent power over a long period, and it is ideal for running electronics, trolling motors, and appliances.

Dual-Purpose Batteries

As the name suggests, dual-purpose batteries combine the cranking power of a starting battery with the deep-cycle capability, though they are less efficient than specialized batteries.

Deep-Cycle vs. Cranking Batteries: What's the Difference?

A common point of confusion is the difference between deep-cycle and cranking batteries.

Cranking (Starting) Batteries are designed to quickly deliver a large amount of power to start your engine. Once the engine runs, the alternator takes over, and the battery isn't needed for long-term power.

Deep-Cycle Batteries are engineered for steady, sustained energy output, which is ideal for electronics like fish finders, GPS systems, and onboard appliances that require a continuous power supply over long periods.

If your boat requires both functions, consider a dual-purpose battery, although it won't perform each task as well as the specialized versions.

Read Next: How to Winterize Your Boat

How to Choose the Right Marine Battery for Your Needs

Choosing the right battery depends on your boat's requirements and how you use it. Here are a few factors to consider:

1. Boat Size and Power Needs: A small boat with minimal electronics will have different power needs than a large vessel with sophisticated systems.
2. Battery Types: If your boat demands high bursts of power for starting and long periods of power for running electronics, you may need separate starting and deep-cycle batteries or a dual-purpose battery.
3. Reserve Capacity: Look for a battery with enough reserve capacity (RC) to power your systems if your alternator fails. RC measures how long a battery can provide 25 amps of power before dropping below 10.5 volts.
4. Cold Cranking Amps (CCA) and Marine Cranking Amps (MCA): These ratings indicate how well a battery can crank an engine in low-temperature conditions.

Understanding Marine Battery Numbers and Ratings

When selecting a marine battery, you'll come across various numbers that represent its performance:

• Cold Cranking Amps (CCA) vs. Marine Cranking Amps (MCA): Again, CCA refers to how many amps a battery can deliver in cold temperatures, while MCA refers to its cranking power in marine environments, which are usually warmer. Most boaters should focus on MCA.
• Amp-Hours (Ah): This number measures the battery's capacity. It tells you how long the battery can deliver a certain amount of current. The higher the Ah rating, the longer the battery can provide power.
• Reserve Capacity (RC): RC is how long the battery can supply power before it needs to be recharged. It's a critical number to look at if you're running electronics off the battery.

Charging a Marine Battery: Best Practices

The environment is hard on your marine battery - everyday heat can considerably shorten battery life in warmer climates. In areas with cold weather that calls for winter storage, a battery that is not kept charged can freeze in colder temperatures. 

Proper charging is essential for extending the life of your marine battery. Here's how to keep your battery in peak condition:

• Only use a charger designed for marine batteries. Overcharging or undercharging can shorten battery life.
• Different types of batteries require different charging voltages. For example, a 12-volt deep-cycle battery should be charged to around 14.4-14.8 volts.
• Consider using a trickle charger to maintain battery health over long periods when your boat is not in use. It's best to keep batteries on a regulated "trickle" charger to hold a charge while not in use. 

How to Maintain and Extend the Life of Your Marine Battery

Here are some Tips for Avoiding Battery Problems and how to keep your battery in excellent condition:

• Frequently check the battery terminal connections to ensure they are snug and corrosion-free. Check for cracks, bulges, or leaks. Any signs of damage should be corrected as soon as possible.
• Corrosion around the terminals can prevent your battery from functioning correctly. Clean the terminals regularly using a mixture of baking soda and water.
• High temperatures can shorten the lifespan of your battery. Keep it cool and out of direct sunlight when possible.
• Vibration can damage your battery. Secure the marine battery with a good battery box or battery tray, which should have a base that is screwed or bolted to the boat and either a rigid bracket or a locking strap to hold it to the base. You don't want the battery banging around in rough water.
• If you use the boat infrequently, use a maintenance-type battery charger to keep the battery fully charged between outings.
• Before off-season storage, completely charge the batteries, then disconnect the terminals so nothing can draw the battery down. If there's power available at your storage site, keep the batteries on a battery maintainer/charger through the off-season to continually maintain your batteries. Otherwise, remove the batteries from the boat and store them where they can be connected to a maintenance charger.
• Install a cover or "boot" over the top of the positive battery terminal if one was not installed by the boat builder, even if the battery is in a covered box. The boot prevents sparks and arcing and possible explosion if, for instance, a tool is dropped on the terminal.

Storing Marine Batteries During the Off-Season

If you don't use your boat year-round, storing your battery correctly during the off-season is essential. Always fully charge your battery before storing it. A partially charged battery is more likely to freeze. Store your battery in a cool location to prevent overheating or freezing.

Check the battery's voltage regularly during storage and recharge as necessary to prevent deep discharge.

Troubleshooting Common Marine Battery Issues

If you run into problems, here are some common issues to watch out for:

Battery Won't Hold Charge

This could be due to sulfation, where lead sulfate crystals build up and reduce capacity. Regularly charging your battery can help prevent this.

Rapid Drain

If your battery drains quickly, you may have a parasitic load, where some device is drawing power even when the boat is off.

Signs of Aging

As batteries age, they hold less charge. If your battery is several years old, it may need replacing.

When and How to Replace Your Marine Battery

Marine batteries typically last 3-5 years, but this can vary depending on use and maintenance. Common signs that it's time for a replacement include:

• Slow Cranking: If your engine takes longer than usual to start, it may be time for a new battery.
• Swelling or Leaking: Any physical damage is a sign that replacement is necessary.
• Reduced Capacity: If the battery doesn't hold charge like it used to, it's likely reaching the end of its life.

Consult your boat owner's manual or a marine dealer when replacing a marine battery. 

Buy a new marine battery that is a good match for your boat. When shopping for a deep cycle battery, you'll want to pay the most attention to the ampere-hour rating and reserve capacity. 

For starting batteries, focus primarily on the marine cranking amps. Consult all three rankings when searching for a dual-purpose battery.

Suppose you add electrical accessories to your boat. In that case, you may need to upgrade to a battery with a higher amp-hour rating, especially if you spend a lot of time trolling with the engine at a very low speed, beached, or at anchor while using accessories like the audio system.

Dispose of your old battery responsibly by taking it to a recycling center or returning it to a marine supply store.

Marine Batteries

Choosing the correct marine battery and maintaining it properly can make all the difference when you're out on the water. Knowing how to select, care for, and replace your battery will mean you enjoy smooth sailing all season long.

By following these tips, you'll maximize the lifespan of your marine battery and avoid unexpected issues so you can focus on what matters most – enjoying your time on the water.

Looking for more on basic boat maintenance? Read...

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