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Ultimate Guide - Differences on Marine Deep Cycle and Starting Battery

10 May 2023
Ultimate Guide - Differences on Marine Deep Cycle and Starting Battery

As a boating enthusiast, you know that a reliable battery system is key to a smooth and enjoyable journey on the water. Choosing the right marine battery for your boat is thus not only important but also essential. Two types of marine batteries that are commonly used are the marine deep cycle battery and the marine starting battery. In this article, we will discuss both the types in detail.

Part 1: Understanding Marine Deep Cycle Battery

Marine deep cycle batteries are designed to provide continuous power for long periods of time at a lower voltage. These batteries are called "deep cycle" because they are built to discharge up to 80% of their capacity without causing damage to the battery. Deep cycle batteries are often used to power trolling motors, fish finders, and other devices that require continuous power over long periods.

starter vs deep cycle battery

1.1 Deep Cycle Marine Battery Design Features 

Deep cycle marine batteries are designed to provide reliable power for an extended period of time. These batteries are built differently than starting batteries because they are designed to deliver long-lasting power at a lower voltage. Below are some of the key design features of deep cycle marine batteries:

1.Thicker Plates

Deep cycle batteries are designed with thicker plates compared to starting batteries. The thicker plates offer a greater surface area for active material and more room for the electrolyte, thus allowing the battery to deliver more sustained power over a longer period.

2.More Active Material

The active material in the plates of deep cycle batteries is denser than that in starting batteries. This means that there is more active material per unit area, which allows the battery to have a longer lifespan with more cycles of discharge and recharge.

3.Low Discharge Rates

Deep cycle marine batteries are designed to deliver low discharge rates, enabling them to provide continuous power for long periods of time. This feature is crucial for powering accessories like trolling motors, fish finders, and other electronics that require constant power over an extended duration.

4.Thicker Separator

Deep cycle batteries have a thicker separator which is designed to prevent short circuits between the positive and negative plates. This separator helps to minimize the risk of internal damage to the battery due to physical shocks or vibration typically experienced on board boats.

5. Heavy Duty Construction

Deep cycle marine batteries are designed to handle rough marine conditions. The construction features include enhanced resistance to vibration, shock, and corrosion. Marine batteries are also designed to be spill-proof to avoid damage to the boat or the environment in case of leaks.

marine deep cycle battery

6. Multiple Charging Options

Most deep cycle marine batteries can be charged through multiple options like on-board chargers, solar panels, or even wind turbines. They can handle trickle charging and bulk charging too, depending on the charging source available. Read on 3 reliable ways to charge LiFePO4 lithium marine deep cycle batteries

1.2 Type of Marine Deep Cycle Battery

1. Lead-acid Battery

Lead-acid batteries are the most commonly used deep cycle batteries and are available in two types - flooded lead-acid (FLA) and sealed lead-acid (SLA). FLA batteries require regular maintenance as the electrolyte level needs to be checked and topped up periodically. On the other hand, SLA batteries are maintenance-free.

lead acid battery

However, there are several drawbacks associated with this type of battery.

Firstly, they have the lowest C-rating among the battery types discussed today, which means that they cannot be charged or discharged quickly without causing damage.

Additionally, they require a more advanced charger that can provide Equalization charges to ensure they last as long as possible, and failure to maintain them properly can lead to sulfation. They also cannot be left in a partial state of charge or discharged below 50% of their rated capacity, meaning that their usable power is significantly less than their rating.

Moreover, these batteries are position-sensitive, and submerging them can release dangerous chlorine gas. They require constant float charging, even when not in use, and periodic refilling with water is necessary.

Lastly, good ventilation in the battery compartment is crucial to prevent potential explosions caused by the release of hydrogen gas during charging.

2. Lithium-ion Battery

Lithium-ion (Li-ion) batteries are gaining popularity in the deep cycle battery market due to its various advantages over the traditional lead-acid battery. Li-ion batteries typically have higher energy densities, longer lives, and are lighter in weight compared to lead-acid batteries; making them ideal for marine applications. The only type of lithium ion battery approved for marine use is currently the lithium iron phosphate (LiFePO4) battery.

marine deep cycle battery

At Litime, we offer a wide range of LiFePO4 batteries that are designed to meet the specific requirements of marine vessels. Our Lithium marine batteries are lightweight and compact, making them easy to install, remove, and transport as needed. They are also less prone to sulfation and are capable of fast charging, ensuring that your boat is always powered when needed. So, if you are looking for a reliable and high-performance marine battery, look no further than Litime's range of Lithium-ion batteries. Check What Size Battery for Trolling Motor to find the one suits.

Part 2 Understanding Marine Starting Battery

Marine starting batteries also called cranking batteries are designed to provide a burst of power for a short period of time at a higher voltage. These batteries are used to start the engine of the boat, and once the engine is running, the alternator takes over to provide power to the boat's electrical system.

2.1 Marine Starting Battery Design Features

1. Thinner Plates

The thinner plates in marine starting batteries allow for a larger surface area and more active materials, which provides a burst of high cranking power needed for starting the engine. The thinner plates are also designed to withstand the high current draw during engine starting and to recharge quickly. However, the thinner plates are not suitable for repetitive deep discharging like a deep cycle battery. Therefore, it is important to use the correct type of battery for specific applications to ensure optimal performance and longevity.

2. Corrosion Resistance

Marine starting batteries are often exposed to saltwater and other corrosive elements. To prevent corrosion and maintain battery health, they are designed with materials and coatings that resist rust and moisture.

3. Vibration Resistance

The movement of the boat and the power of the engine can cause significant vibration that can damage the batteries. Therefore, marine starting batteries are built to withstand vibration and shock.

4. Maintenance-free

To prevent the need for frequent maintenance and ensure longevity, marine starting batteries are often maintenance-free. They require no addition of electrolyte or water, which helps in reducing maintenance efforts and time.

5. High cranking power

Marine engines require rapid and high power cranking for starting. Hence, marine starting batteries are designed to deliver high cranking power, which makes it easier for the engine to turn over.

6. Multi-positioning

Marine starting batteries are designed with multi-positional mounting to allow easy installation in tight spaces. This feature ensures that the battery is secure while being mounted in different orientations, including upside down.

2.2 Types of Marine Starting Battery

There are two main types of marine starting batteries:

1. Flooded batteries:

Flooded batteries, also known as wet-cell batteries, are the most common type of marine starting battery. They use lead-acid chemistry and require maintenance, which includes adding distilled water to the cells periodically to replenish the water lost during the charging process. Flooded batteries are typically cheaper than other types of marine batteries.

2. Absorbed glass mat (AGM) batteries

AGM batteries are maintenance-free and have a longer service life than flooded batteries. They are designed with a glass mat that absorbs and holds the battery's acid electrolyte, so there is no need to add water or maintain the electrolyte level. AGM batteries are also vibration-resistant and can discharge at a higher rate than flooded batteries, making them a good choice for high-performance boats. However, AGM batteries are more expensive than flooded batteries.

Part 3 What is Dual Purpose Marine Batteries

Dual purpose marine batteries are a type of battery that is designed to serve two functions - starting an engine and powering electrical components on a boat. They are typically a hybrid of a starting battery and a deep-cycle battery, combining the high cranking power of a starting battery and the deep cycling capabilities of a deep cycle battery. Dual purpose marine batteries are used by boat owners who want a single battery to handle both starting the engine and powering electrical systems. This eliminates the need to have separate batteries for each purpose, which can save space and reduce complexity.

While they are not the best option for either starting or deep cycling, dual-purpose marine batteries offer a good compromise between the two.

Generally, dual-purpose marine batteries are most suitable for smaller boats, such as fishing boats, ski boats, and small pleasure crafts that do not have high electrical demands and do not require a high cranking power to start the engine. This includes boats that have basic electrical systems, such as lights, fish finders, and radios.

However, if the boat has a larger electrical system, such as a refrigerator, air conditioning, or other high-demand electrical components, a dual-purpose marine battery may not be sufficient. In such cases, a dedicated deep cycle battery is preferred. Additionally, if your boat has a high horsepower engine that requires a lot of cranking power, then a dedicated starting battery would be the best choice.

Therefore, it is essential to carefully evaluate your boat's need before selecting a marine battery. If you have any concerns or need help selecting the right battery for your boat, please visit our website or consult a professional marine electrician.

Part 4 Maintenance of Marine Batteries

Both marine starting and deep cycle batteries require regular maintenance to ensure their longevity and optimum performance. Following are some tips on maintaining your marine batteries:

  1. Clean the battery terminals regularly to avoid corrosion.
  2. Check the fluid levels regularly in flooded batteries and top them up with distilled water if necessary.
  3. Charge your batteries with onboard chargers or smart chargers designed for marine use.
  4. Store your batteries in cool and dry places during the offseason.

If using LiFePO4 batteries, it would be less likely to get terminal corrosion, learn how to maintain LiFePO4 battery.

FAQS about Deep Cycle and Cranking Battery

1.Can lithium batteries be used for marine starting battery?

In most cases, YES but not for engine starting applications. It is still a common choice for lithium starter batteries.

2. Can I use the same battery for starting and trolling?

Boaters may be tempted to reduce the number of accessories and additions to their vessel. However, choosing this approach can lead to higher costs and time consumption in the long run. It's challenging to combine the performance of a cranking battery, which is designed to provide a large burst of power to start an engine, and a deep cycle battery, which is engineered to provide sustained power over a long period of time, into one battery as they serve different purposes.

Using the same battery for starting and trolling can be detrimental as it can risk draining the battery too low during trolling, leading to reduced overall lifespan, or permanent damage. Moreover, without proper charging between uses, the battery may not have enough power left to start the engine at the end of the day.

The best approach is to use a dedicated starting battery for engine starting and a separate deep cycle battery for trolling and other electrical needs. Some boats even use a dedicated battery bank for each purpose. This ensures that each battery performs optimally and serves its specific purpose, thus maximizing their lifespan.


We have introduced the 2 types of batteries in detail, if you are looking for the deep cycle battery for your marine, lithium Iron Phosphate (LiFePO4) batteries are an excellent choice due to their efficiency, long lifespan, and ability to withstand deep cycle usage.

At Litime, we specialize in high-quality LiFePO4 marine batteries designed specifically for the rigors of marine use. Our batteries are lightweight, maintenance-free, and offer excellent performance, making them the perfect solution for powering your boat's electrical systems. Contact us today to learn more about our high-quality marine batteries and how we can help meet your marine power needs.

marine deep cycle battery

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