What Is A Deep Cycle Battery?

What Is A Deep Cycle Battery?

When you hear of the term battery, what comes to your mind? Just a little gadget that helps you store energy and provide it whenever it is needed in electrical form. Well, that is true but it is not that simple.

Batteries, even in the simplest form, are designed for a specific purpose. These specific purposes are what makes them so different from each other. Batteries can be classified into hundreds of types based on their specific functions, their constructions, and many other reasons. So in order to choose the most suitable battery for you, it is essential to thoroughly understand different types of batteries. 

In this article, we are going to dive into the topic of batteries and throw some light on different types of batteries, mainly a deep cycle battery.

What really is a deep cycle battery?

The deep cycle battery is made up of lead and it is usually designed for providing sustained power for a longer span of time and for running without any disturbance until it is discharged by 80% or more. This discharging level refers to the term "deep cycle" in it. As opposed to common batteries, which release only small bursts of energy, the deep cycle battery follows a particular pattern in order to give off the energy.

It is also essential to notice that even though the deep cycle battery is capable to be discharged over 80%, it is not recommended to always do that. A safer and more reliable percentage for a battery as an ultimate discharging limit is 45%.

A thorough analysis of starter battery in comparison with the deep cycle battery

Starter Battery:


As the name indicates, the starter battery is the one responsible to start up the machinery. They are usually called "the sprinters of the battery‘s world". The main purpose of designing them is to give an instant spark of energy usually for the functions of starting up motors or anything else. They are instant energy providers.


Its functioning can be understood by the examples of a car battery. We start up the car and the battery provides instant heat in order to ignite the petrol and then the job is done. Hence, the instant spark will be enough and there will be no need for a battery to keep discharging and recharging. This is where a starter battery is required.


As understood by the above example, it is used only where an immediate spark of energy is required. However, in applications where continuous energy is required, it cannot fulfill the requirements. As the design is based on the necessity of an instant spark, it usually does not have the ability to engage in the charging-discharging and recharging cycles. In fact, extreme discharging can cause the battery‘s functionality, lifespan, or performance or thoroughly deform it.

 Deep Cycle Batteries

To solve this problem, the deep cycle batteries -- the marathon runner of the world of batteries--were introduced. These batteries do not offer an immediate spark of a lot of energy, instead, they are designed to provide a lesser amount of energy in a single run. The remaining capacity of the battery is stored to be used later in time. Hence, they last for a longer time.

After seeing the comparison of these batteries, the question arises that is it possible to combine these two in order to build something that is beneficial in both cases? Something through which we can get all the benefits provided by both the batteries. The battery designed for this purpose is called a dual-purpose battery.


The purpose of these batteries is to provide the combined benefits from both the starter battery and the deep cycle battery. Hence, they provide the function of both starting and cycling. These functions make them the ideal choice when you are working with a small footprint. In order to start up the machine, they provide an instant very high boost of energy and for the rest of the time, i.e., when continuity is needed, they provide the continuous amount of low amperage.

Discharging ability of the deep cycle batteries

When we talk about the starter batteries, as described in the above text, high levels of discharging can be very harmful to the regular functions of the battery. But the deep cycle batteries are designed on a different pattern. They are designed to perform long-running functions. This is why a good amount of durability for discharging and recharging cycle is required in them. They have the capability to discharge a greater amount of their stored energy.

However, the individual discharging capability and the safety limit of the batteries vary from one battery to another. Some batteries are only capable of discharging up to the limit of 45% of their total energy reserves. However, some strong batteries can even go up to 100% of their total energy reserves. However, it is advised to always look for the recommendations by the manufacturers themselves in order to know about the discharging capability of it.

Applications of the deep cycle battery

We have studied that the starter batteries give off an immediate spark of a huge amount of energy. That is required in applications where the initial burst of energy is required such as a car battery. However, where we can use the deep cycle batteries? Their applications are diverse. The main usage is in the machines where continuous power is required for a comparatively longer span of time.

Some common examples include:

  1. Marine applications
  2. Golf carts
  3. Electric floor cleaning machines
  4. Electric scissor lifts
  5. Off-grid renewable energy
  6. Recreational vehicles
  7. Electric wheelchairs
  8. Materials handling, including forklifts
  9. Electric scooters
  10. Trolling motors on boats
  11. Navigational devices on a boat ( In case the primary motor stops working properly)
  12. Renewable Energy system


Classification of Deep Cycle Batteries into different types

Like any other battery, deep cycle batteries also have classification into different types. The main working and the operating procedure are the same for all the types. However, their building materials, building procedure, and other factors provide the base for the classification of deep cycle batteries into further different types. These types may have their own advantages or disadvantages that are going to be discussed. Have a read to the text written below.

Flooded Lead-Acid deep cycle battery

A flooded lead-acid battery, better known as a wet cell, is one of the oldest deep cycle batteries to ever be made. It is also called a wet cycle battery because of the reason that it contains a liquid electrolyte in it that is made up of sulfuric acid added with water. It can be explained with the example of a car. We need to open a tab at the top of the battery and then add water to it whenever it is required. This is because it has a flooded lead-acid battery which requires adding water after uniform intervals in order to maintain its working. 

However, due to the presence of liquid inside them, these batteries require some extra maintenance. Proper ventilation is required and also these batteries should always stay upright all the time. Hydrogen is continuously produced in the process and hence there should be a proper way to let the hydrogen gas out. Otherwise, it is also a highly observed phenomenon in deep cycle batteries that they spit the vents in the charging process. This causes any acid residue that stays not only on the cover of the battery but also on the battery tray.

Another maintenance is also essential for this type of deep cycle battery may include cleaning the residual acid from the cover of the battery, adding water, and others. One other common disadvantage of this type is that it has a considerable weight and it is hard to carry it. Also, if we consider the ratio of weight and provide energy, it is also not very advantageous over other types. This is the reason why this type of deep cycle battery lost its usability and popularity.

Valve Regulated Lead-Acid (VRLA) 

Also called a Gel and AGM battery, this is another type of lead-acid batteries but it can be called an improved version. As we have studied the presence of liquid in the lead-acid battery makes it hard to maintain the battery, this, on the other hand, does not contain flowing liquid electrolytes in them. With this improvement, no water is required to be added from time to time and hence it becomes easy to maintain. 

However, it is way more costly when compared to the liquid electrolyte ones. Another disadvantage is that they will not last for longer life spans in a lot of the recent applications.

Gel batteries use an electrolyte in gel form meanwhile AGM batteries use the electrolyte that is absorbed in a glass matt. If they are properly maintained according to instructions and charged, discharged, and recharged well, they won‘t release any gases. However, if the maintenance conditions are risked, the safety valve will open and will release the gases. Comparing to the liquid electrolyte ones, they don‘t require the condition of upright and they also have lower risks of spillage, corrosion, or any other common problem that occur because of the flow of the fluid.

These few reasons make it popular in many applications including recreational vehicles, boats, and many more.

Lithium-Ion battery 

Lithium-ion batteries are undoubtedly the future of the world of batteries. Especially, they define the new eras of the deep cycle batteries. They introduce a person to an infinite amount of advantages. The maintenance required is almost zero compared to others. It can endure extreme charging and discharging cycle. In other words, it discharges deeply without getting damaged. Moreover, the recharging procedure is much faster than in other types.

Knowing about above all advantages, one must think that they cost very high and are typically more expensive than other types. However, it is not true. They cost almost the same as lead-acid batteries or might even cost less. This is the reason behind their popularity.

The advantage list does not just end here. They carry a lot of other benefits over lead-acid batteries too. They are light in weight hence highly portable. The rate of discharge doesn‘t really affect their performance or capacity. Even if you use them in the middle of the recharging process, they will not get damaged and will provide similar benefits. Moreover, they provide the power in all of their discharge cycle.

Comparison Factors of Lithium-Ion and Lead-acid Batteries


Capacity is a highly varying factor. It differs in both the lead-acid battery and Lithium battery. Usually, the capacity is stated in relation to their rate of discharge. Lithium-ion batteries are capable of providing up to 100% of their total capacity. Their rate of discharge does not really affect their capacity. In contrast, lead-acid batteries usually lose their power or capability when discharging exceeds a defined limit.


Both the lead-acid battery and the lithium-ion battery are temperature sensitive. Their performance can decrease in colder weather. However, the changes found in lithium-ion batteries are significantly less than the lead-acid batteries. For example, at 0°C, a lead-acid battery can face a reduction in the capacity of over 50% meanwhile for lithium-ion battery, it is no more than 10%. 


The lifespan of deep both types can be evaluated by different factors. However, the lithium-ion battery shows much more tolerance and shows less dependence on these factors. The lead-acid battery is more vulnerable to any changes. Some of these factors are 

  1. Level of maintenance
  2. Proper discharging and recharging cycle
  3. Watering

In the case of lithium-ion batteries, watering is not required. Also, the recharging and discharging does not have a lot of impact on its performance. They do not require very high maintenance either. So they do not show that much vulnerability. However, some other factors can impact their life span. These factors include severe discharging, physical abuse, or extreme environmental conditions like temperature, heat, and pressure.

 So this was the comparison of all the deep cycle batteries. We hope that it made your battery choices even clearer!