A Guide on Auxiliary Batteries

Lithium, AGM, gel, and more - which is best for your 4WD or caravan?

As a caravan or recreational vehicle owner, it’s important to understand the different battery types available for your vehicle. These battery types not only vary in their technology and composition but also in their capabilities and suitability for different purposes. 

Although many traditional battery types are being phased out, we’ll still explain how they work and how they compare to popular deep-cycle battery technologies like lithium and AGM. 

In this guide, we will explore the auxiliary battery types commonly used in caravans, motorhomes, and RVs to help you make an informed decision when it comes to powering your home on wheels. 

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What Specifications Should I Pay Attention To When Choosing an Auxiliary Battery?

When it comes to choosing the right auxiliary battery for your caravan, there are several key specifications you should consider. These specs will help you determine the battery’s performance and suitability for your needs. 

Consider the below factors:

  1. Depth of discharge: the depth of discharge indicates how much of the battery's capacity can be used before it needs to be recharged. A battery with a high depth of discharge will allow you to utilise more of its total capacity, providing you with more power for your application.
  2. Battery life: battery life refers to the lifespan of the battery, or how long it will last before needing to be replaced. It is important to choose a battery with a long battery life, as this will save you money and hassle in the long run.
  3. Charging time and efficiency: consider how quickly the battery can be charged and how efficiently it converts energy. A battery with a faster charging time and high charging efficiency will ensure that you can quickly recharge your battery bank and maximise use of your solar system.
  4. Size and weight: consider the physical dimensions and weight of the battery, as this will impact its portability and ease of installation in your caravan.

By considering these specifications and comparing different battery types, you can make an informed decision and choose the battery that best suits your caravan's power needs. 

What's a Deep Cycle Battery?

Deep cycle batteries are specifically designed to handle states of deep discharge, or depth of discharge (DoD), which refers to how much of the battery capacity is used in one full discharge.

Deep cycle batteries are built to provide a sustained power output over a longer period. They are commonly used in off-grid solar systems, including caravan batteries, as they can handle repeated charging and discharging cycles while maintaining high performance.

It’s important to note that all batteries reduce capacity with every discharge, some just more than others. Typically, the deeper you discharge your battery, the faster it degrades. Always pay attention to your battery’s indicated depth of discharge and avoid discharging it more than the recommended limit.

Deep cycle batteries are an excellent choice for caravan owners who want a reliable and efficient power source for their off-grid adventures. We recommend you consider two types of deep-cycle batteries for your recreational vehicle: lithium and AGM. While there are more options on the market, including gel and flooded batteries, these technologies are becoming less popular as battery technology and composition improve.

What's a Lead Acid Battery?

A lead-acid battery is a type of rechargeable battery that has been widely used for decades. It is a tried-and-tested option has proven to be reliable and durable, making it a popular choice for off-grid solar systems, including caravan batteries. 

There are many different types of lead acid batteries, including gel, AGM, calcium, and lead carbon.

Lead-acid batteries consist of lead plates submerged in a sulphuric acid electrolyte. During the charging process, the lead plates undergo a chemical reaction that converts electrical energy into stored chemical energy. This chemical energy is then released during the discharge process, providing power to your caravan.

Lead-acid batteries have less available capacity than lithium batteries. This just means that a lead-acid depth of discharge is shorter.

One of the main advantages of some lead-acid batteries is their cost-effectiveness. For example, AGM batteries are generally more affordable compared to other battery types, including lithium, making them an attractive option for those on a budget. 

Other lead-acid batteries such as gel, are on the pricier side but will last a lifetime due to their maintenance schedule. This is attractive for remote off-grid applications where longevity is critical.

Deep Cycle Battery Types

When it comes to powering your caravan or recreational vehicle, choosing the right battery is crucial. There are several types of auxiliary batteries available on the market, each with its own unique features and benefits.

​What is a Lithium (LiFePO4) Battery?

Lithium batteries are a type of rechargeable battery that has become ​increasingly popular in a variety of applications, including caravans and off-grid systems, due to their numerous advantages over other battery types.

LiFePO4 batteries are a safe and efficient battery type that, depending on usage patterns, will operate reliably with little maintenance for many years. 

A lithium battery consists of multiple cells:

  • 4x 3.2V cells in series for a 12V battery, and
  • 8x 3.2V cells in series for a 24V battery.

To achieve larger storage capacity in single batteries these cells may be arranged in a series parallel configuration. 

Most batteries these days also have a BMS (battery management system) internal to the battery. The job of the BMS is to manage the individual cells measuring voltage and temperature. In the event of the cells reporting outside of the set parameters the battery will disconnect power to the battery terminals. This is an important feature for the safety of the battery and in many ways makes LiFePO4 Batteries safer than lead acid batteries.

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What is an AGM Battery?

AGM batteries are the most recent category of lead-acid batteries released to the market. They don’t require regular maintenance or water refills like other lead-acid batteries, making them a popular hassle-free solution for caravan owners. 

The AGM battery design allows for the electrolyte liquid, or battery acid, to be absorbed into a woven fiberglass mat instead of being free-floating. This results in a spillage-proof and durable battery design. AGM is a good balance of price, reliability and lifespan.

What is a Flooded Battery?

Flooded batteries, also known as wet cell batteries, are a traditional type of lead-acid battery that were commonly used in caravans. These batteries have a liquid electrolyte that is free-floating within the battery.

Whilst flooded batteries require regular maintenance, including checking the electrolyte levels and adding distilled water as needed, they are known for their reliability and durability. They can handle high discharge rates and are suitable for off-grid systems. 

Flooded batteries are gradually being phased out as newer lead-acid technologies like AGM become more popular. This is because flooded batteries do require hands-on maintenance and are dangerous to install inside caravans due to the gassing they produce when charging.

What is a Gel Battery?

A gel battery is a sealed lead-acid battery that uses a gel electrolyte instead of a liquid. The gel electrolyte is made by mixing sulphuric acid with silica fume, creating a thick, gel-like substance that immobilises the electrolyte. This design prevents the electrolyte from leaking or spilling, making gel batteries a safe and maintenance-free option.

Gel batteries generally have a longer service life/cycle life than AGM batteries. We would use GEL over AGM in an off-grid installation where longevity is paramount. Gel is significantly more expensive than AGM batteries, however.

Are Lithium or AGM Batteries Better?

When it comes to choosing between lithium and AGM batteries for your caravan or vehicle auxiliary, both options have their own unique features and benefits. 

State of Charge

Lithium batteries typically have a higher state of charge compared to AGM batteries. This means they can store more energy and provide longer-lasting power for your caravan.

AGM batteries, on the other hand, may have a slightly lower state of charge compared to lithium batteries. However, they still offer a reliable and efficient power source for your off-grid adventures. 

Depth of Discharge

Lithium batteries generally have a higher depth of discharge compared to AGM batteries. This means you can use a larger portion of the lithium battery’s total capacity without affecting its performance or lifespan. 

AGM batteries, whilst still capable of delivering reliable power, may have a slightly lower depth of discharge. 

Consider your power requirements and how much capacity you will need to determine which is most suitable for your application.

Battery Life

Lithium batteries typically have a longer lifespan than AGM batteries. Lithium can continue to perform for up to 10 years or more, depending on usage and maintenance. 

AGM batteries, on the other hand, have a slightly shorter lifespan but can still provide reliable power for several years.

Charging Time and Efficiency

Lithium batteries generally have a faster charging time than AGM batteries. This means they can be recharged more quickly, allowing you to quickly replenish your battery bank and get back to enjoying your free camping. In addition, lithium batteries have high charging efficiency, meaning they can convert energy more efficiently. This allows you to make the most of your solar system and maximise the use of your battery’s stored energy. 

AGM batteries, whilst still offering reliable power, may have slightly longer charging times and slightly lower charging efficiency.

Size and Weight

Lithium batteries are known for their lightweight design, making them ideal for applications where space is limited, such as in caravans or canopies. These batteries are compact and easy to handle, allowing for easy installation and portability. 

On the other hand, AGM batteries are generally heavier and bulkier compared to lithium batteries. However, they still offer a manageable size and weight, ensuring they can fit comfortably in your caravan or motorhome.

Ultimately, the choice between lithium and AGM batteries will depend on your specific needs and preferences. Consider factors such as power requirements, budget, and the size and weight of the battery. By understanding the pros and cons of lithium and AGM batteries, you can make an informed decision and choose the battery that best suits your vehicle's power needs.

Auxiliary Batteries and Off-Grid Solar Systems

Choosing the right battery for your off-grid solar system is a crucial decision that will impact the performance and longevity of your system. With various battery types available, it can be an overwhelming choice to make. However, by considering a few key factors, you can make an educated decision on the right battery for your needs.

Power Requirements

Consider your power requirements. Determine the amount of energy you will need to power your caravan and the appliances you plan to run. This will help you determine the capacity of the battery you need.

If you have higher power demands, you may need a larger battery bank or a battery type with a higher energy capacity, such as a deep cycle lithium or AGM battery.

Charging Capabilities

Of course, you should be looking to wholly charge your supplement your battery charging with solar panels. This means you need to consider the charging capabilities of your solar panels. Different batteries have different charging requirements, so it's important to ensure that your solar panels are capable of charging your chosen battery.

For example, lithium batteries have a faster charging time compared to other battery types, making them ideal for systems with limited charging hours.

Lifespan and Durability

Some battery types have a longer lifespan than others. This means that you will need to replace the battery less frequently, saving you time and money in the long run. A lithium battery will generally continue to perform at a high level for 10 years or more and will require very little maintenance during its lifespan. A gel or flooded battery in comparison could last decades, but will require regular hands-on maintenance. 

Durability is also important to consider, especially if you plan on using your system in harsh or exposed applications. 


Batteries vary in price, with some being more affordable than others. It's important to choose a battery that not only meets your power requirements but also fits within your budget. 

Lithium and gel batteries are durable choices that will last a long time, but they come with a pricier tag. 

AGM batteries in comparison, may have a slightly shorter lifespan but they are more affordable. 

To Wrap Up

By considering all the above and doing your own research, you can choose the right auxiliary battery for your off-grid system and recreational vehicle. You can always consult with a professional or trusted supplier (like us!) to ensure you’re selecting the right gear for your unique needs.

What We Recommend


Invicta Xero 12V 200Ah LiFePO4 Battery (Bluetooth)
  • IEC62619 Certification
  • Built-in Bluetooth Monitoring
  • Multiple Communication Ports


DELTEC ELiVATE 140Ah Lithium Battery (Bluetooth)
  • Built-in Bluetooth Monitoring
  • Internal BMS
  • Excellent quality for the price


Enerdrive B-TEC 12V 100Ah LiFePO4 Slim Battery
  • Built-in Bluetooth Monitoring
  • Suitable for narrow spaces
  • Internal BMS



Fullriver DC 12V 150Ah AGM Battery
  • Valve Regulated Lead Acid (VRLA) Technology
  • Deep Cycle Battery
  • Low-Self Discharge Rate


DELTEC 12V 120Ah Deep Cycle AGM Battery
  • Valve Regulated Lead Acid (VRLA) Technology
  • Deep Discharge Recovery
  • Consistent Power Delivery


Ritar 12V 120Ah Deep Cycle AGM Battery
  • Valve Regulated Lead Acid (VRLA) Technology
  • Deep Cycle Battery
  • High Power Density


Springers Solar | Your Trusted 12V/24V Components & Accessories Supplier

We only stock the best brands in the extra-low voltage industry for the best prices - you can trust that when you buy gear from Springers, you are setting up your system to perform long-term. We don't waste our time or your time with low-quality products. 

With an in-house team of 12V/24V experts, we can offer advice and support as you set up your off-grid, off-road, or DIY battery system. We are Queensland-based and house our stock, so check out our online store here or visit us at Lawnton or Capalaba for in-store help. 


Up to 70% off all mobile solar, off-grid, and auto energy system components and accessories.


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