The demand for high-capacity batteries has increased in recent years for many applications. To meet this high demand, many types of batteries are now available.
The top contenders suitable for most applications are lithium and AGM batteries. Many people ask us: which should I choose – an AGM or lithium battery?
This article gives a detailed overview of lithium-ion and AGM batteries and how they fare against each other on various parameters. It also explains which one is the better choice for any particular situation.
How Does the Technology of AGM and Lithium-ion Batteries Differ?
While the function of both batteries is to provide an electric current, their underlying technologies are entirely different.
AGM stands for Absorbent Glass Mat. This technology is based on the principle of lead-acid batteries. Many types of lead-acid batteries are available, and Absorbent Glass Mat is the newest.
An Absorbent Glass Mat battery contains two plates: a positive plate and a negative plate. These plates consist of an acid-absorbed glass mat. Typically, lead-acid batteries contain free-flowing acid, but that is not the case in Absorbent Glass Mat technology.
Lithium batteries are one of the best options available. They have replaced most of the other alternatives. Lithium batteries are most prominent in deep cycling applications.
There are many types of lithium options available on the market. However, the working principle of different lithium batteries is the same.
During charging, lithium ions travel from the positive to the negative electrodes through an electrolyte. Once charged and the charger is removed, the ions travel back from the negative electrode to the positive electrode, creating the current.
LiFePO4 (LFP) is the latest evolution of lithium batteries that works on the same principle but provides countless added benefits.
How Do Lithium Batteries and AGM Batteries Compare?
To understand the difference in performance between the two, let’s evaluate them on the different parameters that matter. We will also decide which battery is better for each parameter so you can make an informed decision.
Depth of Discharge (DoD)
When you start discharging a battery beyond a specific limit, it begins to suffer damage. Depth of discharge measures the percentage of the initial charge that can safely be discharged without causing harm.
Modern lithium-ion batteries have a depth of discharge of 98%. So you can discharge almost the entire charge without damaging the unit. This provides optimal conditions for use with most of the stored power available.
Like other lead-acid batteries, the depth of discharge is about 80% when new and 50% when older. This makes them less competitive compared to lithium-ion batteries.
Winner: Lithium-ion batteries have the highest depth of discharge and a longer operating time.
Regardless of type, a gradual decrease in performance occurs over a battery’s lifespan. There is a point in time when the battery will become useless.
LFP technology is known for its superior durability, typically degrading by less than 1% per year and providing about a 10,000 charge cycle life.
These degrade quickly, providing a useful lifespan of about 500 charge/discharge cycles.
Winner: A lithium-ion battery has a considerably longer lifespan, typically about six times longer than an AGM battery.
Size and Weight
Size is a key concern for people working with limited space, such as owners of caravans.
Lithium-ion batteries weigh less due to the absence of any liquid acid. Additionally, since they have a higher depth of discharge, a smaller lithium-ion battery can provide the same power as a larger lead acid battery.
AGM batteries contain absorbed liquid acid that creates added weight. Additionally, a low depth of discharge means that you need a high-capacity (big) battery for any given application.
Winner: Lithium batteries are the better choice in terms of weight and size.
Embodied Energy (Energy Density)
Embodied energy refers to the energy required to manufacture a battery. This is closely related to energy density, which refers to the amount of energy stored relative to the battery’s size.
Lithium-ion batteries are smaller than AGM batteries for any particular application. Therefore, they have lower embodied energy and a higher energy density than their AGM counterparts.
Winner: Lithium-ion batteries are 500% better than AGM batteries when we consider the energy required to manufacture them in ratio to the energy storage provided during their lifespan.
Charge Time and Efficiency
Generally, more efficient batteries tend to have a shorter charging time because of fewer electrical losses. A shorter charge cycle leads to better utilisation of the current used to charge it.
Due to their higher efficiency, smaller lithium batteries can do the same job as larger AGM batteries. They also charge faster.
Although they charge considerably faster than wet lead-acid batteries, AGM batteries still charge much slower when we compare them with lithium-ion batteries.
Winner: Lithium-ion batteries charge faster than AGM batteries and over four times faster than general lead-acid batteries.
Cost is one of the most important factors when deciding between two battery types. There are two cost factors to consider – the initial cost and the cost per kWh. Here we will discuss the initial cost of each option.
Lithium-ion batteries require a higher upfront cost. Although lithium-ion batteries outperform AGM batteries when considering all other parameters, the initial cost is much higher.
Winner: AGM batteries win when you compare the initial cost. However, if considering the lifetime cost, lithium-ion batteries are the better choice since they can be used for a considerably longer time.
Learning about the maintenance requirements of a battery is crucial before buying one. Also, maintenance often leads to added costs and modifications you need to make to your battery setup.
Lead-acid batteries are notorious for high maintenance requirements, such as regular electrolyte top-ups. Although AGM is a type of lead-acid battery, it does not require such maintenance steps. This is because it is a completely sealed design.
However, even so, AGM batteries require appropriate venting for the evacuation of gases. Additionally, you need to monitor the charging process, as overcharging can cause permanent damage.
Lithium-ion batteries are a fit-and-forget solution which decreases the maintenance requirements. This is especially true for LFP models.
For instance, the LiFePO4 models provided by Eco Tree Lithium come with an inbuilt battery management system (BMS). This system cuts off charging when the battery is fully charged to protect it from overcharging. Learn more about overcharging lifepo4 batteries.
Winner: Lithium-ion batteries offer a completely maintenance-free experience.
In recent decades, more and more effort has gone into making processes and equipment less damaging to the environment. This also applies to batteries, and users prefer technologies incorporating the go green initiative.
Lithium-ion batteries are a completely sealed system and do not release any chemicals. Additionally, LFP technology avoids using toxic chemicals such as Cobalt. Instead, it uses more stable elements such as Phosphate.
This is why LFP technology is considered the most environmentally friendly battery option available.
While AGM batteries are a greener option than conventional lead acid batteries, they still emit harmful toxic fumes to the environment. Additionally, their constituents are also very damaging.
Winner: Lithium-ion batteries are more environment-friendly than any lead acid battery, including AGM.
Since buying a battery is a significant investment, users want to ensure a warranty is in place covering their investment. Extended warranties indicate the manufacturer’s endorsement of a longer lifespan for their products.
Lithium batteries usually come with warranties of three years or more. In fact, Eco Tree Lithium’s LFP batteries come with a written warranty of 6 years.
Since an AGM battery has a shorter life than LiFePO4 versions, you obviously get a short warranty with an AGM battery. Generally, you can expect an AGM battery to be covered for about 1-2 years.
Winner: Lithium iron phosphate batteries offer the best warranties, especially if you buy them from a reliable source such as Eco Tree Lithium.
Not paying proper attention to battery safety can cause serious injury to health and property. This is especially true when you consider that most deep-cycle applications involve close proximity to human activities.
Lithium-ion batteries produce no build-up of gases, and there are no toxic liquids. You can use them without any additional safety precautions required. Also, Eco Tree Lithium batteries come with added security measures such as a fire-resistant case.
Although a sealed battery, like gel batteries, AGM technology still produces a considerable build-up of gases such as Hydrogen. Without proper ventilation, these gases can ignite and cause battery explosions. Additionally, these are also very poisonous gases.
Winner: If safety is your concern and you want an easier-to-handle battery, lithium-ion should be your go-to choice.
Application Comparison of AGM vs Lithium Battery
Now that you know how AGM and lithium batteries perform on different parameters, let’s evaluate how well they handle specific applications.
Batteries are not always a one-size-fits-all product. For some applications, specific models can perform better than others.
Let’s see the particular applications for which AGM and lithium batteries are the perfect fit:
If you are considering choosing a leisure battery for motorhomes or caravans, LFP batteries are the perfect fit. In the RV battery market, people want a product that offers deep cycle life with high safety and low maintenance.
Lithium leisure batteries, especially lithium iron phosphate batteries, are the ones that win on all these parameters. When using lithium batteries in a motorhome, it is a good idea to use dedicated battery chargers instead of the built-in charger.
Any liquid or gel batteries are not considered a good choice as a marine battery because the surface level continually changes with the vessel’s movement.
However, since most lithium batteries contain no liquids, they work very well for marine applications.
Freezing conditions are challenging for battery operation because battery charging can be problematic at such temperatures. This is one particular scenario where AGM batteries perform better than lithium batteries.
However, high-quality lithium batteries such as Eco Tree Lithium’s LFP batteries come with a self-heating function. This function allows them to work just as well as AGM batteries, even in sub-zero conditions.
Solar Energy Storage
Due to their high energy density, depth of discharge, and long warranty, lithium iron phosphate batteries are the best option for solar storage. The only thing that might make people consider an AGM counterpart is the low initial cost of a single battery.
However, considering the lifetime cost, a single lithium battery can perform equivalent to 16 AGM batteries. Therefore, for solar storage applications, LFP batteries are the best choice.
Similar to the RV battery market, the UPS market favours LFP batteries. They are safer and completely maintenance-free, making it easier for people to own one in the long run. Not to forget, they provide a higher capacity than a comparable AGM battery.
Electric Vehicle Battery
Owners of electric vehicles want to travel a longer distance on a single charge. This is why manufacturers prefer LFP technology in electric vehicles. LFP power units often come with a six-year warranty as well.
Which Battery to Choose?
As is quite evident, Lithium-ion batteries are considerably better than AGM gel flooded batteries in every key aspect. While the initial cost of buying a battery can be high in the case of lithium batteries, they make up for it by their considerably longer lifespan and greater capacity.
Once you quickly review the information for AGM and lithium-ion batteries, you will realise that we aren’t even looking at a fair competition. Lithium-ion batteries are better than AGM ones by an impressive margin.
Many people still look for a comparison when they see the attractive lower cost of AGM. What is forgotten is that this cost also brings reduced capacity, inferior safety, and a fraction of the lifespan. You will need more batteries than a single lithium model to deliver the same power.
Therefore, when you plan to buy a new battery, it is best to choose lithium-ion. For optimal performance, we recommend Eco Tree Lithium’s LFP batteries which outperforms any other battery.
Frequently Asked Questions
Here are the answers to some commonly asked questions regarding AGM flooded lead acid batteries and lithium-ion battery banks.
1. Is AGM better than a lithium battery?
No, lithium batteries offer a far superior performance than an AGM battery. You would need an AGM battery bank to achieve the same amount of performance as a single lithium battery.
2. What is the main disadvantage of an AGM battery?
The main disadvantages are a shorter lifespan, less capacity, and longer charging times.
3. Can I swap my AGM battery for a lithium battery?
Yes. You can easily swap your AGM battery bank for a lithium battery. Even a lower-capacity lithium battery system can offer the same power as two AGM batteries.