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The Ultimate Guide to AGM Batteries

Jan. 31, 2024
Author: 佛山市科特电池有限公司 From: 佛山市科特电池有限公司 Modify: Jan,31,2024

AGM batteries, short for Absorbent Glass Mat batteries, have become indispensable in various applications due to their advanced technology and numerous benefits. AGM batteries utilize Absorbent Glass Mat technology, where the electrolyte is absorbed into a glass mat separator, providing several advantages over traditional batteries. 

But what does absorbent glass mat (AGM) actually mean? How does it improve the battery's performance relative to standard lead-acid batteries?

Let’s review some basics of SLA (Sealed Lead Acid) battery construction. All SLA batteries consist of lead plates (positive and negative) and an electrolyte, which are then arranged into "cells" and placed into a battery case. Some of these batteries also have valve regulation that allows the small amounts of gas that occurs during the recombination process to escape during charging. Although these batteries allow gas to escape, they are spill-proof batteries (sometimes called valve-regulated lead acid, or VRLA) and can be safely operated in almost any position (the only limitation is that they are not recommended for use upside down). Because they are sealed, there is no need to add electrolyte after the manufacturing process, and any gas produced enters the recombination cycle.

​Construction of Agm Battery

AGM (Absorbent Glass Mat) batteries follow the basic principles of standard Sealed Lead Acid (SLA) batteries. The key difference lies in the addition of glass fiber mats between each negative and positive plate to absorb the electrolyte. These mats, functioning like sponges saturated with electrolyte, prevent the battery from leaking.

In the AGM battery structure, the electrolyte is immobilized in the appropriate position. The glass fiber mats act as a medium, allowing the electrolyte to move through them. This design maximizes the surface area for the electrolyte to contact the plates without excessive liquid submersion, akin to creating a large surface area without flooding the battery. AGM batteries contain just enough electrolyte to keep the mats moist, and in the event of battery rupture, there is no free liquid leakage. This minimizes the amount of electrolyte in the battery while still providing energy similar to traditional SLA batteries.

Types Of Agm Batteries

Not all AGM batteries are created equal. Deep cycle, starting, and dual-purpose AGM batteries cater to different needs. While AGM batteries are a popular choice for deep cycle, they are also a popular choice for starting batteries since AGM batteries have a depth of discharge (DoD) of 80% compared to a standard flooded battery's 50% DoD. This is because it has low internal resistance and can deliver large current loads quickly. AGM batteries are also used as start-stop batteries in modern cars because flooded batteries are not strong enough to handle the repeated cycles in start-stop applications, which can cause the battery to fail after only a few years of use.

Each cell in an AGM battery has a voltage of 2 volts, so AGM batteries are available in a variety of voltages, including the popular 12V models.

The Ultimate Guide to AGM Batteries

Kete AGM Battery


Charging An Agm Battery

Charging AGM batteries involves a process that takes advantage of the unique characteristics of Absorbent Glass Mat (AGM) technology. One notable advantage of AGM batteries is their rapid charging capability, which is approximately five times faster than that of standard flooded lead-acid batteries. This accelerated charging speed is a key feature that makes AGM batteries a preferred choice in various applications.

AGM batteries are designed with a specialized construction that includes a glass mat separator to absorb and hold the electrolyte. This design not only enhances the overall performance of the battery but also allows for faster and more efficient charging. The Absorbent Glass Mat acts as a sponge, preventing the acid from freely flowing within the battery and improving the charging process.

However, it is crucial to note that AGM batteries, like all sealed lead-acid batteries, are sensitive to overcharging. Overcharging can lead to detrimental effects such as excessive heat generation and reduced battery life. Therefore, it is essential to use a charging system that is specifically designed for AGM batteries and includes features like voltage regulation to prevent overcharging.

Are Agm Batteries Recyclable?

Yes, AGM (Absorbent Glass Mat) batteries are recyclable. These batteries are commonly used in vehicles, uninterruptible power supply (UPS) systems, and other applications. Recycling AGM batteries is important to prevent environmental pollution and recover valuable materials. AGM batteries contain lead, which is a toxic substance, so proper recycling is essential to ensure that lead and other components are safely handled and reused. Many battery recycling programs and facilities accept AGM batteries, and it's recommended to dispose of them through these channels to support environmental sustainability. Always check with local recycling facilities or government guidelines for the specific regulations in your area regarding battery disposal and recycling.

Agm VS. Flooded Battery

AGM (Absorbent Glass Mat) batteries differ from conventional flooded batteries in several aspects. In the provided content, some key distinctions are highlighted:

Sulfation Resistance:

AGM batteries have an advantage in sulfation resistance due to the glass fiber mat. The acid within the mat reduces the likelihood of sulfation, allowing AGM batteries to reach deeper levels of discharge compared to their flooded counterparts.
Internal Resistance and Self-Discharge:

AGM batteries exhibit lower internal resistance and self-discharge rates. This characteristic reduces the need for frequent top charging during long-term storage, a requirement common in flooded batteries.
Charging Speed:

AGM batteries generally charge faster compared to flooded batteries. While both types require charging before storage and maintenance charging during prolonged storage, AGM batteries have a quicker charging rate than flooded batteries.
Cycle Life and Vibration Resistance:

AGM batteries offer advantages in terms of longer cycle life and better resistance to vibrations. The tightly sealed structure of AGM batteries, combined with the internal mat, acts as a damper, making them suitable for applications involving power sports and dynamic movements.
Electrolyte Volume:

AGM batteries require less electrolyte volume compared to flooded batteries, resulting in a lighter overall weight.

One drawback of AGM batteries is their higher cost compared to flooded batteries. The added expense is attributed to the advanced technology and benefits, such as reduced maintenance needs.

Agm Battery VS. Gel

An alternative commonly chosen over flooded and AGM batteries is the Gel battery. Similar to the latter types, Gel batteries are maintenance-free with sealed cells and utilize a recombination process to prevent gas leakage. The distinctive feature of Gel batteries lies in their thixotropic gelled sulfuric acid electrolyte.

When comparing Gel batteries to AGM batteries, one notable difference is the quicker decline in rated capacity for Gel batteries in colder ambient temperatures (below 32 degrees F). Gel batteries also exhibit lower performance in high-rate or starter applications compared to AGM batteries, explaining their absence in power sport applications. However, Gel batteries have an advantage in being more acid limited, contributing to a slightly longer service life in certain applications.

Agm VS. Lithium Batteries

Here are some key differences between AGM batteries and lithium-ion batteries:


AGM Batteries: These are lead-acid batteries that use a glass mat separator to absorb and hold the electrolyte. The lead-acid chemistry is well-established and has been used for many years in various applications.
Lithium-ion Batteries: These batteries use lithium-ion chemistry, which is lighter and has a higher energy density compared to lead-acid batteries. Lithium-ion batteries are commonly used in various electronic devices and electric vehicles.
Weight and Size:

AGM Batteries: Typically heavier and bulkier compared to lithium-ion batteries with similar energy capacity.
Lithium-ion Batteries: Known for their lightweight and compact design, making them suitable for applications where weight and space are critical factors.
Energy Density:

AGM Batteries: Generally have lower energy density compared to lithium-ion batteries. This means they store less energy per unit of volume or weight.
Lithium-ion Batteries: Higher energy density, providing more energy storage capacity in a smaller and lighter package.
Cycle Life:

AGM Batteries: Generally have a lower cycle life compared to lithium-ion batteries. Cycle life refers to the number of charge/discharge cycles a battery can undergo before its capacity significantly degrades.
Lithium-ion Batteries: Typically have a higher cycle life, making them more suitable for applications where frequent charging and discharging occur.

AGM Batteries: Generally require more maintenance, such as periodic checks of electrolyte levels and occasional equalization charges.
Lithium-ion Batteries: Typically maintenance-free, with no need for electrolyte checks or regular maintenance.
Charging Characteristics:

AGM Batteries: Have specific charging requirements, and overcharging can lead to reduced battery life.
Lithium-ion Batteries: Require specific charging profiles, and overcharging can be detrimental to their lifespan. However, many lithium-ion batteries incorporate built-in protection circuits to manage charging and discharging.

AGM Batteries: Commonly used in applications such as automotive starting batteries, uninterruptible power supply (UPS) systems, and some renewable energy storage systems.
Lithium-ion Batteries: Widely used in portable electronics, electric vehicles, renewable energy storage, and a variety of other applications.



Are AGM batteries suitable for all types of vehicles?

AGM batteries are suitable for a wide range of vehicles, including cars, motorcycles, and boats, due to their versatile and durable design.
Can I charge AGM batteries with a regular charger?

While it's possible, it's recommended to use a charger specifically designed for AGM batteries to ensure optimal charging and longevity.
What is the typical lifespan of an AGM battery?

The lifespan of AGM batteries can vary, but with proper maintenance, they can last anywhere up to 10 years.
How do AGM batteries contribute to environmental sustainability?

AGM batteries can be recycled, reducing their environmental impact. Proper disposal and recycling facilities help minimize their ecological footprint.
Can I use AGM batteries for off-grid solar systems?

Yes, AGM batteries are an excellent choice for off-grid solar systems, providing reliable power storage for renewable energy applications.


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