AGM batteries are a type of lead-acid battery, first produced in 1972. Over time, AGM battery technology has become very mature and is widely used in people’s daily lives and in production. If you would like to know more about “what is an AGM battery’, please continue reading.

What Does AGM Battery Mean?

AGM batteries refer to valve-regulated lead-acid batteries (VRLA) that use an absorbent glass mat separator to keep the electrolyte separated from the plates. Unlike flooded lead-acid batteries, AGM batteries are not only sealed lead-acid batteries (SLA) but also known as starved electrolyte batteries. This is because the AGM technology absorbs the electrolyte and retains it within the glass mat. Thus, the plates are not soaked in liquid but remain moist at all times. Therefore, you do not need to periodically water AGM batteries, and they can be installed and used in any orientation.

How Do AGM Batteries Work? 

AGM batteries charge and discharge through a chemical reaction between the positive and negative plates. During discharge, the lead of the positive and negative electrodes reacts with sulfuric acid, converting into lead sulfate and water, while releasing electrical energy. During charging, lead sulfate is converted back into lead, lead dioxide, and sulfuric acid is regenerated.

Advantages Of AGM Battery

Sealed Design: AGM batteries are sealed lead-acid batteries, which reduce the emission of gases such as hydrogen, making them more environmentally friendly.

Easy Maintenance: The sealed design eliminates the need for regular checks and refilling of electrolyte, significantly reducing maintenance efforts.

Low Risk of Leakage: The electrolyte is absorbed in the glass mat, so there is no concern about leakage.

High Power Density: AGM batteries have low internal resistance, support rapid charging and discharging, and can handle high-load, instantaneous, large current discharges.

Flexible Installation: With the electrolyte immobilized and the unit sealed, AGM batteries can be installed in various orientations without the risk of leaking.

Disadvantage Of AGM Battery?

High Cost: Compared to traditional flooded lead-acid batteries, its production cost is higher.

Strict Charging: AGM batteries cannot tolerate overcharging or deep discharging, which can significantly shorten their lifespan.

Capacity Issue: Its capacity gradually diminishes over extended usage cycles.

Low Energy Density: Compared to other advanced battery technologies, it has a lower energy density, resulting in larger volume and more occupied space.

How Long Do AGM Batteries Last?

The expected lifespan of AGM batteries typically ranges from 3 to 7 years. However, this is just a rough estimate. The actual lifespan is influenced by various factors, including the number of charge-discharge cycles, the frequency of deep discharges, charging conditions, usage habits, storage conditions, and battery maintenance. Even the quality of materials used by the manufacturer can have an impact.

What Are AGM Batteries Used For?

Sealed AGM batteries offer good safety performance, are easy to maintain, and are quite reliable. You can use them for:

Start-Stop Systems: AGM batteries can provide a powerful instantaneous starting current, capable of handling the high loads of frequent vehicle starting and stopping. Therefore, they are widely used in motorcycles, cars, trucks, recreational vehicles, and golf carts for activating engines.

Deep Cycle Applications: AGM batteries can be used as deep cycle batteries, providing stable power to various systems and devices. For example, they serve as uninterrupted power supplies in commercial and residential buildings, data centers, as well as backup power for emergency lighting and security systems, and also as power sources in recreational vehicles and boats.

Solar Energy Storage Applications: AGM batteries are also used in wind and solar energy storage systems. They store the electricity generated by these systems for use at night or on cloudy days.

car start stop battery

car start stop battery

How To Charge An AGM Battery?

Using the correct method to charge AGM batteries can help extend their lifespan.

First, you need to use a charger specifically designed for AGM batteries.

Second, carefully inspect the battery and charger to ensure they are undamaged and free from corrosion.

Next, connect the positive and negative terminals of the charger to the corresponding terminals of the battery, ensuring a secure connection.

Finally, switch the charger to a mode suitable for AGM batteries. During charging, you should still periodically check the battery and charger to ensure they do not overheat and remain in a safe condition.

Types of Rechargeable Battery

Rechargeable Battery

AGM Vs. Other Battery

AGM Battery Vs GEL Battery 

They are both types of sealed lead-acid batteries, but they differ in the way they immobilize the electrolyte. AGM batteries use an absorbent glass mat to fix the liquid electrolyte, while GEL batteries use a gel-like electrolyte. They generally require minimal maintenance. The cost of AGM batteries may be slightly lower than that of GEL batteries, but GEL batteries theoretically have a longer lifespan.

AGM Battery Vs Lithium Battery 

AGM batteries are a type of lead-acid battery, which, along with lithium batteries, are two common types. AGM batteries cost less, but they have a lower energy density compared to lithium batteries. Consequently, their size, weight, duration, and lifespan are inferior to those of lithium batteries. Lead-acid batteries are more commonly used in applications requiring high instantaneous currents, while lithium batteries are often used for deep cycle applications that require long-term power supply.

Lithium Battery VS. Lead Acid Battery

Lithium Battery VS. Lead Acid Battery

What Is The Difference Between EFB And AGM Battery?

EFB batteries are Enhanced Flooded Batteries, a type of lead-acid battery that uses polyester fiber separators to stabilize the electrolyte. This improves their cycle life and makes them suitable for start-stop technology. However, AGM batteries still surpass EFB batteries in terms of charge-discharge cycles, vibration resistance, and energy output.

What Is The Difference Between AGM And Standard Batteries? 

AGM batteries are completely sealed lead-acid batteries, internally using absorbent glass fiber to immobilize the electrolyte, requiring virtually no maintenance, and can be placed in any orientation.

In contrast, standard batteries have a vent to expel gases, and their internal electrolyte is fluid, requiring you to regularly check and replenish water.

Overall, AGM batteries offer better performance and require no maintenance, whereas standard lead-acid batteries are suitable for cost-sensitive applications.

Is It Worth Getting An AGM Battery? 

Whether it is worth it depends on whether the AGM battery meets your expectations and solves your problems. You can preliminarily judge its “worth” based on its advantages and disadvantages, such as its low maintenance requirements, strong vibration resistance, instant start current, faster charging speed compared to standard lead-acid batteries, and a lower self-discharge rate. However, its cost is higher than traditional lead-acid batteries, and it is more sensitive to charging, with overcharging easily damaging the battery.

When you consider factors such as budget, needs, and battery performance carefully, your experience will give you the answer.


How Do I Know If My Battery Is AGM?

You can confirm whether a battery is of the AGM type by using the following methods:

Look at the battery’s label or manual to see if it is marked with “AGM” or “Absorbed Glass Mat.”

Check if the battery’s appearance is sealed and lacks any refillable water vent caps.

Consult the battery manufacturer or retailer to obtain precise information.

Lead Acid Battery

Lead Acid Battery


Are AGM Batteries Deep Cycle? 

In addition to being used as starter batteries, AGM batteries can also be used as deep cycle batteries, applicable in fields such as electric vehicles, golf carts, marine vessels, and solar energy.

Can You Charge An AGM Battery With A Regular Charger?

It is best to charge AGM batteries with a dedicated charger. For ordinary chargers, you need to check whether the output voltage meets the charging requirements of AGM batteries. Additionally, closely monitor the charging process to avoid overcharging.

What Does AGM Stand For In Batteries?

AGM stands for Absorbed Glass Mat, which is a type of lead-acid battery.

What Is A 12V AGM Battery?

A 12V AGM battery refers to a lead-acid battery that uses absorbent glass mat technology and has a 12-volt output. It is a versatile and highly reliable power solution.

Are AGM And GEL Batteries The Same? 

Although AGM and GEL batteries are both types of lead-acid batteries, they are not entirely the same. The main difference lies in the fact that the electrolyte in AGM batteries is liquid and is immobilized using absorbent glass mat separators, while the electrolyte in GEL batteries is gel-like.


AGM batteries are a type of lead-acid battery widely used in our daily lives. Understanding their definition, advantages and disadvantages, and charging methods can help us extend their lifespan.