What is an AGM Battery?

What is an AGM Battery
Image credit: autobatteries.com

If you are wondering what is an AGM battery? Then, you are at the right spot. We will tell you about this long-enduring power unit, from its components to best-use applications.

ABSORBENT GLASS MAT(AGM)  is a high-level lead-acid battery that gives better power that meets the higher electrical demands of the present vehicles. It is incredibly resistant to vibration, wholly fixed, non-spill, and support-free.

AGM offers better cycling execution, insignificant gassing, and corrosive spillage than regular lead-acid batteries. In this article, we will look at the following:

  • How AGM battery started
  • How it works
  • Its uses
  • Its efficiency
  • Differences between AGM and regular car batteries

So, let us get started on this highly efficient power unit without further ado.

AGM Battery – A Better Performing Cell

The main highlight of this new cell technology is the longer endurance. Glass mats, padding the super dainty lead plates, will crush like a wipe. Hence, producers can grind more glass mats and lead into one battery.

More lead equals more power, and that crunch factor implies the battery’s internal parts are pressed firmly.

AGM batteries have valves directing how much hydrogen and oxygen gas evade during charging. They fall under a more extensive classification of valve-controlled, lead-acid (VRLA) batteries.

Created in the last part of the 1970s, AGM batteries generally filled in as reinforcement power for pay phones and early PC rooms.

Their utilization extended over time to incorporate bikes, military, airplanes, submarines, and power banks for workplaces.

Presently, they’re appearing in regular vehicles and trucks. So, what is an AGM battery, and how does it fare against regular cells? To answer this, let us first journey through history.

But before that, we recommend you read our top picks for the best battery brands. You might find the right one for your car.

How They Came to Be?

During the 1970s, the sealed lead acid (SLA) batteries debuted. Until this point, lead acid batteries utilized a wet-cell configuration, in which a lead composite lattice was lowered in acid.

SLA batteries use a separator immersed with electrolyte, resulting in a battery that can work in any direction without the gamble of spilling.

AGM (Absorbed Glass Mat) came to be in 1980,  finding its first military airplane use in 1985. Engineers adopted it because of its power, weight, security, and dependability.

The Concorde AGM batteries are VRSLAB (Valve Regulated Sealed Lead-Acid Battery), sometimes referred to as VRLA (Valve Regulated Lead-Acid). A few makers currently produce AGM batteries, yet Concorde was quick to foster the innovation for non-military use.

The most widely recognized SLA batteries are the gel and AGM assortment. A woven mat of glass fiber in the electrolyte acts like the separator in AGM batteries.

This configuration results in quicker charging (multiple times faster than lead acid batteries) and on-request high burden flows. Also, they are more impervious to issues like sulfation and can be put away for more extended periods without charge.

AGM batteries are vibration safe, making them the best for auto-sports like NASCAR.

How an AGM Battery is Built?

Further in answering your question, what is an AGM battery? It is only proper to examine how manufacturers make them, although briefly.

This power cell has a dainty, super fine fiberglass mat sandwiched between the plates. The mat in the middle of between the plates forms a compact, welded/bound setup. Since the plates and mats are stuffed genuinely close, they are practically insusceptible to vibration.

What is an AGM Battery? – How It Works?

Knowing how these cell works are crucial to answering what is an AGM battery. It has key differences that give it the extra boost and endurance.

The primary feature of an AGM battery is the ultra-thin glass mat, also known as the AGM separator. Manufacturers sandwich this fiberglass mat between the lead plates, soaking up the electrolyte.

With such a design, the electrolyte suspends in a dry state rather than in a free-flowing form you find in traditional flooded batteries.

The glass mat provides a much larger surface area for the electrolyte’s reaction with the battery plates. This setting results in a fast reaction between the plate material and the sulfuric acid.

At the start of this article, what is an AGM battery? We mentioned that they are valve-regulated lead-acid power cells. So, what function does the valve perform?

First, the electrolyte is a blend of water and sulfuric acid. As a result, charging produces hydrogen and oxygen.

Losses come into play when these gases leave the battery, hence the need for the valve to stop them. The result is the reabsorption of the gases into the electrolyte.

Nevertheless, there could be a pressure overdose, especially when overcharged. When that happens, the valve releases some gases to reduce the pressure to a safe limit.

This functionality further prevents physical damage to the power cell, resulting in longevity.

Uses of AGM Batteries

The following are the common uses of AGM batteries:

  • Provision of power to military aircraft, submarines, cars, trucks, etc.
  • Provides a powerful burst of starting amps
  • Used in renewable systems like wind and solar
  • Used in robotics and some ATVs

Critical Differences Between AGM Batteries and Car Batteries

In furtherance to answering your question, what is an AGM battery? It is crucial to point out how it differs from regular car batteries.

AGM vehicle batteries enjoy several advantages over the latter, including:

  • More power per battery
  • Quicker re-energizing
  • More strong development
  • More secure to deal with
  • Extraordinary valves safeguarding the battery’s life expectancy

Throughout their life expectancy, AGM batteries can turn over a motor multiple times. That is numerous times more than the traditional battery.

Furthermore, AGMs re-energize quicker than regular batteries. Starting your vehicle slightly depletes the cell before the alternator dominates.

At the point when it does, the alternator re-energizes the battery — and keeps every one of the electrical parts running in the vehicle.

Due to their assimilated mats, AGMs endure shaking and vibration better than regular batteries. Their spill-proof also means the guidelines are loosened about moving them via air or road. This could seem as though promoting publicity, and it’s simply science.

AGM – Deep Cycle or Not?

Because a battery is AGM doesn’t make it a deep cycle battery. A few organizations, like Optima, have embraced AGM for beginning batteries and other non-deep cycle applications.

Deep cycle cells can discharge up to 80% and charge up quickly. They are long-endurance power cells. Principally, the plate thickness makes a battery deep cycle, not whether it is overwhelmed, gelled, or AGM.

Popular examples of deep cycle batteries include the Concorde Sun-Extender, the Concorde Lifeline, Chairman, etc.

The Concorde SunXtender batteries are similar to the Concorde Lifeline, Chairman, and other Concorde AGM batteries. The significant difference is that the Sun-Extender batteries have bolt-on terminals rather than the normal post type. Bolts on terminals give a significantly more dependable configuration.

Battery Efficiency

Understanding efficiency is crucial for high charge or release rate applications. The inner construction of a battery affects its general charge/release productivity and capacity to convey high flows without critical drops in voltage.

So, even as we answer your question, what is an AGM battery? The following affect the efficiency of AGM batteries:

Battery Internal Resistance Losses:

Inefficiencies from interior construction appear as resistance, increasing temperature when intensely charged or released for some time. For standard batteries, resistance is about 10% to 15% but can go up to 25%.

Also, the resistance varies as the battery ages, most notably on construction. Less expensive batteries have thin plates, which are less efficient.

Gel batteries are better at roughly 12% to 16% inner resistance. As a result, it has around 115 amp-long periods of charge for every 100 amp-hours.


Any current that does not go into charging the battery transforms into heat. For that reason, a few batteries, including more seasoned overflowed batteries and some non-deep cycle AGMs, can get warm.

While a bit of warmth is nothing to worry about, excessive heat is hazardous. It could lead to swelling and, in extreme cases, explosion. You must monitor your batteries.

How to Prolong AGM Battery Life?

Despite the benefits AGM battery give, it is essential to appropriately keep up with them to augment their life expectancy. Luckily, you will not have to do much in this regard.

First, ensure you charge them adequately and monitor the temperature. Lead acid batteries can work in a broad range of temperatures, the best range between 72°F and 82°F.

Charging the battery after use or after delayed capacity is the principal approach to expanding its life expectancy.

When to Use AGM Batteries

AGM batteries are not an ideal decision for all applications. Nonetheless, their security and configuration highlights make them suitable for some applications, including:

  • Where you can’t have vapor or hydrogen, like in inadequately ventilated regions, or where exhaust might cause corrosion, for example, repeater and cell locales.
  • Where protection from shock and vibration is significant.
  • Where spilled corrosive from releasing, tipped, or broken batteries can’t go on without serious consequences.
  • Where the batteries might be liable to freezing (- 40 degrees F or lower).
  • Whenever you want a dependable and wholly fixed battery for security or ecological reasons. It could be for wheelchairs, clinical backup power, inside RVs, PC room UPS frameworks, or encased spaces in boats.

Pros and Cons of AGM Batteries

Before we close the book on this what is an AGM battery article, let us look at a few pros and cons.


The following are the pros of using an AGM battery:

  • Long-lasting

AGM batteries last twice as long as traditional cells. Even when not in use, their low self-discharge rate gives them better longevity.

  • Lightweight and Durable

The electrolyte in AGM batteries does not expand like in a flooded lead acid cell, thanks to the glass mat. Also, it has a low weight because of the less electrolyte.

  • Resistance to freezing

The absence of liquid expansion gives AGM cells the ability to withstand freezing. While it carries no charge while frozen, there will be no cracks or damage to the plates.

  • More start cycles

These peculiar power cells can start an engine over 600,000 times which is 3x more than the traditional batteries.

  • Less internal resistance

As seen earlier, AGM cells have less resistance, about 12%. The low figure means they can quickly deliver power and give rapid energy to start the car’s engine.

  • Quick recharge

The recharging speed of AGM batteries is 5x faster than conventional cells, which invariably leads to longevity.

Also, this cell can discharge up to 80% of its capacity without damage, and flooded batteries are only capable of 50% depth of discharge.

A low depth of discharge makes a battery capable of deep cycle applications. On that account, AGM has extensive usage in deep cycle conditions, including marine vessels.

  • Vibration resistance

The fiberglass mats in the electrolyte can dampen shocks, thereby eliminating any vibrations.

  • Maintenance-free

The non-spillable nature of AGM batteries means they do not need any watering service. Regardless of position, the fiberglass prevents the electrolyte from spillage. With such a design, flexibility poses no challenge during mounting.


AGM batteries have a few setbacks, including:

  • Overcharging

Overcharging AGM batteries will damage them, as they have a lower tolerance than traditional flooded batteries.

  • Cost

Due to their construction, AGM batteries are more expensive than conventional cells. Sometimes, the cost is double that of traditional batteries, resulting in limited usage.

Final Thoughts

AGM batteries have much better protection from vibration and shock because of their development than most flooded batteries. The plates press in with the glass mat, diminishing plate development and vibration.

AGM batteries can endure freezing. Though you will get next to zero results from a frozen battery, the cold will not destroy the battery or break the case.

Frequently Asked Questions

Before we end this article, let’s attend to a few frequently asked questions.

Is an AGM battery the same as a Gel cell?

These two power units differ in how they hold the electrolyte. The AGM cell holds the solution using the absorbent glass mat, while the Gel battery uses a chemical agent, commonly silica, to suspend the solution.

Can I use the regular charger on an AGM battery?

As mentioned earlier, AGM batteries are sensitive to overcharging. On that note, it is crucial to use specially designed chargers when powering them up.

Can I use AGM cells for deep Cycle Applications?

Thanks to its low depth of discharge, you can use the battery for deep cycle applications.

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