What is An AGM Battery? a Complete Guide

What is An AGM Battery? a Complete Guide

We briefly describe stop/start technology in this blog post and list the benefits of AGM batteries.

Absorbent Glass Mat car batteries (In the 1980s, AGM) were created for military use. They are perfectly suited for today’s modern cars, which are frequently heavily loaded with sophisticated electrical systems, energy-consuming devices, and accessories due to their high performance and improved electrical reliability.

To help you choose the best battery type for you, we’ve expanded on What is an AGM battery in the section below. And here is Gel Battery.

What is An AGM Battery?

Batteries made of absorbed glass mats are built differently than conventional flooded batteries. This write-up covers mainly the Concorde Sun-Xtender AGMs, but also applies to most other brands of deep cycle AGM batteries.

AGM batteries, also known as starved electrolyte batteries, consist of two plates that have been saturated with battery acid to about 95% of their maximum capacity and a thin, ultra-fine fiberglass mat in between. The mat is then lightly compressed and stuffed between the plates before being welded or soldered into position. Plates and mats are nearly vibration-proof because they are packed closely together.

Power, weight, safety, and reliability were the most important factors when designing military aircraft in the 1980s, which led to the development and introduction of AGM (Absorbed Glass Mat) sealed battery technology in 1985.

What is An AGM Battery? a Complete Guide

The batteries used in Concorde AGM aircraft are valve-regulated sealed lead-acid batteries, also known as VRSLAB or VRLA (valve-regulated lead-acid). AGM batteries are now produced by a number of companies, but Concorde was the first to create the technology for non-military commercial applications.


  • Up to 2x longer life than a standard flooded batteries
  • Designed for harsh climates and demanding conditions
  • Handles high electrical loads
  • Quickly recharges and extends cycle life
  • Ideal for start-stop applications
  • Vibration resistance
  • Non spillable and maintenance-free
  • Greater mounting flexibility


  • Higher initial investment

How Do AGM Batteries Work?

An AGM battery’s superpowers are a result of two ground-breaking improvements made to Plant’s original design as well as numerous minor adjustments that fundamentally increase the capabilities of car batteries.

  • Water that has evaporated is kept inside the battery case by a valve.

This might only sound like the opposite of one-way valves on coffee bean bags at first. But the key to an AGM’s long lifespan is this simple trick. Here’s how.

What is An AGM Battery? a Complete Guide

Lead, sulfuric acid, and water still make up its basic chemistry. The lead plates only contain water and lead sulfate after the acid molecules move to the lead plates when you draw power. For the paste on the plates to interact chemically, you are removing the sulfuric acid from the solution. When the battery is charged, this procedure is reversed.

Electricity can split water molecules into hydrogen and oxygen gases, but there is always a chance that some water will leak out. The electrolyte remains more acidic than usual as a result of the loss of those water molecules, weakening the potential strength of the chemical reaction on the plates and ultimately reducing the life span. Learn How to Fill Lead Acid Battery? Lead Acid Battery Watering Tips

These gases cannot escape due to the AGM’s valve. except if the battery is overcharged. The current must pass through everything it can when an AGM is charged with the incorrect charger. More water molecules would be broken up as a result, which would result in an interior gas buildup. The safety mechanism then engages, releasing some gas to lessen the pressure that has accumulated inside the battery.

  • The glass mats (GM) in AGM (absorbed glass mat) batteries are made of fiberglass.

In order to cushion the lead plates, ultra-thin glass fibers absorb all of the electrolytes (water and sulfuric acid). AGM batteries store their charge in moist sponges that are coated with lead plates rather than the free-flowing liquid found inside conventional car batteries. The glass mats’ complete coverage makes it easier to summon more power from an AGM battery — and makes it easier to recharge.

The AGM battery surpasses standard batteries in terms of strength, speed, longevity, and durability.

Are AGM Batteries the Same as Valve Regulated Lead Acid Batteries?

AGM batteries may also be referred to as VRLA batteries, which stand for valve-regulated lead acid batteries. One variety of VRLA batteries is the AGM battery. The crucial feature of VRLA batteries is that a unique valve is built into them to stop gases from escaping the battery’s casing.

What is An AGM Battery? a Complete Guide

So what makes that significant? Lead acid batteries generate electrical energy by converting chemical energy that has been stored. This is done through a series of chemical reactions that take place between the battery’s plates and the electrolyte. In the course of this procedure, the electrolyte’s water is divided into hydrogen and oxygen gases.

A flooded battery may experience some water loss as a result of evaporation in that situation. Because of this, flooded batteries need to occasionally have distilled water added to them to keep them from overtime becoming too acidic, which will reduce the battery’s overall lifespan.

Due to the complete sealing of a VRLA battery, no gas can escape, allowing it to recombine into the water during the charging process. This preserves the electrolyte’s proper chemical concentration, giving the battery a longer life.

Here are other comparisons of batteries:

Can AGM Batteries Be Used for Deep Cycle Applications?

The ability of AGM batteries to serve as both SLI (Starting, Lighting & Ignition) and deep cycle batteries are one of their distinctive qualities. Your car, truck, or RV’s engine will start using SLI batteries. They are designed to deliver quick, intense bursts of energy.

Deep cycle batteries are made to deliver shorter bursts of power that are more dependable over an extended period of time. Deep cycle batteries are frequently used in equipment like floor scrubbers and golf carts. They are frequently used as the house battery in boats and RVs.

Can You Charge An AGM Battery With a Regular Charger?

What is An AGM Battery? a Complete Guide

AGM batteries cannot be charged with a standard battery charger, which is an important point to remember. This is due to the fact that AGM batteries require different charging procedures than conventional flooded batteries. AGM batteries can’t withstand the high charging speeds used by conventional battery chargers and require a slower, more steady charge than flooded batteries.

You risk undercharging or overcharging an AGM battery if you use the incorrect kind of charger. The battery’s capacity to accept a full charge may be decreased by sulfation on the plates brought on by undercharging. Overcharging cooks the components inside the battery, which can shorten its lifespan or kill the battery entirely.

When looking for a battery charger, make sure the model you choose is appropriate for the lead acid battery voltage and chemistry of the battery you intend to use it with. For instance, if you have a 12-volt AGM marine battery, you need a charger that is compatible with 12-volt AGM batteries. There are settings on a lot of modern chargers for various lead acid battery types.

Conclusion: AGM Battery

AGM batteries are more expensive than flooded batteries, so they may not be the best option for all applications. But they are the preferred battery for many applications due to their design and safety features.

Vehicles with high electrical demands and seasonal vehicles, such as ATVs, Snowmobiles, UTVs, and Powersports vehicles, are the ones that most frequently use AGM Batteries because they need to have higher power, be resistant to acid spillage, and be vibration-resistant. An AGM battery is a great option if you require a lot of power, want to be able to store your car in the off-season, and want a battery that requires little to no maintenance.

Here is more information about lead acid batteries:


How Do I Know If My AGM Battery Needs Replacing?

If a fully charged AGM battery tests more than 20 percent lower than the fully charged voltage level, it’s probably due for replacement. This is typically a sign of battery sulfation, damage from overcharging or undercharging, or battery aging.

Should I Keep My AGM Battery Fully Charged?

Keep the battery fully charged, as often as possible. No, these batteries do not develop a “memory” like some nickel-cadmium-based batteries. The life of AGM batteries can be shortened and damaged by deeply discharging a battery and leaving it there.

One thought on “What is An AGM Battery? a Complete Guide

  1. It’s great that you mentioned how AGM batteries are the preferred battery for many applications due to their design and safety features. I was shopping for some batteries earlier and I saw a lightweight AGM battery displayed on one of the shelves. It seems very useful and robust, so I’d like to know more about it.

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