By Erik Watkins

What Does AGM Battery Mean? How Does It Work?

Last updated: May 11, 2023
What Does AGM Battery Mean

You’ve probably heard people say that long-lasting battery life is the pivotal aspect when owning a car. If your vehicle doesn’t have an operating battery or fails to retain any charge, how could you rely on it as your trusted partner on the road?

AGM batteries can supply a significant amount of power for your engine. Nothing seems to beat a car with super strength and outstanding performance. 

To ensure that everyone knows what an AGM battery is and how it helps, let us explain this in detail so that you can understand the greatness of using one in your car.

Beyond that, more lesser-known facts about an absorbed glass mat battery lie here. Stay tuned

What Does AGM Battery Mean?

AGM batteries are advanced lead-acid batteries operating based on an “absorbed glass” mechanism. Their work is to deliver more power to satisfy the increased electrical demands of modern automobiles.

Absorbent glass mat batteries (AGM batteries) in cars and trucks have two main tasks: run electronics or store power over the long run, and provide starting amps’ powerful bursts. 

They were invented in the 1970s as backup power for computer rooms and telephone boxes. From the 1980s, this type of batteries widespread in multiple vehicles: aircraft, military, motorcycles, and submarines. Primarily, AGM works wonders in modern trucks and cars, alongside energy-consuming devices and exquisite electrical systems.  

Indeed, more and more cars use maintenance-free automotive batteries and stop-start battery technology.

How Does AGM Battery Work?

Each battery has a glass mat separator made from peculiar fiberglass materials. It’s responsible for wicking the electrolyte solution (water and sulfuric acid) inside the plates. As such, it keeps the electrolyte solution in a suspended and dry state. The glass mats’ coverage produces more power and speeds up recharge. 

Once AGM runs, electrolytes move from the fiberglass mat to the plates, creating full capacity without spilling. This occurs even when the battery case gets ruined or tipped on its side. 

How Does AGM Battery Operate

The chemical mixture inside AGM includes sulfuric acid, water, and lead. While the power draws, the acid molecules transfer to the plates, leaving sulfate and water. Until the sulfuric acid separates from the solution, a chemical reaction occurs on the plates. This process is reversed while recharging the batteries. 

The AGM’s superpower derives from Planté battery technology and top-notch designs. First off, lots of valves hinder evaporated water from oozing outside. Thus, this way helps prevent risks and thus, extend the AGM’s life. 

Once you overcharge the battery, too much oxygen and hydrogen gases release due to H2O splits, causing water loss. This increases electrolytes’ acidity, mitigates the chemical reaction’s capability, and shortens the battery’s life. That’s when the safety mechanism kicks off, letting gas escape and alleviating the pressure inside the battery.

What Are The Pros & Cons Of AGM Battery?

As fascinating as AGM batteries are, many prefer equipping them for their vehicles. Still, AGM has its drawbacks and advantages. Go for a short analysis, and it would help if you compare AGM with other batteries on the market.


AGM looks like top-notch batteries which require no maintenance during use or watering service. They often stick to off-grid and environmentally-friendly renewable power systems such as solar and wind power. 

Overall, with minimal gassing and a unique design, AGM batteries could operate and produce power efficiently. The liquid electrolyte flows freely making the whole battery versatile and powerful.

Also, the separator suspension hinders the vibration effectively. Thus, they’re worth installing inside ATVs, snowmobiles, and other Powersports to deal with uneven surfaces.  

They get on well with the most start-stop vehicles. They are perfect for vehicles requiring off-season storage as they keep their charge well, have long battery life, and are resistant to harsh conditions. 


First off, AGM batteries only work with the correct battery chargers. And they can’t reach the best performance without a full charge. 

Beyond that, they need lots of care. Under or overcharging always weakens the batteries’ performance and life. Overcharge may ruin the whole battery and kill it soon. Meanwhile, undercharging creates excess sulfation on the plates, impeding the full charge ability.

AGM works best under the limited discharge of a maximum of 50% battery capacity

What Are The Differences Between AGM Battery & Conventional Battery?

AGM batteries outweigh traditional batteries (or flooded batteries) regarding recharging speed, lifespan, weather resistance, construction, etc. Here are some advantages that might catch your attention in no time:

More Weather Resistance

Thanks to the solid construction, internal resistance, and durability, AGM batteries can deal well with extreme cold and heat. This is an ability that conventional batteries can’t live up to.

More Rapid Recharging Process

The recharging speed of AGM is faster, 5 times more than conventional lead-acid batteries. Furthermore, the AGM batteries could hold their capacity longer while not being used. They can also recover if drained utterly.

Longer Lifespan

Because of the peculiar valves, AGM can release exceeding gasses if needed or overcharged, and last their life longer

Beyond that, the unique construction of an AGM battery makes it stay three times longer than a regular car battery. A durable battery is always a cost-effective choice over the long run that anyone desires.

AGM Batteries Support More Starts

In particular, an engine with AGM can start up to 60,000 times, over three times more than a regular battery. The starting process becomes faster and more effective. Indeed, AGM is an outstanding battery replacement if you no longer use normal options.

Advanced Structure And Unique Design

AGM batteries contain plates and separators made from particular fiberglass. On the flip hand, the regular lead-acid batteries are a fixture in trucks, cars, boats, and RVs. Their lead plates and separators inside are all packed in a solid casing filled with electrolytes.

AGM batteries also beat the flooded option as they’re maintenance-free, while the standard battery’s maintenance is compulsory.

Last but not least, AGM possesses the start-stop vehicle technology which interests many drivers.

More Shaking And Vibration Resistance

Start process just costs your battery a minor amount of electricity. Afterward, the alternator will then take over to charge your battery. They work together to ensure all car components operate correctly. 

Of note, AGM batteries can absorb mats. Thus, they incredibly alleviate vibration and shaking, adapting well to boats and watercraft.


As the plate separators hold the electrolyte, AGM batteries are spill-proof, enabling you to mount them in various positions that flooded options can’t work.

As a spill-proof item, AGM can be transported by road or air easier than the regular one (because of the general regulation).

Generate More Power

They also have a more extensive and unique design, generating higher voltage output and power. 

Not to mention that AGM batteries push the starting process faster and feature extra power for various devices like fuel-saving start-stop systems, backup systems, cameras, and touchscreens, to name a few.

Video: What is an AGM Battery?

Key Takeaways

We have rounded up many lesser-known facts surrounding AGM batteries, including the meaning of AGM batteries.

Versatile and state-of-the-art, they contribute much to any engine and vehicle. Considering buying one may be the next idea raising in the car owners’ minds. 

Give this far-out battery type a try. We bet what you receive will be more than you assume. If you find this writing informative, share it with others at once

Automotive Mechanic at PowerAll

With 7 years experience in management positions leading automotive mechanics at PowerAll, Erik Watkins wishes to share useful knowledge and information about automotive mechanical equipment.


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