Battery 101: AGM vs. GEL Technology. Agm technology car battery

The Complete Guide to AGM Batteries

You’ve heard the term AGM battery before and may even know that it stands for Absorbent Glass Mat. But, what does Absorbent Glass Mat (AGM) actually mean and how does that enhance the battery’s performance over standard lead acid batteries?

Let’s review some basics of the SLA (sealed lead acid) battery construction. All SLA batteries are comprised of lead plates (positive and negative) and electrolyte that are then arranged into “cells” and placed into a battery case. Some of these batteries are also valve-regulated, which allows for the escape of minor amounts of gas that occurs during the recombination process during charging. Although these batteries allow gases to escape, they are spill-proof batteries (sometimes called valve regulated lead acid or VRLA), and allow for safe operation in almost any position (the only limitation is they are not recommended to be used upside down). Because they are sealed, you don’t need to add electrolyte after the manufacturing process, and any gases that are generated go into a recombination cycle.


In AGM type batteries, the construction follows the same basics as standard SLA, with the addition of a fiberglass mat that is placed between each negative and positive plate to absorb the electrolyte. Since the mat acts like a sponge with the electrolyte, the battery becomes non-spillable.

The AGM battery holds the electrolyte in place and works by allowing the electrolyte to be passed through the fiberglass mat, creating maximum surface area for the electrolyte to touch the plates without it flooding the battery with too much fluid. AGM batteries contain only enough electrolyte to keep the mat wet and if the battery is broken no free liquid is available to leak out. This allows for less electrolyte in the battery while still providing the same energy as traditional SLA batteries.


When most people think of AGM batteries, they likely think of deep cycle battery applications. However, not all AGM batteries are deep cycle. While a popular choice for deep cycling, as an AGM battery has a depth of discharge (DoD) of 80% versus a standard flooded battery which has a DoD of 50%, it is also a popular choice for starter batteries. This is because it has low internal resistance and can provide high current loads quickly. AGM batteries are also being used as start-stop batteries in modern cars, this is due to flooded batteries not being robust enough to handle the repeated cycling in start-stop applications which can cause the battery to fail after only a couple of years use.

For example, at Power Sonic we offer our AGM technology in both deep cycle AGM batteries (the PDC line) and as a popular option in our PowerSport family (Super Sport, Ultra Sport AGM, and our Stop-Start AGM lines). However, AGM is also the technology we use in our general purpose (PS) and long life (PG) families of products as the Absorbent Glass Mat separator maximizes the surface area of the electrolyte improving battery performance.

Each cell in an AGM battery has 2 volts so AGM batteries are available in a variety of voltages including popular 6V and 12V models.


One of the advantages of an AGM battery is they can be charged up to five times faster than a standard flooded battery. As with all sealed lead acid batteries, AGM are sensitive to over-charging, we recommend this guide to charging sealed lead acid batteries to ensure get the most out of your AGM battery.


Yes AGM batteries are recyclable. than 98% of an AGM battery can be recycled. We in the battery industry are very proud of the fact that lead acid batteries are one of the most highly recycled products on the planet. AGM batteries are environmentally friendly and easy to recycle, they can be recycled at almost all recycling centers, along with many automotive outlets and thousands of other locations.


There are many benefits of AGM technology over its older flooded battery construction. One big benefit of the fiberglass mat is that since the mat holds the acid, the battery is less likely to sulfate. This characteristic is what allows it to reach a deeper DoD than it’s flooded equivalent.

The lower internal resistance of the AGM battery also has a lower self-discharge rate and therefore doesn’t require a topping charge as frequently as a flooded battery would in long term storage conditions. It is important to note that AGM batteries still must be charged before storing and will require maintenance charging while in long term storage but will charge faster than a flooded battery.

Some advantages that AGM has over flooded batteries (as well as faster charging) are increased cycle life and vibration resistance. This is because the combination of the tightly packed AGM battery and the mat inside act as a damper, which are characteristics that lend nicely to power sport applications. Another benefit of the mat is that the battery requires less electrolyte than flooded batteries, which decreases its weight.

However, one of the down sides to the AGM battery is its cost – at slightly higher than flooded, you will pay more for a battery that doesn’t need to be maintained in the same way a flooded battery does. In fact, cost is one of the reasons flooded batteries are still commonplace (usually seen more in motorsport applications).


Another popular alternative to flooded and AGM type batteries is the Gel battery. A Gel battery is still maintenance-free, its cells are sealed, and it uses a recombination process to prevent the escape of its gasses. What varies with a Gel battery is the electrolyte itself is a thixotropic gelled sulfuric acid.

When comparing a Gel battery to an AGM battery, you will see that the Gel battery’s rated capacity will decline much faster than an AGM battery’s as the ambient temperature get colder (below 32 degrees F). A Gel battery is also does not perform as well in high rate or starter applications as an AGM, which is why you don’t see Gel power sport batteries. On the plus side for Gel, it is more acid limited, giving it a slightly longer service life in some applications. Power Sonic offers Gel batteries in our DCG (Deep Cycle Gel) and our 2-volt OPzV Tubular Gel lines.

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There are many differences between AGM and lithium batteries. When it comes to choosing the right battery for your application, you need to understand exactly what you are looking to get out of the battery. Is it a deep cycling application, a high rate discharge application or a float standby application? Does the application already have a built in charger for a specific chemistry? What is your budget? etc.

We at Power Sonic have put together a comprehensive guide to the differences between sealed lead acid batteries and LiFePO4 batteries, this should be able to help you to see whether AGM is the better choice for your application.

To summarize, depending on the application and your budget, you will find the AGM battery to be the more superior battery over flooded battery types due to its lower weight, lower maintenance, and overall enhanced performance. You will also find AGM to be a popular choice over the Gel batteries as they are much more common and usually less expensive. The battle between AGM and lithium batteries will depend on your application and what you are looking to get out of the battery.

If you have any questions about which battery is more suitable for your application, please feel free to call or email us.


Find the right battery for your application today. Many of Power Sonic’s wide range of sealed lead acid batteries utilize the latest in AGM technology.

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Battery 101: AGM vs. GEL Technology

The technology used to create batteries has come a long way since the time of glass cells and wooden encasements. Now we have specialized technology and advancements and it can get confusing trying to keep it all straight. So, we’d like to untangle some of this confusion by asking the question: What is the difference between AGM and GEL technology?

Before we dive feet first into the differences between the two, let’s take a look at what exactly each of them is.

AGM Batteries

AGM technology stands for Absorbent Glass Mat. That explanation alone sounds ridiculous but wait. The absorbent glass mat refers to a fine fiberglass mat that is capable of absorbing sulfuric acid, making batteries spill proof. Makes more sense now right? In the 1980’s the demand was increasing for lighter weight and less hazardous batteries that could be used in aircraft and vehicles.

AGM technology allowed this demand to be met. All of a sudden batteries could be transported without hazardous material issues and the construction of the mat meant that batteries could now be shaped as a cylinder or the traditional rectangular cube.

GEL Batteries

GEL technology is another matter altogether. A gel cell battery is a battery that uses a sulfuric acid that has been mixed with fumed silica to create a gel-like substance that is immobile. Because of the GEL cell, the battery does not have to be kept upright and the electrons can flow between the plates without the threat of spilling.

These batteries produce few fumes which make them ideal to be used in places that don’t have much ventilation.

Know that we have a better understanding of them, let’s compare ’em.

The Differences

While these batteries are not the same, there are similarities that cause people to confuse the two. They are both non-spillable, are deep cycle (meaning they can be deeply discharged), and can be transported safely among other things. So what sets them apart?

– Preferable when a burst of amps is required.

– Can be easily recharged, in some cases up to 5 times faster.

– Can be produced at a lower cost than gel batteries.

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– Have a low internal resistance.

– Perform well in temperatures below 32 degrees.

– Does well in warmer environments.

– Does well with slow discharge rates.

– If recharged incorrectly the battery will failure before the end of its life cycle.

– Not suitable to be used as starter batteries because of an increased acid resistance.

– Do not perform well in below freezing temperatures.

So when trying to decide which battery to purchase consider a few things.

  • Whatapplication are you usingthe battery for?
  • Will the battery have to function in below freezing temperatures?
  • How will you recharge the battery?
  • Do you need a slow discharge rate or will you require bursts of power?

Once you have the answers to these questions you can determine the best battery for you. Warmer climate and lower discharge rates? Springing for the gel battery may just be the answer.

Colder climate and you want to use the battery as a starter battery? Definitely, go for the AGM. Understanding the battery you are purchasing will go a long way in preventing damage to your equipment and preserving the life of the battery.

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How Your Auto Battery Works

Here’s a simple guide to understanding how car batteries work, from the alternator to cold cranking amps to different types of car batteries. Find out:

How a Car Battery Starts a Car

The first purpose of an auto battery is to provide power for starting your vehicle. It also acts as a surge protector for the car’s computer and provides power for short-term use of things like lights, stereo, GPS or wipers when the engine is off.

The car battery is part of the starting system. There are three main components in this system:

  • The ignition switch is either the starter button you press or where you insert your key.
  • The switch controls the starter relay (also called a solenoid). When you turn the ignition, it sends a small electrical current to the starter relay. This causes a pair of contacts to close.
  • When those contacts close, the battery sends voltage to the starter motor, which turns some gears to start the car.

How the Battery Provides Power

The two types of auto batteries — flooded and AGM batteries — use lead-acid technology. A typical lead-acid car battery contains plates of lead alternating with plates made up of other materials, all immersed in an electrolyte solution of about one-third sulfuric acid and two-thirds water.

Turning the ignition triggers the acid in the liquid electrolyte solution to react with the active material on the plates (active material refers to any substance in the battery that reacts with the solution to discharge or recharge the battery). This generates a bigger electrical current. The current travels through the starting system in a chain of reactions that cues the engine to start.

What Are Cold Cranking Amps?

Cold cranking amps (CCA) refers to the amount of power a battery can supply for 30 seconds even at low temperatures. Larger engines require more power to start, as does starting the car for the first time on a cold day.

A high CCA rating is important for standard auto batteries in areas with subzero temperatures, since deeply discharged wet cell batteries can freeze solid in such weather.

How the Car Battery Recharges

The alternator is responsible for recharging your car battery as you drive. This part also supplies power for your car’s electronics when you’re underway. It is driven by the alternator belt from the engine. As the belt goes around, it generates electrical current to run your vehicle’s electronics. It also sends some current back to the battery to recharge it.

A voltage regulator controls this flow of electricity to keep it even and deliver the right amount of charge to meet needs like running the AC or heater. It also protects the battery from overcharging, which can damage it.

Why Does My Battery Die?

Over the life of a battery, discharge-recharge reactions happen thousands of times. Each cycle wears out the plates a bit, and over time the lead deteriorates. As your car battery loses capacity, cold cranking amps decrease.

Deep discharging, which happens when you use the battery to run the stereo, lights or other electrical systems in your car when the engine is off, is responsible for a good portion of battery failures. Discharging most of your battery’s capacity by using it in this manner for too long and then recharging it through driving can cause the sulfur in the electrolyte solution to stick to the lead and create other damage to the plates in the battery.

What Are the Different Types of Auto Battery?

The two most common auto batteries for sale today are standard wet cell batteries and absorbed glass mat (AGM) batteries. Both use lead-acid technology. The differences are in the needs of the car.

Standard Wet Cell Batteries

These are also called flooded, conventional or SLI (starting, lights, ignition) batteries. Some standard batteries have vents that allow for airing out corrosive gases, steam, and condensation (these may be called vented batteries). They have removable caps for adding fluid. Other wet cell batteries are closed systems, with no removable caps.

  • Service needs: Occasional simple maintenance including cleaning off corrosion on terminals and topping off the fluid with distilled water if the battery has removable caps. The battery should be visually checked every year. Battery charge should be checked before road trips and after summer before temperatures fall.

Absorbed Glass Mat (AGM) Batteries

These are a type of VRLA battery, which stands for valve-regulated lead-acid. They’re sometimes called regulated valve, dry cell, non-spillable or sealed batteries. They are called sealed because they have no removable caps, don’t vent gases and can’t leak any acid. They do have pressure-activated relief valves that open only if the battery overheats during recharging.

Some newer cars, such as those with start-stop technology, require AGM batteries. These batteries will continue to deliver power to a car’s computer and electronics even when the engine isn’t running.

AGM batteries hold a charge longer than standard wet cell batteries. They can tolerate periods of disuse and repeated deep discharging and recharging cycles better than flooded batteries. They have a short recharge period but they can be easily damaged by overcharging. They also perform well in harsh climates with extreme heat or cold.

  • Service needs: Charge should be checked before road trips and after summer before temperatures fall.

Wet cell batteries and AGM batteries are not interchangeable — your car requires one or the other.

Start-Stop AGM Battery Applications

AGM or Absorbent Glass Mat is an advanced lead-acid battery that provides superior power to support the higher electrical demands of today’s vehicles and start-stop applications.

AGM batteries are extremely resistant to vibration, are totally sealed, nonspillable and maintenance-free. AGM offers better cycling performance, minimal gassing and acid leakage when compared with conventional lead-acid batteries.

The end result of all of the features of AGM technology is superior life performance.

AGM Battery Applications

Start-Stop Vehicles, Large Audio Systems, Heated Seats and Other Electronic Accessories

If you’re looking to power a vehicle with numerous electronic features or plug-in accessories, you should consider a deep-cycle battery or a battery made with advanced technology like AGM.

AGM batteries are a great premium choice for high-end and advanced fuel-efficient vehicles with large power demands, and for people who seek greater reliability and longer life in auto batteries. Electronic features such as DVD players, GPS, heated seats and audio systems all add to the demands on a battery.

Start-Stop Vehicles

AGM batteries are also the preferred solution for start-stop vehicle technology, which rapidly gained popularity in Europe and entered the U.S. market in model-year 2013 vehicles.

Start-stop vehicle technology automatically shuts off the engine when your vehicle stops, such as at a traffic light or in stop-and-go traffic, and restarts it quickly and quietly when the clutch is engaged or the brake pedal is released. When the engine is off, the battery is the sole source of power to all the car’s electrical devices, such as air conditioning, the radio and the navigation system. And, in advanced start-stop systems with features like regenerative braking or passive boost, the battery is stressed even more.

In order to power electrical loads during engine-off periods and to support a high number of starts per trip, these vehicles need a battery that is more robust than the typical lead-acid battery. With superior cycling capability, charge acceptance and the ability to operate at a low state of charge, AGM is the technology of choice.

AGM Battery Construction

In AGM batteries, the positive and negative plates are separated by an absorbent glass mat that absorbs and holds the battery’s acid and prevents it from flowing freely inside the battery. The plates are tightly compressed into each cell and held under pressure in the plastic case. The internal compression limits the shedding of plate material caused by cycling and allows for significantly longer life. The element compression also lowers internal resistance and maximizes pulse power output. A rigid container maintains the necessary compression throughout the battery’s life.

The basic design also includes relief venting to release pressure from minor gassing that occurs during charging. The valves open at low pressure and close automatically to prevent air from leaking into the battery.

AGM Battery Benefits

If you have a vehicle which has the stop start feature then it is crucial you replace the battery with a specific AGM stop start car battery. These batteries are different than standard wet lead acid batteries which are fitted to vehicles without stop start functionality. Due to the greater demand on the battery caused by regular stop starting standard batteries will wear out very quickly as they are not designed to operate under those circumstances. AGM car batteries are and will last much longer than conventional wet lead acid batteries even if the lead acid battery is of premium quality and specification.

You can check if your vehicle has a Stop Start AGM battery fitted by looking in your owners manual or checking your existing battery. Your battery fitted should say AGM on the top or side specification label. Please contact us if you are unsure

Essential for Modern and Premium marque vehicles such as Mercedes, Land Rover, BMW, AUDI Porsche with high onboard power demands and stop start technology. AGM car batteries offer fantastic value for money and reliability; this is because they have low self discharge and more starting power than other car batteries with up to 50% more starting power. So when choosing an AGM car battery you can be assured of power, quality and reliability. It is essential you replace your existing AGM battery with the same type of AGM technology as your vehicle will have been designed to have one.

Instead of using normal lead acid constrcution they use a fibreglass type material that makes them spill proof, vibration resistant and holds the electrolyte in place. Our selection of AGM car batteries come mainly made by Bosch, offering you a wide choice of specifications and something for all budgets too.

AGM battery mainly uses its high performance combined with Auto Start-stop technology. However, even if the car does not have a start-stop system, the advantages of the AGM battery can be used: Auto Start-stop technology provides a greater power reserve, and traditional vehicles can also benefit from it, for example due to the longer battery life.

Advantages of Auto Start-stop technology

In addition to the advantages already mentioned, there are other reasons to upgrade to AGM batteries. It is recommended to replace the AGM battery in the following situations:

  • Large short trips of less than 10 kilometers or annual mileage of less than 10,000 kilometers do not allow the alternator to have enough time to fully charge the battery. Every time the battery is not charged to the full SOC (state of charge), the more difficult it is for the battery to start the vehicle next time.
  • If the vehicle is only used on a seasonal basis, the old traditional starter battery may discharge prematurely. This is especially true if there are unfavorable conditions in the storage location and the battery charger is not being used to keep it charged. AGM batteries can better withstand long downtime, because with Auto Start-stop technology, the electrolyte isolated in the diaphragm will not be stratified, thereby reducing sulfide. This means that AGM batteries are easier to charge than wet batteries after a long period of shutdown.
  • AGM batteries can also withstand extreme external temperatures and have high power reserves. The traditional starter battery’s response to extreme heat and cold causes a Rapid decrease in capacity and a faster discharge.
  • If the vehicle is equipped with a large number of non-standard electrical equipment, these equipment will increase the power consumption, for example: AGM battery is a complex audio system that can provide the necessary power for the vehicle that cannot be provided by traditional wet batteries.

AGM Batteries – The first choice for light commercial vehicles

In commercial use, vehicles are often used for multi-shift operations. AGM batteries can withstand higher loads during multi-shift operation better than ordinary starter batteries.

City trucks are usually also equipped with electric parts and special equipment. Due to the decomposition of active materials related to its capacity, conventional starter batteries quickly reach their limits and deteriorate. Due to the special design of the battery and the special mixture of active materials, AGM batteries can withstand more and deeper charging cycles than traditional batteries.

City trucks are usually also equipped with electric parts and special equipment. Due to the decomposition of active materials related to its capacity, conventional starter batteries quickly reach their limits and deteriorate. Due to the special design of the battery and the special mixture of active materials, AGM batteries can withstand more and deeper charging cycles than traditional batteries.

Automatic start-stop systems are more effective with an AGM battery

Vehicles that are equipped with a simple start-stop system and do not need to reclaim braking energy (recovery) are usually equipped with EFB batteries. However, even in this case, it is worthwhile to replace the AGM battery: Auto start-stop technology is reliable and trouble-free. Last but not least, the high load capacity of AGM batteries is impressive: During their entire service life, AGM batteries have better charge acceptance than EFB batteries.


AGM eliminates acid spilling in an accident because it is sealed. They can be installed at odd angles.

Have you noticed that more batteries are moving under the trunks and seats of some vehicles? If the battery is not under the hood, it is most likely an absorbent glass mat (AGM) or gel battery. Since AGM is sealed, it can avoid acid spills in accidents. They can be installed at strange angles.

These batteries are powerful due to their size and weight, which allows manufacturers to reduce the weight of the vehicle by several pounds. This is an important reason why they are increasingly appearing on new vehicles. In addition, these batteries have a larger backup capacity to support stop/start systems and flameout functions.

Here are the four AGM myths that you may have heard.

1)You can use your regular battery charger on AGM or gel cell batteries.

Due to the difference in internal resistance, these batteries like to charge slowly.

Many AGM battery chargers have a microprocessor that collects information from the battery and adjusts the current and voltage accordingly. Some have different settings to charge flooded batteries or AGM batteries. Overcharging will kill these batteries. In addition, the alternator is not a charger. Do not rely on the alternator to complete the work of the charger. If the battery is discharged to the point where the vehicle cannot be started, please use the charger as soon as possible to ensure that the battery is fully charged.

2)AGMS and gel cells can be tested the same way as conventional batteries.

These types of batteries have lower internal resistance than flooded batteries. Older capacitor battery testers/analyzers may not be able to accurately read these batteries. Most new battery analyzers have a special mode of AGM/gel battery. Old-fashioned load testers may not provide conclusive results.

Using a multimeter to measure the state of charge is different from using a traditional flooded battery. After removing the surface charge, the voltage of an AGM with a 100% state of charge may be 13.0 volts. A battery filled with water may only have 12.6 volts.

3)AGM or GEL cell battery replacement is the same as flooded battery replacement.

Although the battery installation of the two battery types may be the same, some vehicles require additional steps to tell the vehicle that the battery has been replaced.

Newer GM vehicles have a battery sensor module on the negative battery cable. Ford has a battery monitoring system (BMS). Other manufacturers have similar systems. If the battery is replaced, these systems need to be recalibrated using the scanning tool. If the system is not recalibrated, the alternator may overcharge the new battery and cause the replaced battery to quickly fail.

Some vehicles can self-learn the battery by measuring the internal resistance of the battery. But usually the scanning tool can enforce the program, so you know there will be no problems battery.

4)You can’t upgrade a customer to an AGM battery if the vehicle originally came with a flooded battery.

You can install AGM batteries into flooded battery applications. AGM batteries will provide vehicles with greater cold start power and greater heat resistance and vibration resistance. However, you never want to downgrade a vehicle equipped with AGM batteries to flooded batteries.

AGM battery can be said to be a kind of storage battery manufactured for start-stop system. Different from ordinary lead-calcium batteries, the adsorption type glass fiber board of AGM battery can ensure that the electrolyte is absorbed around the plates, so that the battery has more powerful charging and discharging capacity, faster charging and discharging speed and longer long-term deep cycle life. Effectively reduce the hidden danger of power loss and provide strong support for the start-stop system. Of course, the AGN battery without hydrogen system can also be used as an ordinary battery, but this will shorten the life of the AGM battery.

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