The battery landscape is incomplete without an AGM battery. Absorbed glass mat batteries or absorbent glass mat (AGM) batteries have gained widespread popularity in recent years. AGM batteries are also known as “dry,” “membrane,” or “starved electrolyte” batteries.
While a conventional battery could compete in terms of adaptability and efficiency, AGM batteries have gone a step further in redefining battery design and resilience.
Where traditional batteries struggled to meet the high power demands of modern vehicles or run electronic systems for a longer time, AGM batteries filled the gap as a maintenance-free, powerful alternative for a diverse range of applications.
From powering motorcycles and submarines to everyday cars and trucks, AGM batteries are making their presence felt like never before.
Keep reading to learn more about an AGM battery and how it is different from other batteries.
What is an AGM Battery? AGM Technology Explained
AGM batteries are based on the standard SLA (sealed lead-acid) battery construction. The difference lies in the addition of an ultra-thin glass mat (or AGM separator) that “absorbs” the electrolyte and makes the battery non-spillable. A sealed lead-acid battery is also known as a VRLA battery.
Although sealed AGM battery technology originated in the early 1980s, it evolved further for its early uses in military aircraft applications that focused heavily on power, reliability, safety, and weight.
As the first company to develop the AGM technology for commercial non-military use, Concorde is known for its AGM batteries referred to as VRSLAB (Valve Regulated Sealed Lead-Acid Battery) or VRLA (Valve Regulated Lead Acid).
The unique design of AGM batteries provides them with a higher voltage input ideal for boats, cars, golf carts, power sport vehicles, RVs, and trucks, among others.
For example, an AGM car battery offers many benefits, such as good electrical reliability and cycle life, high specific power, low self-discharge, and excellent vibration resistance.
How do AGM Batteries Work?
An AGM battery contains potive and negative lead and lead oxide plates that release electrons when they come in contact with the electrolyte (a mixture of sulfuric acid and water).
While the plates are saturated with battery acid, an ultra-fine fiberglass mat is sandwiched between the plates, compressed, and then welded in place.
Tiny glass fibers absorb the electrolyte mixture and maintain uniformly distributed contact with the active lead materials. In addition, the electrons in an AGM battery flow in a series circuit through six cells for a total of 12 volts.
AGM Battery vs. Other Batteries
Although AGM, gel, and flooded batteries are classified as lead-acid batteries, AGM batteries stand out in the internal construction of the battery. AGM batteries are easy to install, with zero maintenance and gas formation.
Zero-to-low maintenance and spill-proof design make an AGM battery extremely suitable as a solar battery.
The construction of an AGM battery is suitable for systems that require high currents (such as starting an engine). Furthermore, AGM battery poles can be unscrewed for the battery to be combined with any other standard battery terminal.
A battery type differs in price and lifespan. For example, an AGM battery is believed to last around 600 cycles, but a lithium battery may last 7,000 cycles. In addition, AGM batteries are expensive than flooded batteries and cheaper than gel batteries.
AGM battery vs. Gel battery
Both AGM and gel batteries are categorized as VRLA batteries that are known for easy maintenance. Unlike an AGM battery, a gel cell battery uses a special type of silica gel to hold the electrolytes together and facilitate the free movement of electrons from the plates.
Gel batteries lose power faster at lower temperatures, but AGM batteries work well even in extreme weather conditions (suitable for power-hungry vehicles such as snowmobiles).
Moreover, a deep cycle gel battery has other disadvantages, such as a shorter lifespan and slower charging time than a deep cycle AGM battery.
AGM battery vs. Lead-acid battery
How is an AGM battery different from a typical lead-acid battery? Unlike conventional lead-acid batteries, AGM batteries provide better cycling performance and faster charging performance.
AGM batteries demonstrate minimal gassing and acid leakage, last longer and are resistant to freezing. Furthermore, the spill-proof and leak-proof design makes it easier to mount an AGM battery in any direction.
AGM battery vs. Lithium battery
There are several types of lithium batteries or lithium-ion batteries based on battery chemistry, such as Lithium Iron Phosphate (LFP), Lithium Cobalt Oxide (LCO), and Lithium Nickel Manganese Cobalt Oxide (NMC). Lithium batteries weigh about one-third and last approximately 10 times longer than AGM batteries.
The longevity of an AGM battery depends on the quality, maintenance, and depth of discharge. Lithium batteries are costlier than AGM batteries due to their efficiency, higher energy density, longer lifespan, and ability for deep discharge without damage.
AGM battery vs. Flooded battery
A standard flooded battery or a wet cell battery consists of a number of lead plates divided by a series of separators—the plates and separators along with a liquid electrolyte (sulfuric acid) are all packed inside a solid casing.
However, in an AGM battery, a glass mat separator enables the battery to have around 2x longer lifespan than a traditional flooded battery.
In contrast to flooded lead-acid batteries, AGM batteries work well even when stored at very high or low temperatures because AGM batteries do not contain a free liquid that could freeze or evaporate in extreme climates.
Generally, sealed AGM batteries absorb the liquid electrolyte and store it in a dry state rather than in a free liquid form.
EFBs (Enhanced Flooded Batteries) have been introduced as a lower tier option to AGM batteries with respect to durability and performance.
However, the one-of-a-kind design features (glass mat separator, higher pack pressure, and recombinant lid technology) of the AGM battery makes it better suited than an EFB battery to meet the rigorous demands of higher specification vehicles.
Although AGM batteries do not need any maintenance on a regular basis, they still require “venting” or battery ventilation to avoid build-up of toxic gases. Battery boxes can be used to protect a variety of batteries, including AGM batteries from the outside elements, such as water and UV exposure and potentially explosive gas build-ups.
Advantages of AGM Batteries
The main advantages of AGM batteries include:
Greater mounting flexibility
As the glass microfibers in an AGM battery absorb acid without leaving any room for free acid leakage, an AGM battery provides greater mounting flexibility.
Higher voltage output
An AGM battery can deliver higher energy output even in the most challenging conditions.
Longer lifespan
The battery design (thicker plates) of an AGM battery results in minimal active material shedding and increases battery lifespan.
Start-stop systems
AGM batteries have an impressive starter function and are preferred for greater reliability and longer auto battery life, especially in start-stop applications with the highest energy demand.
Furthermore, AGM is the technology of choice for start-stop vehicles because AGM batteries have superior charge acceptance and cycling life apart from the ability to operate at a low state of charge.
Spill-proof design
There is no leakage or spillage risk as these batteries are totally sealed for use.
Vibration resistance
AGM batteries are highly resistant to vibration because the woven fiberglass mats and plates are packed tight—thereby making the batteries immune to vibration. In addition, AGM batteries’ glass fiber technology ensures low internal resistance.
Other potential advantages
AGM batteries are claimed to have higher starting power with better discharging and recharging efficiency. These maintenance-free batteries are also perceived to be resistant to corrosion and degradation with slower discharge rates.
While entry-level AGM batteries have limited reserve capacity, higher-end models in the market have better capacity ratings.
Disadvantages of AGM Batteries
The primary disadvantages of AGM batteries include:
Higher manufacturing cost
Higher production and manufacturing costs make AGM batteries relatively expensive for use when compared to other battery types.
Sensitivity (overcharging and undercharging)
Overcharging and undercharging affect the life and performance of AGM batteries due to their low tolerance to such conditions.
A solar panel can also charge an AGM battery through a solar charge controller that regulates the current and battery voltage (from the solar panel) to avoid battery damage.
Low specific energy and reduced charging capacity
AGM batteries have low specific energy and display lower charging capacity over time—these limitations make them unsuitable for some devices.
AGM-compatible charger
Unlike traditional battery chargers, smart chargers are required for AGM batteries that rely on AGM-specific battery chargers to monitor amps, volts, and ambient temperatures.
Uses of AGM Batteries
As widely used SLA batteries, AGM batteries are a sought-after choice for fuel-efficient, high-end vehicles with large power demands. It is not, therefore, surprising to see AGM as the preferred motorcycle battery for upscale motorcycles.
Moreover, the higher CCA (cold cranking amp) rating of AGM batteries is responsible for their reliable performance in cold temperatures and enhances usability for marine (marine battery), motor home, and robotic applications.
Battery manufacturers worldwide continue to tap into the AGM technology potential to manufacture high-performance AGM batteries.
For example, Yuasa AGM batteries are recognized globally in the power sports battery market. In 1983, Yuasa launched the first motorcycle maintenance-free AGM batteries with the YT series.
The Crown Battery line includes a broad range of industrial deep cycle batteries and SLI (starting, lighting, and ignition) batteries for varied applications, such as automobiles and light trucks, electric forklifts, pallet trucks, farm equipment, floor care equipment, marine and recreational vehicles, etc.
Conclusion
Despite the higher initial investment, AGM batteries provide a wide range of benefits, including longer battery life, faster recharging, and adaptability to demanding conditions. The non-spillable and maintenance-free AGM batteries handle high electrical loads and are ideal for start-stop applications.
AGM batteries are designed to meet OEM (original equipment manufacturer) vehicle demands. The growing need for battery power is accelerating AGM use in today’s vehicles. Moreover, AGM batteries are easy to recycle, which makes them environmentally friendly.
The traditional battery has evolved in various ways. When it comes to AGM batteries, the potential and possibilities are far too many to ignore.
