AGM batteries otherwise known as Absorbed Glass Mat batteries are one of the technologically advanced batteries in this era. The primary use of AGM batteries lies in vehicles and recreational vehicles(RV). Gel batteries and lithium-ion batteries are also used widely in vehicles.
There can be many reasons to replace the existing battery we have under the hood. That is why it is important to understand how do I know if my battery is AGM. Knowing the battery is AGM or not will provide assurance about the next step to be done with the battery. It may be either repairing the battery or replacing the battery with a new one.
How to Be Sure That My Battery is An AGM Battery
Identifying your battery can be tricky for beginners. But following simple procedures will help you understand the build and type of battery you possess.
Visual Inspection
The AGM batteries have a unique build-up. The compartment where the cells reside is completely sealed. But some AGM batteries have a safety valve located on the side of the lid. It is for releasing the internal pressure caused by the accumulation of the gas. Otherwise, all AGM batteries have a flat surface lid with no openings except for the positive and negative terminals.
On the other hand, standard flooded batteries have six-cell openings on the lid which remain closed by protective caps. Gel batteries are quite similar to the AGM batteries from the outside but are valve-operated. Therefore, all gel batteries have a valve located on either side or top of the battery.
Labels and markings on the battery
All batteries have a clear indication of the type of battery on the labeling. You can find the battery labeling on top of the lid, or posted in the frontal region. The battery type will be written clearly there. If the battery is lead-acid, it will say wet cell battery, flooded acid battery, etc on the label.
For the AGM batteries, you can see some initials saying dry cell battery, Sealed Regulated Valve(SRV), or Non-spill battery, etc. gel batteries have clearly written “Gel-Filed” on the labeling of the battery.
Physical Inspection
If for some reason considering that the labels are damaged or worn off, then other techniques need to be followed.
You can check for the electrolyte type of the battery you have. For this follow the series of actions.
- Firstly, unscrew the connectors with the frame inside the hood.
- Switch off all the appliances and shut down your car engine.
- Pull the connecting terminals and move away from the cables very carefully.
- Pull off the battery and keep it on a flat surface.
- Shake the battery gently to and fro.
- Listen to the movements of the electrolytes inside the battery.
- If the battery has liquid electrolyte then you can hear it splashing on the cell chambers.
- In-gel batteries no noise will come as the electrolyte lies in gel formation
- For the AGM batteries, you can slightly hear the movements of the packed cells in the chambers but the splashing sound of an electrolyte can be heard.
What does an AGM battery look like?
There are mainly two types of AGM batteries available currently in the marketplace. These have very distinguishable structures.
The first type of AGM battery may look like a normal wet cell battery. But a closer look you will see at the lid of the battery is completely flat. Besides, the edges and corners of the battery casing are completely sealed off. In the whole of the battery, there are only two connecting terminals available on the top. There remains no way to open the battery or the cells with water.
There is a new form of AGM battery that has a cylindrical form of cells. These AGM batteries are very easily distinguishable. You will find six cylindrical cells with 3 rows and 2 column formation. All the cells are connected together in a series connection. And being combined there remains the lid of the battery on top. The Optima batteries are made with this type of structural formation.
The differences between Gel, AGM, and Standard Battery
In the marketplace, there are mainly three types of batteries available commonly. These are the Gel-filled battery, Absorbed Glass Mat battery(AGM), and standard lead-acid batteries. The comparison chart of the batteries is stated below.
| AGM battery | Gel Filled Battery | Standard lead-Acid Battery |
| Electrolytes get absorbed by the Glass mat | Electrolytes are mixed with Silica to form Gel-based electrolyte | The liquid form of the electrolyte is used |
| Pure lead plates are used as electrodes | Mostly pure lead plates are used | Lead alloys are used as an electrolyte |
| Completely sealed and spill-proof | Spill-proof due to sealed battery casing | Not spill proof; Lid has cell openings |
| Vibration resistive | Vibration resistant | No vibration or leakage resistive |
| Quick charging facility | Charging time is good | Takes a lot of time to get fully charged |
| Depth of discharge is 50% | Depth of discharge lies within 50% to 80% | Depth of discharge is 80% |
Benefits of Knowing if Your Battery is AGM
If you find out that the battery you possess is an Absorbed Glass Mat or AGM battery. Then it can be a relief for you. Because AGM batteries have lots of benefits. Moreover, the AGM battery is highly cost-effective than the other batteries.
Advanced Structural Technology
The AGM battery is the upgraded form of conventional wet cell batteries. It works on the similar principle of electrochemical reactivity. But the formation of the cell is very different from the standard flooded batteries.
Electrodes in the AGM batteries are very thin and pure Lead plates. There are two electrodes of positive electrode known as the cathode and the negative electrode as the anode. In between the electrodes, there remains a layer of AGM separator. This consists of the fiberglass mat. It can absorb the electrolytes such as the sponge absorbing the water.
Moreover, two grids are found on the outer layer of the cells. All these layers are closely packed by compressing. Since the AGM separator absorbs the electrolytes there remains no free liquid form of electrolytes in the cell chamber. This reduces the weight of the battery and enhances the overall effectiveness.
Lower Self-Discharge
The AGM batteries have a very slow self-discharge ability. It discharges overtime at a very slow rate. Therefore, even if you leave your vehicle untouched for a while, it will actively start up. The cranking power remains intact. IT is available to deliver the emergency power supply to the ignition system of the vehicle. Unlock the wet cell batteries.
High-Power Output Capacity
The cell engineering of the AGM batteries prevents the loss of energy uselessly. There are no free liquid electrolytes inside the AGM battery. All the electrolytes are absorbed by the AGM separator and remain very close to the cathodes and anodes. So, the output from the electrochemical reaction is higher than other batteries of a similar principle.
It makes sure the voltage output remains consistent even with a high output of cranking power at the time of need. The amp release remains consistent most of the time and voltage from every cell remains equivalent to each other as well.
Temperature independent
One of the major drawbacks of electrochemical batteries is temperature dependency. The conventional wet cell batteries are used to halt the voltage output due to the interruption in the free electron movement throughout the electrolytes. This can be an important factor for answering how do I know if my battery is AGM.
But in the AGM battery, the electrolyte remains closely packed with the electrodes in an absorbed form. Therefore, the temperature fluctuation has minimal impact on the electron flow from and to the electrodes. As a result, no interruption in power delivery is seen from the AGM batteries. It lightens up the vehicle engine even in very cold temperatures.
Spill-Proof Battery
The AGM batteries have no liquid electrolyte inside the cell chambers. Because the glass mat in the AGM separator completely absorbs the liquid electrolyte. Moreover, the compartment or the battery casing of the AGM battery is engineered to be sealed shut. There is no opening in the entire battery covering.
Many AGM batteries have safety valves but all those are made to be one way. Therefore, there is no way that the AGM battery can cause any sort of leakage. Handling and movement of AGM batteries are thus way much safer and friendly than those conventional batteries.
Anti-Vibration Batteries
One of the serious disadvantages of Lead-Acid batteries is the battery is not vibration resistive. If your vehicle goes off-road for some reason, then the effectiveness of the battery goes down.
The AGM batteries are made in such a way that the battery keeps up with the constant power supply even at high vibrations. The spiral AGM batteries known as Optima batteries act better in high vibration conditions. That is why, in dirtbikes, ATVs, and rally cars the usage of Optima batteries is increasing.
Quick Charging Facility
AGM batteries are engineered to be charged very quickly. You can use the smart chargers to easily charge the AGM batteries when required to the fullest. It takes 5 times less amount of time to get the full state of charge. An averagely used AGM battery takes 5-6 hours of constant charging.
On the other hand, conventional Wet cell batteries take almost 8-10 hours to become fully charged. Therefore, comparing the batteries it is seen that the AGM batteries can serve better in productivity.
Very Low Sulfation Rate
Most of the Lead electrode-based batteries have a high sulfation rate. It means the accumulation of a precipitate of lead-sulfate on the electrode and decreasing the electron flow in between the electrodes. Sulfation is one of the reasons batteries tend to lose power before the warranty period ends. It happens mostly in the flood acid batteries.
But, in AGM batteries, no free liquid electrolyte is found. As a result, the sulfate ions have no medium to react with the lead ions to form the Lead-sulfate precipitate. Even though sulfation takes place, it happens very negligibly.
High Cold-cranking Amperage
Old lead-acid batteries have a very low capacity to produce high CCA. But the modern AGM batteries have the tendency to produce CCA more than 1000 easily. This is an important feature for cold countries.
Because in freezing temperatures, the batteries fail to produce enough electric current to ignite the engine. But AGM batteries have the ability to do so in minimal temperatures. Besides, there are lots of variations of batteries with a wide range of CCA ratings.
Frequently Asked Questions for AGM Battery
The most commonly asked question asked by the consumers of the AGM batteries is discussed in this section.
Are car batteries standard or AGM?
It depends upon the vehicular models. Most of the 90s cars still use the standard lead-acid batteries. But, modern manufacturers use AGM batteries as the primary car battery. Besides, extreme vehicles such as dirtbikes, ATVs, and rally cars used spiral AGM batteries for better performance.
How to tell if a BMW battery is AGM?
You can perform a visual and physical inspection to confirm that the BMW battery is an AGM battery. If your battery does not have any caps on the lid and shaking the battery doesn’t cause any splashing sound then it is an AGM battery.
Is my motorcycle battery AGM or Lithium?
Motorcycles use both types of Lithium-ion and AGM batteries. You can identify the battery using the weight test. AGM batteries are way too much heavier than the Li-ion battery. There will be specific labeling on the lid of the battery to guide determining the type of the battery.
Conclusion
In order to replace, and repair your battery it is mandatory for you to know the battery type. There are several types of automobile batteries available in the market. These are the AGM battery, flooded battery, and gel-based battery. So the question arises: how do I know if my battery is AGM?
You can easily identify the battery you have by doing a visual inspection. For confirmation, you can also do the physical inspection test. Doing these are important because you cannot buy the required battery for your vehicle without knowing the battery it already had. Besides, upgrading the battery also requires the identifying process of the AGM battery.
