How Long Do AGM Batteries Last?

The Absorbed Glass Mat batteries also known as AGM batteries are the upgraded form of lead-acid acid batteries. These are known for their longevity and higher lifespan. Its structural differences and the assembly of the cells and other features make the AGM batteries last for a long time. 

But, for how long do AGM batteries last actually?

You can expect a 3-5 years longevity from the AGM batteries. A new AGM battery lasts up to 1.5-2 times longer than the lead-acid batteries. Because of it, the application and usability of AGM batteries are getting wider. 

But longevity varies with a lot of factors. Charging, sulfation, and proper use of the batteries can increase longevity and vice versa. With regular maintenance and equalization, the health of the AGM battery can be increased more. You can get up to 7-10 years of longevity from them.

How long do AGM batteries last?

AGM batteries have a better charge holding capacity. Besides, the discharge capacity of the batteries is lower. An AGM battery can last up to 4-6 years with normal uses. Besides, you can extend the lifespan of the battery with proper equalization and maintenance.

You may ask why this battery offers such high longevity. Well, there are a number of reasons for that, and here are a few reasons for you.

Lesser waste of efficiency

The efficiency of the battery depends upon structural formation and power production. In an AGM battery, the cells of the battery have a unique type of formation and assembly. Here the electrodes are not freely suspended like the lead-acid batteries. In a lead-acid battery, the electrodes cannot control the flow of the electron to produce current.

But in the AGM battery, the lead plates of the electrodes are kept close and in very confined plates. An AGM separator is used to absorb the electrolyte. This is sandwiched between the electrode plates. As a result, a more controlled electrochemical oxidation-reaction reaction can occur.

In a reverting way, the batteries can be charged more effectively as well. Therefore, the balanced charge receiving and delivery of the power makes the battery last longer. This way the efficiency of the battery can be retained.

High-grade Electrodes

The AGM batteries are constructed using very high-quality lead plates. Unlike the wet cell batteries, the electrodes in the AGM batteries are made of pure lead plates. No alloys are used in the electrodes.

These lead plates are very thin. Therefore, more lead plates can be accumulated together to ensure a higher number of lead plates. This ensures higher reactivity in the electrochemical reaction and less wastage. Moreover, the reactivity of the lead plates lasted longer which ultimately enhanced the lifespan of the AGM battery.

Controlled usage of the Electrolytes

In lead-acid batteries, liquid sulfuric acid is used as the electrolyte. After regular usage, the dilution of the sulfuric acid gets reduced. And furthermore, you have to fill the cell chambers with distilled water to maintain the dilution of the electrolyte.

But, the AGM battery is completely liquid-free. A fiberglass mat is used to keep the electrolyte completely absorbed within. The mechanism is like the sponge absorbing the liquids. This form of electrolyte reduces power wastage and ensures the controlled flow of electricity.

In the AGM cells, the electrochemical reaction takes place only when necessary. Besides, no maintenance is required to keep the cells flooded on a regular basis. Due to this, the battery experiences better longevity.

Sealed and Valve regulated Compartment

The compartment of the AGM battery has a dual ladder. Firstly, the cell chambers have a separate compartment. Along with that, the entire battery is kept sealed shut with a good grade of plastic. There is no way the battery cells can be affected by the atmosphere and its impurities. Therefore, the chemical reaction and energy conversion happens with higher effectiveness.

Besides, due to the valve-regulated compartment, only the internal Hydrogen gas is eliminated if the pressure grows. But, no outsider is allowed to get inside the cell chamber and interfere within the chemical reaction. That is why AGM batteries can last longer than other batteries.

Minimized Sulfation

Like the other lead-acid batteries, AGM batteries are not free from the sulfation process. The sulfation is a chemical reaction. Here the free Lead ions from the electrodes and Sulfate ions from the electrolyte react together to form a lead-sulfate precipitate. This lead-sulfate remains in the crystal form and accumulates on the negative electrode.

If the sulfation is not controlled and reversed back to ions, a permanent layer of lead-sulfate forms on the Cathode. As a result, the performance of the battery is reduced due to the reduction of the chemical reaction between the electrode and electrolyte.

The sulfation in the AGM batteries occurs in very negligible amounts. It is because the electrodes are not freely suspended in the liquid electrolyte continuously like the lead-acid batteries. Rather, the electrolyte remains in the absorbed form, and the reaction between the electrode and electrolyte happens in a balanced manner.

Can you determine the lifespan of an AGM battery?

An AGM battery is one of the latest and modern forms of Lead-acid battery. The lifespan of the battery depends on the usage type and maintenance of the battery. Here, we shall know about the methods of determining the lifespan of the AGM batteries.

Voltage Reading

The new AGM battery shows around 12.9-13V at 100% charge. It can last up to 6 years with normal usage. The average cycle life of the AGM battery is around 500. This voltage reading reduces with the time interval. You can check it using a  multimeter or voltmeter.

  • First, remove the battery and clean up the terminals from corrosion for minimal error deviation.
  • Keep the battery in a well-ventilated area with optimum temperature. High-temperature fluctuation gives wrong information.
  • Make sure your battery is fully charged. For checking the charge level, you can use a smart battery charger.
  • Connect a standard multimeter and voltmeter to the battery.
  • Check the reading of the voltage.
  • If the voltage fluctuates between 12-12.5V at full charged condition. It means the battery has around 80% health.
  • It can last upto 4 years more with equalization.

State of Charge

The state of charge of the battery shows how much charge the battery can retain after being fully charged. A good battery can hold up to 95-100%% charge after being fully charged. But, with the usage, the state of charge of the battery becomes lower. Because the charge holding capacity of the battery becomes degraded and the voltage drop is frequently seen.

  • Firstly, disconnect the battery from all of the electronic appliances.
  • Use steel wool to remove the corrosions from the battery terminals. 
  • You can use an automated smart battery charger with a digital display. It will directly show the current state of charge of the battery when fully charged.
  • You can check it manually also using the voltage reading. For this, connect a voltmeter and check the reading at a fully charged battery. 
  • Wait for a while and check the reading again. If the difference between the initial and final reading is high, the battery lifespan is lower.
  • But, if the initial and final voltage reading is closely connected then it has good longevity.

What factors affect the longevity of AGM batteries?

There are various factors that affect the longevity of the AGM battery. This battery is quite sensitive for use. The effects are stated below.

Overcharging

The AGM batteries are highly sensitive to overcharging. Since it does not possess an open and free form of the electrolytes the higher voltage has no place to sustain or become neutralized. That is why overcharging the battery damages the internal components of the battery. Therefore, the longevity of the battery becomes degraded with time.

Over-sulfation

Sulfation is a common phenomenon in lead-acid batteries. In this process, a layer of the lead-sulfate precipitate forms on the negative electrode. If not removed or reversed back, the layer becomes permanent. And thus the longevity of the battery is compromised greatly. It is because the electrochemical reaction is hindered between the electrode and electrolytes.

Depth of Discharge

The AGM batteries have a high limit of discharge. You can only discharge your battery up to 50% of the given state of charge. Going below that slowly damages the battery and enhances the sulfation. Overusing the battery can cause the battery to get discharged deeply. It is an irreversible process. The deeply discharging causes the battery health to downgrade.

Not recharging the battery

Recharging a battery is a common procedure for equalizing the battery. It maintains the electron flow speed in the battery and controls it. Besides, recharging the battery avoids sulfation and increases the reactivity rate. It helps the battery to be within the minimum limit of the battery being discharged.

Temperature and Environment

Though the AGM batteries are temperature-independent batteries. But, heavy fluctuation at the operating temperature results in interfering with the charging and discharging process. Therefore, the battery loses its longevity if it is used in very hot or very cold temperatures. The minimum optimum temperature should be maintained for a better lifespan of the battery.

Over-using the battery

Every AGM battery has a limit of amperage delivery. Even though the Cold-cranking amperage of the AGM batteries is higher. It should be kept to minimal usage. Rapid bursts of cranking amperage delivery may lead the battery to become dead sooner than expected. You cannot put excessive pressure on the battery as it can get discharged very easily in very little time.

Over corrosion

Corrosion in the terminals of the battery halts the flow of current from the battery to the electric appliances. The expected power delivery cannot be gotten due to the interference in the terminals. Therefore, it should be cleaned using steel wool for better longevity of the battery.

Does the AGM battery last longer than others?

These AGM batteries last longer than the other types of deep cycle batteries. There is much structural enhancement in the AGM batteries which improves both the performance and longevity of the battery.

The use of pure lead plates as the electrodes results in better electron flow to and from the electrolytes. Therefore, there is minimum waste in the current flow. Therefore, the plates can last longer than other electrodes of the other type of batteries.

Besides, in the AGM battery, the electrolyte is completely absorbed by the fiberglass mat of the AGM separator. It helps to keep the electrolyte more stable and increases the current production. Negligible contamination in the electrolyte occurs due to foreign materials. Moreover, a balanced flow of the current is observed which reduces the wastage of electricity.

In the AGM batteries, each cell works individually to produce 2.2V. The cell chambers contain a package of electrodes with an AGM separator containing the electrolyte and two grids protecting the cell. This unique formation increases the effectiveness of the battery. And therefore, the battery lasts longer than the other deep cycle battery types.

How do I know if my AGM battery is bad?

A bad AGM battery used for almost 5 years will show minimal power delivery. It is the basic observation to declare your battery being bad. Besides, you can also detect the battery as being bad or good by following a series of actions.

Step-1: Checking the Voltage

A fully charged AGM battery will show around 12.6V to 13V. But a bad AGM battery will show a huge difference from the standard value. For this, disconnect the battery from all sorts of electronic appliances. Recharge the battery to the fullest and take the reading of the voltage using a voltmeter. After waiting for some time, the reading should be taken again.

The difference between the initial and final reading will give the verdict of your battery being good or back. If the difference is low, then the battery is good. And if the difference is high the battery is considered to be bad.

Step-2: The state of charge

Using the previous process, check the voltage of the battery after recharging the battery. The initial voltage reading will show the current state of charge of the battery. When it shows 12.6-13.1V then the SOC of the battery is 100%. But, below the 12.5V the SOC is decreased. The following chart shows the relation between the voltage of the state of charge.

Voltage Reading(V)State of Charge (%)
12.8-13.3100
12.5-12.680
12.0-12.360(Sulfated)
11.9-12.040
11.7-11.920(Discharged)
Below 110(Discharged)

Step-3: heavy Load Testing

This step is the final test that shows the eligibility of the battery effectiveness. For this, you have to get a battery tester. It should be connected to the battery in an isolated and well-ventilated place. The battery terminals should be corrosion-free. Connect the tester terminal to the battery terminals firstly. Then connect the battery tester to the wall socket.

Select the correct testing profile specific to the AGM battery. Perform the load test three times for a good verdict. The battery tester in this test uses up the high bursts of amperage that will be sucked up from the battery for 30 seconds.

A good battery successfully completes the test maintaining the lower limit of the voltage. In good batteries, the voltage does not drop below 10.2V while performing the tests. But the battery shows voltage dropping below 10V at the time of the test.

Step-4: Physical Inspection

Physical damage degrades the performance of the battery. Since AGM batteries have a sealed compartment, slight damage or leaking in the plastic shall contaminate the battery. Therefore, the battery becomes bad. That is why the battery should be checked for leaking, deformation, and other physical damages. The corrosion in the terminal of the battery makes the battery bad.

Step-5: Not getting enough power

The AGM Battery being discharged or bad cannot supply enough power to the electronics. If your appliances cannot perform well due to a lack of power then the battery should be considered dead. Besides, the AGM batteries if they fail to ignite the engine and start it makes the battery bad.

You can also read How Safe Are AGM Batteries

Frequently Asked Questions About AGM Battery Longibility

Do AGM batteries last longer than lead-acid?

The AGM batteries last longer than the Lead-acid batteries. In the AGM batteries, all the important components such as the electrodes, electrolytes, and connecting terminals are made up of high-quality materials.

Besides, the unique assembly of the cells of the AGM battery makes it last longer than the Lead-acid battery. In the lead-acid battery heavy sulfation, leakage of the electrolyte, ineffective power delivery occurs. All these make the AGM battery have higher longevity than the lead-acid battery.

How long do AGM deep cycle batteries last?

The climate, operating temperature, and climate are factors for the deep cycle battery’s longevity. If maintained properly with charging and sulfation, a deep cycle battery can last for 4-5 years. Besides, the lasting of the battery can be extended with the optimum usage of the battery.

How long do AGM motorcycle batteries last

The sealed optima batteries used in the motorcycle can last up to 5 years. If heavy electronic appliances are used such as alarms, LED lights, and others the longevity may decrease. Otherwise, the AGM batteries with the spiral call can last up to 7-8 years as well. It depends upon the weather, temperature, and integrity. 

How long do Lifeline AGM batteries last?

The AGM batteries on average can last for 4-5 years. But you can extend the lifespan by following some common procedures. These can be like charging the battery using smart chargers. Using the correct float voltages enhances the longevity of the battery. Minimizing the voltage drop also helps with it.

With these, the AGM battery life can be stretched to 7-8 years maximum. Among all the batteries, the AGM deep cycle batteries have the highest longevity.

Here we added a tutorial video about the maintenance tips of an AGM battery.

Conclusion

AGM batteries are popular for their performance and longevity. The lifespan of the battery depends on some major facts such as usage and maintenance. Apart from that, the natural weather and operating temperature also alter the lifespan of the AGM battery.

Considering you are planning to switch to an AGM battery or buy a new one. You must have a clear understanding of how long do AGM batteries last. With it, you can have a rough idea about the batteries usage and maintenance. Besides, that you can start saving money for getting a new battery.

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Marcelo Araujo-Xavier

Hi, Marcelo Araujo-Xavier is here! I am the author of Batteryhint. I have been working in the battery industry for over 20 years and have a passion for helping people find the best battery for their needs. I have personally tested and reviewed hundreds of different batteries. I'm certified by the International Association of Automotive Battery Manufacturers. I have always been interested in batteries and how they work, so I decided to start this website to share my knowledge with others. I hope you find the information on this website helpful and informative. I will be regularly updating this website with new resources, If you have any questions or comments, please feel free to contact me. I would love to hear from you and help you find the best battery for your needs.

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