Can You Desulfate An AGM Battery?

Sulfation is one of the major problems caused by the negative chemical reaction in deep-cycle batteries. It happens mostly in the conventional lead-acid battery. The negative electrode which is otherwise known as the cathode causes the sulfation.

The Absorbed Glass Mat batteries have been engineered with new and advanced technologies. Its electrodes have been made with pure lead plates. Besides, the plates are very thin and placed in a confined and compact manner. That is why compared to other batteries, the rate of sulfation is lower in the AGM batteries. 

Here, the question is whether can you desulfate an AGM battery or not. The positive thing about AGM batteries is that you can easily desulfate the AGM batteries. Following the series of orders will help you to remove the sulfation.

What exactly does desulfation mean for AGM batteries?

Before knowing about the desulfation, we shall get enlightened about the sulfation method. The deep cycle battery works on the principle of an oxidation-reduction reaction. It is an electrochemical process through which the deep cycle battery produces energy.

In deep cycle batteries like AGM batteries, Lead-acid batteries, and Gel batteries two electrodes and electrolyte is used as the major component. The electrolyte used in the battery is mainly dilute Sulphuric-acid. It breaks into the sulfate and Hydrogen ions in the solution.

Now the positive and negative electrodes are made up of Lead plates. In the negative electrodes, a layer of Lead-sulfate crystal accumulates due to voltage fluctuation and chemical reaction. This inhibits the effectiveness of the electrodes and so the power production becomes minimized.

The good news is that Sulfation is a temporary and reversible process. The formed lead-Sulfate crystal can be broken down into ionic forms. As a result, in the solution, the quantity of free ions and charge increases the current flow increases.

Desulfation is the process to use the reversibility of the crystal formation and maintain the balance of the ions in the electrolyte. The AGM batteries can be desulfated using a compatible battery charger or desulfator. These are smart devices that automatically detect the sulfation rate in the battery and remove it by choosing the best suitable desulfation profile for the battery.

The desulfation should be performed very quickly. It is because the lead-sulfate crystals can form a hard and permanent layer on the electrode. This will actively reduce the battery life and charge holding capacity of the battery. Your battery will fail to deliver a sufficient amount of cranking amps when required.

That is why you have to desulfate an AGM battery from time to time. This will keep the state of charge optimum and won’t degrade the battery’s health.

Is it necessary to Desulfate an AGM battery?

The sulfation of a battery is a common phenomenon. Like most other Lead-acid batteries, the AGM batteries are supposed to get sulfation sometime in their lifetime. It is important to keep your AGM battery desulfated.

Desulfation Keeps Your Battery Health Optimum

Sulfation in the AGM battery slowly degrades the battery’s health. It results in the battery being discharged more often than normal. Now, the depth of discharge of the AGM battery is only 50%. Your battery being highly discharged will definitely affect the overall battery performance and the longevity of the battery.

That is why the AGM battery is sensitive to over-sulfation. It will reduce the battery’s health and slowly the battery will die. All these can be prevented by desulfating the AGM battery on time. Besides by regular desulfation you can extend your AGM battery life more than the expected time. A well-maintained battery can serve for 4-5 years.

Improves the Power Delivery

Desulfation in your AGM battery prevents the flow of current. Since the lead-sulfate crystals get deposited on the Lead cathode. It inhibits the electrode to react further with the electrolyte. Hence, the flow of free electrons through the electrode is inhibited. This ultimately degrades the power delivery.

Highly sulfated batteries cannot produce sufficient cranking amps. Therefore, you cannot get your electronic appliances or the car working properly. For this, you have to perform the reconditioning procedure of the battery which shall help the battery to get back to its original state.

Desulfation can be tough if the crystals are hardened on the plates. The more time you allow the sulfation process to impact the more your battery becomes dull. Desulfation will separate the solidified crystals of the lead-sulfate. And it will turn those into positive and negative ions which shall return back to the electrolyte.

This way, the electrodes get their full capability of flowing the electrons between them. Along with that, in the electrolyte, the amount of the charges rises. Therefore, the overall power delivery from the battery increases. AGM batteries are made for producing high cold-cranking amps. These cannot be left being sulfated for a long time.

Desulfation Enhances The Charge Holding Capacity

Sulfation significantly reduces the charge holding capacity of the AGM battery. No matter how much you recharge your battery it cannot hold the state of charge for a long time. It can be confirmed using the voltmeter. The sulfation makes the battery drop in voltage very quickly.

To counter that, regular desulfation of the battery is mandatory. Removing all the unusable crystals back into the electrolyte lets the battery hold more charge. The accumulated lead-sulfate crystals avoid the electrolyte to hold the charges as there remain few free ions.

This way, you can increase your battery’s state of charge to a stable condition by desulfating the battery on a regular basis.

Increases the Longevity of the AGM battery

Heavy sulfation will lead the battery to get deeply discharged if left untreated for a long time. Now, the battery getting discharged frequently affects longevity. On average, an AGM battery has a limit of life expectancy of 3-4 years.

But if you desulfate your battery on a regular basis, you can improve the longevity of the battery. A routine desulfation procedure will keep and maintain the balance of the charges in the electrolyte. Besides, it will increase the reactivity of the lead plates eventually. This way you can easily stretch your battery life to more than 6 years.

Is it possible for you to Desulfate an AGM battery?

Absorbed Glass Mat battery is an advanced form of conventional lead-acid battery. The main difference between an AGM battery and a Lead-acid battery lies within the construction of the AGM battery cells types. 

AGM batteries Are Lead-acid battery

Sulfation occurs more often in lead-acid batteries than in AGM batteries. It is because standard batteries have liquid electrolytes and thick electrode plates directly suspended in the electrolyte.

On the other hand, in the AGM batteries, the cells are made up of confined and compressed f cells. In each cell, the AGM separator being absorbed with sulfuric acid remains sandwiched between the plates. Therefore, no free liquid form of electrolyte is found in the AGM battery. For this, comparatively, few sulfation cases happen in the AGM batteries.

You can easily desulfate a sulfated AGM battery. This can be done in many many ways. The best way to desulfate an AGM battery is to get a suitable smart desulfator device. Or automated battery chargers can also be used to desulfate the battery.

AGM batteries Have a Lower Sulfation Rate

Unlike the flooded wet-cell batteries, the AGM batteries have a lower rate of sulfation. AGM batteries are quite sensitive to overcharging. But still, these can be desulfated using the basic methods such as other battery varieties.

You can desulfate an AGM battery using multiple ways

An AGM battery is more advanced than conventional batteries. Most of the automated chargers in the market have an option separately for desulfation of the battery. 

Moreover, you will also get dedicated desulfating devices from the market which specializes in AGM batteries. All these give enormous options to the AGM batteries for getting desulfated.

Desulfation is an Easy Process

Desulfation of AGM batteries is an easy process. It doesn’t require any need of an expert or professional. You can do it by yourself in your garage. All you would need is the specified smart charger for your AGM battery. 

Besides, it takes less time to desulfate an AGM battery. It is because compared to the lead-acid battery sulfation occurs very slowly in the AGM batteries.

When do you understand you need to desulfate an AGM battery?

Sulfation is one of the processes that inhibits the overall performance of your AGM battery. That is why, when heavy sulfation takes place you will know when to desulfate it.

When your AGM battery fails to provide the expected cranking amps to your vehicular engine. Then it can be the fault of sulfation. Because sulfation prevents producing heavy amp-hours(Ah) which is required to ignite the engine. Here you will have to desulfate an AGM battery.

After getting deeply discharged, when your battery fails to hold the charger consistently. Then it can be anticipated that it requires desulfation. Deeply discharging the battery energizes the sulfation process because the specific gravity of the electrolyte falls below 1.227. 

Often, the battery also cannot hold the voltage even after being completely charged. Sometimes it happens due to the reduced battery life. But if the battery has not crossed the warranty limit, then sulfation must be the culprit. At that point, you would want to consider desulfating your AGM battery.

You can use the voltmeter to check the consistency of the state of charge of the AGM battery. If the battery cannot retain the charger status for a long time without being connected. Then you should understand that your AGM battery requires desulfation.

Apart from that, the desulfator and the battery charger can show you the sulfation status of the battery.

How can you desulfate an AGM battery?

There are several ways to desulfate your battery. In this section, only the most favorable methods for the AGM batteries will be discussed.

Desulfation Mode

Most of the modern day fully automated battery maintenance devices have the desulfation mode. This device detects the sulfation activity in your battery and recommends desulfation. You can use this device for desulfating the AGM battery.

The battery maintainer devices are relatively cheap and are easy to use. These have digital displays to show all the battery parameters and status. Based upon the diagnosis you can select the time requirement and other parameters for the desulfation process.

  • First, disconnect all the cables and appliances from your AGM battery. 
  • If it is installed in your car, then unscrew the safety frame. 
  • Then take out the battery and keep it in a shady area.
  • Make sure the area is very well ventilated. 
  • Connect the battery maintainer to the wall socket of 120V.
  • Clean the battery terminals using steel wool. It will remove the corrosion.
  • After that, connect the cables from the device to the battery carefully. 
  • Select the correct desulfation mode and time and switch on the device.
  • Keep a voltmeter connected to the battery for preventing an overvoltage attack.
  • Allow the process to be complete in between 2-3 hours.

Recharging the AGM battery slowly

This process was used back before the invention of the desulfation method. By pushing consistent voltage and low amperage the sulfation products break down. For this process, you have to get a good quality automated AGM battery charger. It is better to wear silicon gloves and goggles for safety measures.

  • First of all, remove the connectivities and keep the battery isolated.
  • The charging area should have good airflow.
  • The battery charger should be connected to the wall socket.
  • Turn on the charger and connect the cables with the battery terminals carefully.
  • Select the charging profile for the AGM specific.
  • Keep the voltage input to 20V and amperage input to 2-5amps.
  • Attach a spare voltmeter to track the real-time voltage of the battery. Because AGM batteries are sensitive to overcharging.
  • Start the charging process. It may take 5-6hour to complete full charging of the battery. You must check the state of charge of the battery from time to time.

Trickle Charging

Normally, trickle charging a battery means very slow charging under minimal voltage. This is an effective way to desulfate an AGM battery. Highly sulfated batteries may require trickle charging for getting the battery rid of sulfation.

  • Firstly, all the electronic appliances should be disconnected from the battery.
  • You can store the battery in a shady and windy space.
  • Clean up the terminals from corrosion.
  • Connect your regular AGM charger with the battery and connect the charger to the wall socket of 120V.
  • Select the trickle charging option from your smart charger. Lower the voltage input if it is possible. 
  • Then start the charging process. 
  • Connect a multimeter for supervising the voltage of the battery.
  • It may take from 24-48 hours for the desulfation procedure to complete using this method.

How much time does it need to desulfate an AGM battery?

The time required to desulfate an AGM battery depends upon the amount of sulfation your battery possesses. Besides, it also depends upon the state of the charge of the battery. Deeply discharged batteries take a lot of time to get desulfated.

Normally, a slightly sulfated AGM battery may require 2-3 hours for desulfation. It can be achieved using the dedicated desulfation modes available in the battery maintainers. 

On the other hand, highly sulfated batteries may take up to 24-36 hours or more to completely desulfating the battery. A deeply discharged battery may even take 48 hours of desulfation.

Here we attached a tutorial video about – how to recondition an AGM battery. Follow the video for more detail:

Frequently Asked Questions

In this section, we shall look into the most commonly asked questions from the consumers regarding the desulfation of an AGM battery.

How do you rejuvenate an AGM battery?

An AGM battery can be revived using the jump-starting process. For this, you will require a good AGM battery connected to the dead battery in parallel. The high amperage of the fast charging profile is exerted on the good battery. This shall jumpstart the dead battery and increase its voltage slowly. After several hours, by regular charging, the dead battery can be revived.

How do you clean an AGM battery?

An AGM battery is a maintenance-free and completely sealed battery. You can keep the terminals of the battery cleaned of the corrosion by regular scrubbing using the steel wool. Besides, there are some valves for maintaining the internal pressure. These valves should be cleaned using soft buds and soft clothes.

Will a trickle charger Desulfate a battery?

Trickle charging is an effective way to desulfate a battery. It works better on deeply discharged batteries. But, trickle charging a battery can take up to 48 hours of time for complete the process.

Will a sulfated battery hold a charge?

A sulfated battery cannot hold charge like the original state. The sulfated battery cannot be returned to the original state by 100%. So the holding capacity of the sulfated battery is very minimal compared to the desulfated battery.

How do you know if a battery is sulfated?

A sulfated battery cannot charge for a long time. It shows reduced voltage output in the voltmeter or multimeter. Beiseds, the power output is not sufficient. The Amp-hour, cranking  amp and the reserve capacity of the battery gets reduced if the battery is sulfated.

Using these signs, you can detect the sulfated battery. Moreover, the sulfate detection option in the smart battery maintainer shows you the status of the battery sulfation.

How do you fix a sulfated battery?

Fixing a sulfation battery can be done by using a battery maintainer. These devices have a dedicated desulfation method. Besides, the battery chargers are cheap. These can be used to remove the sulfation in the battery.

You can also check How long do AGM Battery last


Sulfation in the lead acid batteries degrades the battery performance. With lack of inspection, the battery loses its longevity due to the need of desulfation. Storing the battery in a discharged way contributes to the sulfation process. That is why you have to keep a keen eye on the performance of your AGM battery. 

Since an AGM battery is also a lead acid battery, sulfation occurs here as well. The question of can you desulfate an AGM battery can be answered as Yes, you can. To keep your battery healthy and increase the lifespan you have to have regular inspection. 

And, when needed you must recharge the battery followed by desulfating the battery. Doing this on a routine basis will keep your AGM battery safe from desulfation.

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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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