Do AGM Batteries Need To Be Equalized?

Equalization of lead-acid batteries falls in the regular maintenance program. It is an important step to be followed to prevent the battery from being deeply discharged. Hence, to keep the battery healthy and amperage output consistent equalization is required. 

Now, the AGM battery is also a part of a lead-acid battery being an electrochemical battery. The question arises, do AGM batteries need to be equalized or not? 

Like most lead batteries, sulfation also takes part in the AGM batteries. But, the rate is very negligible. That is why AGM batteries are called maintenance-free batteries. Equalization can be done in AGM batteries but some conditions must be followed.

What exactly does it mean by equalizing a battery?

Equalization of a battery is a combination of some actions. Basically, it means recharging and desulfating the battery. Lead-acid batteries effectively suffer from sulfation. SUlfation is a process of creating a layer of Lead-Sulphate precipitate on the electrode plates. 

It is a common phenomenon because in the electrolyte there are free ions of Lead and Sulfate. Their equivalent but opposite oxidation number enables them to create a precipitate of Lead-Precipitate. The lead sulfate is easy to break by recharging the battery to 100%. If you fail to recharge the battery regularly, a strong layer of lead sulfate will be created.

Is it necessary to equalize the AGM battery?

Even though the AGM battery contains an absorbed form of electrolyte. It also follows the basic principle of lead-acid batteries. Like all other electrochemical batteries, AGM batteries also pass through the process of sulfation. But it does not happen on a regular basis.

Discharging the battery deeply causes more sulfation. The deposition of the lead sulfate on the lead plates causes an interruption in the empower production. If you do not recharge the battery regularly the scenario becomes worse. Because the precipitate of the Lead-sulfate hardens with time.

AGM batteries have 50% depth of discharge. This means the AGM batteries are sensitive to the discharge rate. That is why it is necessary to equalize the AGM battery on a routine basis. Not all AGM batteries require equalization though. It is better to consult with the manufacturer to seek permission for equalizing the AGM battery.

By equalizing the battery the ratio of the lead and sulfate ion in the electrolyte can be kept at an optimum level. Besides, you can prevent the AGM battery from falling into the trap of deeply discharging. AGM batteries being deeply discharged causes a malfunction in the battery power production. It can also become permanently damaged due to deeply discharged and over-sulfation.

Equalizing prolongs the Battery Life

Your AGM battery’s health can be maintained by equalizing the battery. The longevity of the battery can be prolonged by regular maintenance. It can enhance the charge holding capacity of the AGM battery.

Higher Power Output rate

You will get a higher output of power by equalizing the battery routinely. The efficiency of the electrode increases by equalizing the battery. Precipitation of Lead-sulfate on the Lead plate can be avoided. In electrolytes, the balance of the positive and negative ions can be maintained. Thus, no interruption can be seen in the movement of the free electrons to carry the current.

Lower Rate of Discharge

The rate of discharge in the AGM battery should not get below 50%. Sulfation and lack of charging the battery drastically reduce the state of charge. The alternator of a vehicle is not efficient enough to ensure a 100% state of charge of the battery.

Equalizing the battery ensures the SoC of the battery remains as stable and high as possible. Moreover, it prevents the battery from being discharged quickly. Therefore, you do not have to kick start the battery after a long period of time. 

The process of Equalize AGM Battery

Equalizing an AGM battery is sensitive. Because it involves the input of voltage to the battery. An AGM battery is very sensitive to higher voltage input. 

Desulfation of the Electrode Plates of the AGM battery

Overcharging the AGM battery damages the cells of the battery. That is why the following steps should be followed.

  • Firstly, disconnect all the appliances from the battery.
  • Plug out all the cables to and from the battery.
  • Unscrew the holding frame and pull out the battery to keep it in a very well-ventilated place.
  • Using a soft piece of cloth or steel wool, scrub the terminals to remove the corrosion.
  • Connect the battery’s positive terminal and negative terminal with the positive and negative cables of an Automated Smart Battery Charger.
  • Plug the battery charger into the wall socket.
  • You find a specific option on the charger saying desulfation. This option actively removes the sulfation of the battery. Most of the modern battery chargers have this option.
  • Turn on the process and wait for a while for completion.

Recharging the Battery

The second step of the equalization process of the AGM battery is recharging. This process is highly sensitive and requires constant inspection. Moreover, AGM battery-specific procedures should be followed to avoid damaging the battery.

  • First of all, connect the battery to the specified smart battery charger.
  • After that, select the charging profile specific for the AGM battery.
  • Set the amperage between 2-10amps for slow charging. This is known as equalization charging.
  • If the battery needs quick charging then amps settings should be between 10-20 amps.
  • Use a voltmeter to keep track of the voltage reading and state of charge of the battery.
  • It may take between 6-7 hours to completely charge the battery.

How much time does it take to equalize the AGM battery?

Equalization of batteries requires a series of actions. For AGM batteries desulfation and equalization charging is done to equalize the battery. The desulfation process takes up to 3 hours maximum. It depends upon the amount of deposition of the precipitate.

After the equalization charging may take 5-6 hours for the AGM batteries. If it is deeply discharged then it may take more time to recharge the battery to a higher state of charge. Therefore, combining the times we can say that it can take up to 8-9 hours for complete equalization of the battery.

How frequently should you equalize AGM batteries?

The Absorbed Glass Mat or AGM batteries are known as maintenance-free batteries. It is because the rate of sulfation is negligible in the AGM batteries. But, the depth of discharge of the AGM battery is 50%. The alternator of the vehicle is strong to recharge the battery to keep the state of charge up to date.

That is why you have to perform the equalization of the AGM battery after a few months. It should be done on a regular basis. Lack of equalization may cause deep discharging of the battery which damages the internals of the battery.

Frequently Ask Questions

Here, we shall learn about the frequently asked questions about the equalization of AGM batteries by consumers.

Do AGM batteries get sulfated?

Like all other lead-acid batteries, AGM batteries also get sulfated. But the rate of sulfation is very low. It is because of the cell construction type. The AGM separator absorbs all the electrolytes. And hence, there remains no liquid electrolyte that promotes sulfation. 

Do you need to add water to AGM batteries?

Adding water or refilling cell chambers of the AGM batteries is strictly prohibited. This may completely damage the battery performance by destroying the cell structure. Therefore, you must not add water or any other substance to the AGM battery.

Why does my battery charger say Sul?

If your battery charger says Sul on the labeling or on the panel, it means it has the option to perform desulfation of the battery. It is an important option that will help you easily remove the sulfates from the battery. It is done by breaking the Lead-sulfate and converting them to free ions.

How can you tell if a battery is sulfated?

If your battery is highly sulfated, you won’t be getting the expected power output. The charge holding capacity reduces. Even the voltage output becomes minimal due to the deposition of the lead sulfate on the electrodes. 


Equalization is the maintenance process of the lead-acid batteries. Gel batteries, standard batteries, AGM batteries are all lead-acid batteries. Therefore, little or more all batteries have some sort of equalization. It enhances battery health and performance.

For AGM batteries, it is imperative to consult with the manufacturer. Because not all AGM batteries are certified for the equalization process. 

On the other hand, following equalization may cause damage to the battery. If all is okay, then the AGM batteries should be equalized on a regular basis. The process is easy and can be completed by using smart battery chargers. 

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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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