Sulfate the battery refers to the process of lead sulfate crystals forming on battery cells over time in all types of batteries. This can be caused by a number of factors, including prolonged storage, overcharging, or undercharging. Sulfation is a major cause of premature failure of lead-acid batteries. Sulfated batteries often appear gray and worn, making it difficult to tell the cells and separators apart. In this EDC article, we will look at the causes of battery sulfation and how to prevent it.

Which batteries are most likely to experience sulfation?

Sulfation is most common in lead-acid and AA batteries. These types of batteries are more prone to lead sulfate formation due to their chemical structure and the reactions that occur between the electrodes and the electrolyte.

In lead-acid batteries, sulfation occurs due to the reaction of the lead electrodes with the sulfuric acid in the electrolyte. This process is intensified when the battery remains in an incompletely charged or completely discharged state for a long time.

Over time, lead sulfate crystals form on the electrode plates, and these crystals are difficult to reverse. The result of this process is a decrease in the capacity and power of the battery, which can ultimately lead to its complete failure.

In pen batteries, sulfation is also very common, especially in devices where the batteries are used continuously and for long periods of time or are stored in humid and hot environments. This problem occurs due to the formation of sulfate compounds on the battery terminals and can lead to reduced electrical current, poor performance, and even chemical leakage from the battery.

What causes battery sulfation?

The main cause of battery sulfation is the chemical reactions inside lead-acid batteries, during which lead sulfate forms on the surface of the plates. This phenomenon occurs when the battery is continuously undercharged or left in a state of prolonged discharge. The following are the main causes of battery sulfation:

Incomplete or insufficient charging: When the battery is not fully charged, sulfates gradually form on the plates and prevent the correct chemical reaction from taking place. This is common in car batteries that are left unused for a long time.

Overdischarge of the battery: When the battery is deeply discharged and left in this state for a long time, the chemical reaction becomes permanent instead of reversible, and the sulfates form a crystalline form that is resistant to recharging.

Inappropriate temperature and environmental conditions: High ambient temperatures can increase the rate of chemical reactions inside the battery and accelerate the sulfation process. High humidity can also lead to increased sulfation at the battery terminals.
Prolonged battery storage in a low or discharged state: Batteries that are stored in a partially charged or discharged state for long periods of time are more susceptible to sulfation. This condition is common in emergency batteries or batteries in vehicles that are rarely used.
What are the signs and symptoms of battery sulfation?

Battery sulfation is accompanied by symptoms that indicate that the battery is no longer able to perform optimally. Some of these symptoms include the following:

Not holding a charge or not accepting a charge: Batteries that are sulfated cannot hold a charge well or sometimes even not charge at all. This is one of the most common signs of battery sulfation.

Premature battery discharge: If the battery discharges much earlier than expected, it indicates a buildup of sulfates, which prevents chemical reactions from taking place properly.

Reduced power output: Sulphated batteries are often unable to provide enough power to electronic devices, and as a result, the battery’s performance is greatly reduced.

Reduced battery voltage: Checking the voltage with a special device is a sure way to detect sulfation. A voltage of less than 12.6 volts can be a sign of sulfation.
Decreased electrolyte density: The density of the electrolyte in sulfated batteries decreases, which also reduces battery performance.
Increased charging voltage and failure to accept a full charge: In a sulfated state, the battery’s charging voltage increases and the battery has difficulty accepting a full charge.
Change in the appearance and structure of active materials: In sulfated batteries, the internal plates may change color or become sandy, which is a sign of damage to the active materials.
Swelling of active materials: Sometimes, sulfation causes the active materials to swell, and this is also a sign of reduced battery life.
Types of sulfation

Sulfation in lead-acid batteries is divided into two main types: reversible sulfation (soft) and permanent sulfation (hard). This division is based on the effects of sulfation on the battery and the possibility of its return to its original state.

Reversible (soft) sulfation: This type of sulfation occurs in the early stages and is reversible. If battery sulfation is detected and treated early, specific procedures can be used to remove this type of sulfation and restore the battery to optimal performance. This should be done by a qualified professional with special equipment, as otherwise it may cause overcharging and dangerously high battery temperatures.
Permanent (hard) sulfation: This type of sulfation occurs when the battery is left in a low-charge state for a long time. This usually occurs after weeks or months without proper charging. In this condition, sulfate crystals permanently form on the battery plates, reducing the battery’s capacity and lifespan. Restoring the battery to its original state is very difficult in this type of sulfation, and in most cases the battery needs to be replaced.

Special testing devices are used to diagnose the type of sulfation and the possibility of returning it to its original state. By connecting this device to the battery, the voltage discharge curve is observed. If the battery can maintain a stable voltage during discharge, there is a possibility of recovery. However, if the voltage drops rapidly, the battery is most likely damaged due to permanent sulfation.

How to prevent battery sulfation?

One of the easiest ways to prevent battery sulfation is to maintain it properly. Even if the battery is fully charged, it should be kept in a charged state and its voltage should not be allowed to drop below 12.4 volts. Keeping the battery at the right temperature is also important, because for every 10 degrees of increase in temperature, the battery discharge rate doubles.

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Other ways to prevent this problem include:
Regular battery charging: Batteries, especially lead-acid batteries, should not be left without charging for long periods of time. The best way to prevent sulfation is to charge the battery regularly and fully. Excessive and prolonged battery discharge accelerates sulfation.

Avoid deep discharge: Try to avoid completely discharging the battery, as deep discharge leads to the formation of lead sulfate crystals on the battery plates. It is best to keep the batteries charged as much as possible.
Use smart chargers: Smart chargers charge the battery fully and then stop charging. These chargers prevent overcharging the battery and sudden discharges, thus reducing sulfation.
Regularly check the electrolyte level: In lead-acid batteries, a lack of electrolyte can lead to sulfation. Check the electrolyte level regularly and add distilled water if necessary to always keep it at the right level.
Store at the right temperature: High or very low temperatures damage the battery and can lead to sulfation. Store the battery at a moderate temperature and away from extreme heat or cold.
Keep battery terminals clean: Dirt and dust buildup on battery terminals can lead to sulfation and reduced current. Keep terminals clean and, if necessary, use special compounds to prevent sulfate buildup.
Use a charge protector: If the battery is used in devices that are not used for a long time (such as cars that are rarely used), it is better to use a charge protector to ensure that the battery always remains at the proper charge level.
What does blue powder on battery terminals indicate?

Blue or white powder on the battery terminals, especially on the positive pole, indicates that the battery is sulfated. This powder is lead sulfate and is formed by the reaction between the terminal metals and the electrolyte. In addition to reducing the electrical current, the presence of this powder increases the battery resistance, which ultimately reduces the battery’s lifespan.

How to remove and clean sulfation?

Cleaning the terminals: To clean the sulfates, you can use a solution of water and baking soda. Dip a small brush in the solution and gently brush over the sulfates. This will remove the sulfates.
Using an anti-sulfate spray: There are special sprays for cleaning battery sulfates that, in addition to cleaning, prevent the formation of new sulfates.
Final words

In general, choosing a reputable brand and a quality battery can reduce the likelihood of sulfation and increase the useful life of the battery. However, proper care and maintenance are also of great importance so that you can get the best performance from your battery.

Using the best raw materials and the latest production technologies, the ADC brand offers high-quality batteries that have excellent resistance to sulfation. Buying an ADC battery means extending the useful life of your devices and reducing problems caused by battery sulfation. For more information and expert advice, contact our experts.

Frequently Asked Questions
Is battery sulfation reversible?

In some cases, if sulfation is detected early, it can be reversed. This is called reversible sulfation. However, if sulfation is severe and permanent, it will be difficult to restore the battery to its original state and the battery may need to be replaced.

Does frequent battery charging cause sulfation?

No, frequent charging alone does not cause sulfation. In fact, keeping the battery fully charged is one way to prevent sulfation. However, if the battery is always left in an incompletely charged state or is stored for a long time without charging, the likelihood of sulfation increases.

How does temperature affect battery sulfation?

High temperatures can accelerate the sulfation process. Batteries stored at temperatures above 75 degrees Fahrenheit are more susceptible to sulfation. Lower temperatures also increase the likelihood of sulfation, so it is recommended to store batteries at a moderate temperature.