What Causes A Sulfated Battery? Signs And Solutions

Batteries are quite prone to sulfation. During the whole life of a battery, sulfation will happen to some extent. But, more storage, overcharging, or undercharging of a battery can result in fast sulfation. The more sulfate that accumulates on a battery cell, the less efficient the battery gets. 

But what is sulfation? What is the leading problem of sulfation?

The phenomenon of lead sulfate crystals forming on a battery cell is known as battery sulfation. Sulfation is the leading reason for premature failure in lead-acid batteries, and it can result in different other issues.

Let’s Learn in details below.

How Do You Know if a Battery is Sulfated?

If you have a sulfated battery, you might observe indicators of decreased performance. The most typical symptom of a sulfated battery is a battery that does not charge properly or at all.

If you think that your electrical devices are not getting enough current (weak a/c, dim headlights), this is a significant indication that the battery is sulfated. 

When your battery dies much sooner than expected, sulfation is likely to be the cause. A multimeter may be used to determine the battery’s standing voltage.

If your battery has less than 12.6 volts, it is undercharged, probably due to sulfation.

A visual sulfation test on the cells of the battery is also an option. This will necessitate the removal of your battery, therefore perform it on a covered area in a well-ventilated environment.

Using a flat head screwdriver, cautiously detach the battery top caps. 

You must be able to see the battery cells, isolator, and electrolytes levels by looking into each aperture.

Cells and separators in a normal sulfated battery may be gray, dirty, and difficult to identify from one another.

The silver-lead cells inside a good battery will be fresh and distinct from the black separators. A visual representation of battery sulfation is provided here.

What are the Types of Battery Sulfation?

In lead-acid batteries, sulfation can be reversible or permanent. Luckily, their titles are self-explanatory and refer to the consequences of sulfation on the battery. 

If sulfation is detected early enough, it is occasionally possible to reverse the sulfation of the battery.

However, this must only be done by an experienced expert because it may require overcharging the battery and raising the battery temperature.

There has been some investigation into reverse charging for the recovery of sulfated lead-acid batteries.

On the other hand, when a battery is left in a poor state of charge for an extended period of time, permanent sulfation occurs.

At this point, restoring the battery or reversing the sulfation is exceedingly unlikely, and the battery must suffer the consequences of irreversible sulfation.

What Causes a Sulfated Battery?

Sulfation happens when a battery is not fully charged; it accumulates and lingers on the battery cells. When there is excessive sulfation, it can inhibit the chemical to electrical transition and have a significant influence on battery efficiency. If sulfates accumulate in your battery, the following can occur:

Charging times become longer, shorter running intervals between charges, high heat buildup, severely reduced battery life, or total battery failure

As part of the normal chemical procedure of a battery, every lead-acid battery eventually collects sulfation over time. However, sulfation accumulates and causes issues when- a battery has been overcharged, a battery is kept at temperatures above 75 degrees, a battery is kept charged but not fully charged.

Can Battery Sulfation be Reversed?

Now, if your battery has sulfation and it is reversible, here are some steps you can follow to get rid of it.

Step 1:

Take the plastic coverings from the tops of the battery cells and set them aside.

Based on whether you have a 6-volt or 12-volt battery, you will find three or six covers.

With your fingers, remove the covers. Put a screwdriver on the screwdriver holes and undo the covers.

Step 2:

Examine the battery cells. To check, you would have to use a torch. In every battery cell, search for the two markings on the walls.

The point closest to the top represents the max fluid level, whereas the lower mark represents the minimum. Sulfation happens when the fluid level falls under the minimum.

Sulfation may be seen on the plates, which resembles corrosion on metal although is yellowish because of the sulfuric acid in the cells.

Step 3:

Gently pour distilled water inside every cell. Replenish the cells up to the maximum marking, but not any higher.

Leave room for the fluid to swell, which occurs while a battery charges. Do not change the battery cell coverings.

Step 4:

Attach the gripper to the positive terminal at the end of the red positive battery line from the battery charger. It’s commonly denoted by the letters “+” or “Pos.” Insert the clamps at the tip of the black cable into the negative battery terminal marked “-” or “Neg.”

Step 5:

Adjust the charger to recharge at the minimum voltage possible. The term “trickle charge” may be used to describe it. High charge settings will not adequately eliminate sulfation from the lead plates, therefore don’t use a rapid or boost charge.

Step 6:

Connect the charger to the power source. Set the charger to charge.

Check if the light is activated, indicating that the battery is charging. Ensure the meter is reading a low charge if it has one.

Step 7:

Allow the battery to charge slowly for 36 hours. The distilled water that is put into the cells should turn into sulfuric acid when the battery charges.

The sulfation on the lead plates should be progressively removed by the acid.

Step 8:

After 12 hours, inspect the battery. Examine the cells. Tiny bubbles should rise, indicating that the batteries are charging.

If you place your palm on the battery’s wall, you will notice that it is warm.

If one or more cells aren’t creating little bubbles, it’s conceivable that the cell is broken beyond repair; nonetheless, sit tight till the charging period is up.

Step 9:

After 36 hours passed there should be lots of tiny bubbles inside the battery. That means the reversing process has worked. Otherwise, the battery is beyond repair.

How to prevent battery sulfation?

Appropriate battery storage is among the simplest strategies to avoid battery sulfation. A battery should be charged sufficiently to keep it from going below 12.4 volts while it is stored.

Sulfates will be prevented from accumulating if this maintenance fee is applied.

It’s also worth noting that, while we previously said that batteries should not be kept at temperatures beyond 75°F, the speed of self-discharge doubles per 10°F above ambient temperature.

Battery sulfation avoidance does not have to be a difficult task. All it takes is frequent battery maintenance and adhering to charging recommended practices.

The most important reason for not storing the battery with a depleted charge is sulfation. Because reversing the consequences of lead plate sulfation is exceedingly unlikely after it has begun, it is vital to take care of it from the outset.


Sulfation is quite problematic for the battery and the devices used with that battery. It can damage both if left unattended. Thus, always take good care of your battery and electric devices. 

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