UniEnergy Technologies Battery » How To Desulfate A Battery? (2 Effective Methods)

How To Desulfate A Battery? (2 Effective Methods)

It doesn’t matter whether you own a small UPS system or a huge, expensive car. The sulfation of lead-acid batteries can render your gadgets useless.

Some issues that you may experience include:

  • Long charging times
  • Loss of starting power
  • More heat build-up

And, if a sulfated battery is left untreated, it will eventually fail to work. You will have no other solution than to spend hefty amounts on battery replacement. Of course, this won’t be possible again and again.

So, in today’s post, we’ll show you how to desulfate a battery. This may sound technical and complex, but it isn’t. We were able to do it and so can you!

What is Battery Sulfation?

To understand desulfation, we should first know what sulfation is.

Sulfation is the natural chemical process where lead sulfate crystals build up on the surface. It occurs every time the battery is in use.  However, they’re temporary and disperse during the battery recharge.

The real trouble begins when you leave the battery unattended. By this, we mean that the battery isn’t used for prolonged periods. This causes the lead sulfate crystals to increase in size and become permanent.

As a result, the battery capacity is reduced and a chain of problems is triggered. You’ll notice excessive heating, loss of starting power, and a need for longer charging times. All this means your battery would no longer be efficient.

It may even fail. So, it’s always important to keep a lead-acid battery in constant use. You should also ensure:

  • It is not deprived of full charges.
  • It is not undercharged.
  • It is not stored at high temperatures (above 75 degrees).

In case your battery starts developing permanent sulfation, one should not panic because the process is reversible through desulfation.

Is It Possible to Completely Desulfate a Battery?

Possible to Completely Desulfate a Battery

Desulfation means the removal of sulfate. It is the reverse process of sulfation, though it doesn’t occur naturally. You must perform it to lessen the negative impact of sulfation.

But does it really work?

There are different methods to desulfate a battery. While some are advanced and others old, none gives the guarantee of completely Desulfating a battery.

This is because a battery goes through constant sulfation when it’s used. At most times, you cannot even tell a sulfated and desulfated battery apart by looking at them.

So, keep one thing in mind: desulfation can only help maintain a battery’s condition. In the case of permanent sulfation, the process will improve the battery performance. But, it will not stop sulfation completely.

When Does a Battery Needs Desulfation?

The need for desulfation is evident when the battery isn’t holding a complete charge or isn’t performing efficiently. You will notice a low current supply and high internal resistance.

Large white patches will also start to appear on the battery’s exterior. Here’s an example:

Battery Sulfation
Image Credit: impactbattery

However, sometimes, the battery will show none of these signs. This is when the battery has been left unattended for a little while. In this case, you can ensure the need for desulfation by doing a standing voltage test.

You just need a multimeter for it. Use it to find out the battery’s standing voltage. If the results are lower than 12.6-volts (AGM battery) or 12.4-volts (starter battery), know that the battery is undercharged due to sulfation.

How to Desulfate a Battery?

Desulfation methods

Desulfating a battery is not a simple process in any aspect.

It’s true that there are different methods to perform it, and some may be easier than the rest. But, none are suitable for beginners.

Below, we have explained the two best ways to desulfate a battery. It’s recommendable to ask an expert or professional to use them.

Method 1: Short High-Current Pulses

The large sulfate crystals on the plates can be broken down by subjecting the battery to intermittent, high-current pulses. This is done while the battery is charging. As a result, the rhythmic resonance and high- current makes the crystals split.

However, these electrical pulses should be optimized according to the extent of sulfation. Here are two circuits that are commonly used for the process:

  • PWM Circuit

The PWM circuit stands for pulse-width modulation circuit. This particular layout adjusts the amp output. There’s also an integrated 555 IC timer and two transistors to intensify the IC timer’s output. As a result, high-current pulses are generated.

  • Transformer & Bridge Rectifier Circuit

The transformer & bridge rectifier circuit is a little complex. You’ll need to take care of a lot of things like the transformer rating, resonant frequency, and whatnot.

However, once constructed, the circuit sends 100Hz or 120 Hz powerful pulsating direct current. This instantly breaks the accumulated sulfate from the plates.

If you’re tech-savvy, it’s possible to build these circuits all by yourself and apply the current.

But, if that’s not something you prefer, hire a professional or purchase the best anti-sulfation devices in the market. These gadgets use the same short high-current pulses method.

However, you may find some models that use high frequency. Instead of varying the current or voltage, they adjust the amplitude and waves. The increased intensity causes the crystals to break just as efficiently as in high-power.

Method 2: Epsom Salts

Epsom Salts

Epsom salt refers to a chemical compound that includes magnesium, oxygen, and sulfur. Its formal name is magnesium sulfate.

Typically, Epsom salts are used for relaxing muscles. People add them into the bath water and soak themselves to relieve all kinds of pain. However, Epsom salts work well for the desulfation of batteries too.

Please note Epsom salts can’t be used to Desulfate the batteries of large equipment. You can use this method for cars, UPS, and other small gadgets.

Things You’ll Need:

  • Safety gloves and goggles
  • Measuring cups
  • Thermometer
  • Plastic funnel
  • Epsom salt
  • Distilled water
  • Baking soda for neutralization
  • Heat source


Here’s how to desulfate a battery using Epsom salts:

  1. Secure yourself by wearing safety gloves and gloves. This process involves handling acidic liquid and may result in serious injuries.
  2. Remove the battery from the device. For example, if it’s a car, open the hood and disengage the battery from the system. You will require a screwdriver.
  3. Measure 7 to 8 ounces of Epsom salts, and set them aside.
  4. Pour ½ quart of distilled water into a cup and heat it. The temperature should reach 150 degrees Fahrenheit. It’s best to use a thermometer to measure the temperature before moving on to the next step.
  5. Add Epsom salts into the hot water and wait for them to dissolve. Set it aside.
  6. Remove the battery caps to access the cells.
  7. Check if there’s some remaining liquid inside. If yes, then you must pour it out in a bucket, neutralize it, and then dispose of it. You can use a little bit of baking soda to neutralize the acidic liquid.
  8. Place a plastic funnel on the access to the battery cell, and pour the salts in. Make sure the cells are completely filled with the Epsom salts.
  9. Replace the caps and gently shake the battery. This will ensure even distribution on each cell.
  10. Now charge the battery. You will have to read the particular battery’s manual to know how. Or, a simple way is to visit the manufacturer’s website and contact the support team.

Once done, you’ll notice improved battery performance. Replace it back into the device properly.

Other Methods

We have already discussed the most preferred methods of Desulfating a battery. However, companies keep on inventing different technologies to tackle this problem.

Some other desulfation methods you may come across include STAMP, 555 timers, and Microcontrollers.


How long does it take to Desulfate the battery

1. How long does it take to Desulfate the battery?

The time to desulfate a battery depends on the method. At a minimum, it can take around 3 to 4-hours. But, at maximum, expect to give at least 3 to 4-weeks.

Throughout this process, your battery will be trickle charged. It’s a method in which the battery gets charged simultaneously with the desulfator. This ensures a complete and successful charge.

2. Can you add Epsom salt directly to a battery?

No, you can’t add Epsom salt directly to a battery. Make sure to dissolve it in hot distilled water first.

3. Can you jump-start a sulfated battery?

Yes, you can jump-start a sulfated battery. The battery will revive and function as long as it’s not completely sulfated. In that case, it would fail and must be replaced with a new one.


All in all, battery desulfation is possible and effective. It doesn’t guarantee the complete removal of sulfate crystals, but it removes them to a certain extent.

You can desulfate a battery in different ways. Generally, the Epsom salt method is considered to be easier. However, it’s only suitable for small-scale power systems.

For larger systems, you should try the short high-current pulses method. The consistent bursts of high power cause the large crystals to shake and disperse quickly.

All that said, if you’re a novice with no experience or technical knowledge, we highly recommend you seek professional assistance.

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