How To Recondition Lead Acid Battery With Epsom Salts

We live in a world where we’ve somehow been conditioned to throw away things once they stop functioning or when we notice a decline in their overall performance.

Take your lead acid battery, for example, how many of these batteries have you thrown out or have then gathering dust somewhere in the garage?

In as much as no one wants battery problems, whether we are talking about lead-acid batteries for cars or lawnmowers, the truth is that your battery isn’t really dead when they tell you it’s dead.

A dead battery or an old battery shouldn’t be thrown out just because it appears dead because you can actually bring it back to life easily, thanks to a process called reconditioning or the disulfate process.

This process allows you to rejuvenate the lead-acid battery and bring it back to 100% functional capacity.

This means that in as much as the lawnmower’s battery is the most expensive and the critical component of the machinery; it could serve you for a really long time if you take good care of it and if you know how to recondition it.

To help you understand the whole battery reconditioning process, we’ll first take a look at why reconditioning is the process that would allow you to bring the battery back to life.

Why reconditioning?

car battery

In other words, why does a lead-acid battery die?

Nature dictates that anything that is not used frequently loses some of its function unless it’s serviced or repaired frequently, even in man-made items, all thanks to the forces of wear and tear, which cause depreciation.

In the case of the lead-acid batteries, after use for a long time or if you don’t use the battery actively, for example, in winter when the lawnmower is not in use, the function of the battery deteriorates.

Often, this deterioration means that that the battery is unable to hold a charge, and this is what we all refer to as a dead battery.

What you may not know is that the deterioration happens because the internal plates of your batteries will react with the battery’s electrolytes, forming lead sulfate. 

The lead-acid batteries also take the name wet cell batteries, and each of these cells is made of a lead plate that is slightly different, sitting in an electrolyte or a fluid that contains sulfuric acid and distilled water.

In which case, if the level of the electrolyte is too low, then the lead plates will be exposed, and sulfation takes place. Note that Sulfation represents the process in which there is a hard lead sulfate compound deposited around the battery’s lead electrodes – this process takes place when the battery is discharged, and the lead which is on the positive plate reacts with sulfuric acid. 

The lead sulfate accumulates in crystal form, harboring the ability of the plate to charge.

When this happens, there is a resultant restriction in the flow of electrons from one plate on the side to the other plate; hence the inability of the battery cells to charge/ retain a charge.

One of the obvious tell-tale signs of a battery that isn’t retaining charge is the battery not being able to start the lawnmower/ car, yet you remember having a fully charged battery.

Generally, the hardening of the lead sulfate crystals will cause a chemical imbalance in the electrolyte (sulfuric acid and distilled water). To bring the battery back to life/ rejuvenate it so that it can charge/ retain a charge, the accumulated lead sulfate crystals have to be dissolved/ removed, hence reconditioning.

Benefits of Reconditioning Lead Acid Batteries

For starters, reconditioning a lead-acid battery allows for the preservation of the function of the batteries. The reconditioning process gives the battery a refresh option, which allows the battery to run as it did when it was new, leaving the battery with an ample amount of charge.

Obviously, this saves money, especially if you take the safety precautions seriously, and also because you won’t have to buy a new battery. The essentials for the reconditioning process are rather affordable.

The other benefit of reconditioning batteries is to the environment. With fewer ‘dead’ batteries thrown out, reconditioning is an environmentally-friendly process.

Keep in mind that recycling the batteries is very difficult, and most of the older batteries often end up in trash bins and wastelands where the toxic chemicals in the acid batteries leak to the soil and water bodies, causing a huge impact on the environment.

The other reason why we recommend reconditioning of the lead-acid batteries is the process is quite convenient, and you won’t have to buy new batteries after every few years. And since you don’t need to pay someone for the battery’s reconditioning, you will save time and more money in the process.

Risks of Reconditioning Lead-Acid Batteries

Even though reconditioning offers numerous benefits that make it the go-to solution for anyone looking for ways to salvage their lead-acid batteries, there are risks involved. 

And knowing what you are up to will help in determining whether the risk is worth it or not. So, before you start the reconditioning process, here are some of the risks and precautionary measures you should be aware of. 

Remember that the main electrolyte in a battery is sulfuric acid, and this is one of the most dangerous of acids around, which means that you should be able to handle the acid and the battery correctly.

So, the first things that you must do is to invest in some of the best safety equipment, from hardy safety glasses to corrosion-resistant gloves. And even with these items, you need to be careful when handling the battery to make sure that that this battery acid doesn’t leak and burn your skin.

You also need to be aware of the fact that the battery might explode in some conditions, especially when treated poorly or mishandled. That said, there are things that should tell you that the conditioning is not going to work, and you should attempt the process, and if you do, you risk significant damage to yourself and others. We are talking about a battery that’s physically damaged, cracked, or a leaking battery.

If you notice any of these, you should dispose of that battery immediately. 

Such batteries are unsafe and beyond repair. It’s important to remember that before you start the reconditioning process, you need to make sure that the electric cells and the plates of your battery are fully functional and undamaged.

Note that the buildup of lead sulfate is normal and to be expected. However, damage to the battery, in any form, could mean increased risk, and you shouldn’t recondition it.

Lastly, you need to know that in as much as the reconditioning process will save you money by giving the battery a new lease of life, you shouldn’t recondition the battery more than 3 o 4 times.

Eventually, the battery will wear out even with reconditioning, and there will a high rate of diminishing returns. So, while the reconditioned battery will last a number of years as you work on it, it will lose its functionality and get worse with time.

At some point, reconditioning will be of more harm to the battery, and you need to know when to stop – for example, if it loses charge too often and too soon after reconditioning or if it starts to leak.

Having a dead laptop battery, doesn’t necessarily means it’s the end of it’s life. 

How to Identify Bad Battery Cells

recondition car battery

Before the desulfation of the reconditioning process, the first thing that you should do is to identify the cells that are bad. You want to be certain that the reconditioning will work because the battery only needs a nudge in the form of desulfated plates.

To test the state of the battery cells, you need to follow these steps:

  • First off, charge the battery fully, for a minimum of 12 hours. Once the battery is fully charged, disconnect the battery from the charger then allow it to sit/ rest for 10 minutes before working on it.
  • After it’s rested, open the battery’s caps. Check the user manual, or Google is the lead-acid battery is sealed.
  • Next up, fill up each section to the water level suggested with distilled water. Note that this is a crucial process. Sparks are created in each of these components, and if left empty, the sections will be filled with hydrogen and oxygen, which could result in a very explosive reaction that would be hazardous because it would send the acid in the battery flying everywhere. The higher level of distilled water in the battery means less or no empty room for hydrogen and oxygen to buildup in, hence a lower risk of the battery exploding right in your face. Make sure that the water level is accurate using a flashlight.
  • Once this is done, you’ll need to measure the voltage of the battery’s terminal to confirm that it’s fully charged. A 12v battery will have terminal voltage readings of between 11.8 – 13v. If the reading is below 11.8v, it means that there is a cellular imbalance from a cell that isn’t working right.

With this information, you’ll want to measure the voltage of the problematic cell. To do this, you need to dip one end of your multimeter probe into the cell solution, then attach the other end of the probe to the terminal.

The cell’s voltage should be 1/6th of the total battery voltage – a 12v battery will have at least 2v in each cell. The cell whose numbers are too low is the problematic one. 

Besides the voltage for the cells, you could also identify the problematic cell from color differences. Cells with a lead sulfate buildup are not conductive, and they will have a different color from the conductive cells.

Reconditioning a Lead Acid Battery With Epsom Salts

reconditioning car battery

There are different methods for lead-acid battery conditioning, but the use of Epsom Salts is one of the most effective methods. Epsom salt or magnesium sulfate is one of the most effective chemical desulfators that will dissolve the sulfation, rejuvenating the old battery.

Some of the reasons why the use of Epsom salts is recommended when it comes to reconditioning batteries include:

  • Significant cost savings, and you would earn money by conditioning your neighbor’s batteries.
  • It reduces waste and keeps the environment safe.

Equipment Needed

  • Protective gear – apron, goggles, non-corrosive/ chemical-resistant gloves, and any other safety equipment
  • A battery charger
  • A voltmeter
  • Plastic funnel
  • Tool kit with screwdriver
  • 2 large plastic buckets
  • Distilled water
  • 1 pound of Epsom salts
  • A pound of baking soda
  • Toothbrush
  • Steelwool

Steps for Reconditioning Lead Acid Battery

Step 1 – put on safety goggles and glasses and gloves

 You need to ensure that these items are chemical resistant and in excellent condition.

Step 2 – Preparing the Battery

The first thing that you need to do before you begin the reconditioning is to clean the battery terminals. You must have your gloves on. Clean the terminals thoroughly in case of corrosion.

You need baking soda with distilled water in a runny paste form to clean the terminals.

Apply this paste on the terminals, let it sit for a few minutes then use steel wool to clean off the area. You could use a toothbrush to scrub the corrosion stains are too stubborn.

Keep in mind that foaming is not a bad thing as it indicates that the cleaning is working. Wash down the terminals using a little more baking soda and water then wipe it down when satisfied.

Allow the terminals to dry completely.

Step 3 – Check the battery’s voltage

Use your voltmeter and follow the steps above on identifying bad cells to check for bad cells.

Now, to check if the battery is holding a charge, use the terminals voltmeter readings to check the state of the battery. Note that if the voltmeter reading is 0, it might mean that the battery suffered a short-circuit, and it needs replacement.

Step 4 – Empty Your Battery

Keep your goggles and the gloves on. This is the most important and also the riskiest part of the reconditioning process, and you need to be safe. If you are certain about your safety, you need to get your screwdriver to get under and open the battery’s caps.

The caps should come off easily when given a small nudge. Take one of the larger plastic buckets and pour the battery acid into the bucket.

When pouring the acid, you need to make sure that that acid is tilted away from you. Also, it would be a good idea to wear corrosion-resistant and industrial-grade gumboots.

Be very careful here and avoid spills. After you’ve emptied the battery cells, put it on the ground upright. Then pour half the baking soda into the old acid you’ve poured from the battery to neutralize the acid.

Step 5 – Cleaning the Cells

Cleaning the Cells

Now that the cells are empty, you need to clean the cells – think of this as half the reconditioning process. So, mix half a gallon of your distilled water with the remaining half of the baking soda.

Mix them well, then pour some of the mixtures into the cells using the plastic funnel. Once each cell is full, put back the caps and try shaking the battery gently from side to side.

Do this for a couple of minutes, then open the caps as you did earlier, the pour out this mixture into a plastic bucket. The battery is now ready for reconditioning.

You can dispose of the waste cleaning liquids.

Step 6 – Reconditioning

Here, you need to refill your battery cells, and you will need Epsom Salts and distilled water this – think of this mixture as your new electrolyte. The Epsom salts-distilled water mixture will raise the voltage and also the amperage of the battery, as it stops the sulfating process on the plates.

For this, your mixture will be made of boiling distilled water and Epsom salts.

The easier approach is, therefore, the combination of the  Epsom salts with the boiled distilled water in a clean, plastic bucket. Add the Epsom salts while stirring.

Your electrolyte mixture is ready when the hot water is clear. Using a clean plastic funnel, pour the mixture into each cell, until they are all 100% full. Save the leftovers for next time.

Put the battery caps back on and then shake the battery for a few minutes. When done, the battery will be ready for charging.

Step 7 – Charging the reconditioned Battery

Charging the reconditioned Battery

The next crucial step is to charge the newly reconditioned battery. For this step, you need to remove the caps first – a move that prevents the electrolyte solution from overflowing or heating up.

Note that pressure buildup in the battery is both troublesome and a safety issue. Before charging, you also need to make sure that the charger is far away from your battery, as possible.

When ready, connect the battery’s positive lead to the positive terminal of the battery. Do this for the negative side too. Allow the battery to charge slowly for about 36 hours.

And don’t forget to read the manufacturer’s instructions on charging and the battery’s charger.

Step 8 – Testing the Battery

Testing the Battery

Using your voltmeter, test the battery. If the reading is over 12.43v, the battery is ready, but is the voltmeter readings are below 12.43v; you need to allow the battery to charge for 12 more hours.

If there is an electrolyte overflow, refill the cells. Once satisfied with the readings, you can retest the battery. Remove your battery charger, put the caps back on, then connect the battery to the car/ lawnmower.

Switch on the beam (without starting the car) and then let the battery run on load for some minutes. Test the voltmeter again. The battery will be fully reconditioned if the voltmeter reads 9.8v or more.

If less than 9.8v, the reconditioning is incomplete, and you need to repeat the steps above.

Alternatively, you could cycle the battery – if it fails the load test. In this case, you need to discharge your battery completely before recharging it.

Draining the battery is as easy as connecting it under load and leaving the beams on. Cycling is a lengthy process, though, and you might have to cycle the battery at least 4 or 5 times for the results you want.


These are the safest and the best steps for you to follow when reconditioning your lead acid battery.

Just make sure that you adhere to the safety precautions as advised above because battery acid is corrosive and it might burn your skin or eyes, and eat through clothing; the battery emits hydrogen gas which might cause an explosion in the presence of oxygen; there is a risk of electric shock from the batteries if they spark; finally, some batteries are quite heavy, and you need to be extra careful when handling them.