How To Recondition Lead-Acid Batteries: Best Methods Explained

Lead-acid batteries are specially designed for cars and other four-wheeler vehicles. Lead-acid batteries are the most dependable form of power source for the automobile industry. Today, we’ll be talking about ‘how to recondition Lead-Acid batteries’.

Lead-acid batteries are in existence ever since the late 19th century. They’re well known for their low-cost and high-performance capability.

These batteries are highly efficient, are easy to recondition and provide a long lifespan – as long as twelve months for their one cycle.

About Lead-Acid Batteries

The lead-acid battery was the first rechargeable-type battery that the world had known. It was discovered in 1860 by a French physicist Dr. Plante

Even today, lead-acid batteries are in the primary applications of the automotive and wheeled stationery industry. 

If you see the composition of a lead-acid battery – it is a composition of lead, a lead dioxide submerged in an electrolyte made of sulfuric acid and water.

Lead-acid batteries can be categorized into two:

The flooded-type is also one of the most cost-efficient and is the most commonly used for automotive and industrial applications.

 The sealed-type also known as ‘valve-regulated-lead-acid’ (VLRA) which has recently been implemented for various power supplies and stand-alone power supply for villages and remote locations. 

Although lead-acid batteries are widely known for their cost-efficiency, performance and easy reconditioning, but just like any other battery it is prone to ‘memory effect’.

Memory effect is when after the first recharge cycle, the battery remembers it and there is a considerable voltage depression after the second or third recharge.  

What Are Lead-Acid Batteries?

Even before 1860, it was Nicholas Gautherot who observed that wires that were used for the electrolysis experiment provide a certain amount of secondary current when disconnected from the primary power source in 1801.

Although, in 1859 Gaston Plante’s lead-acid battery was one of the first ones which could be reconditioned passing a reverse current through it. 

If you deconstruct Dr.Plante’s model – it comprises of two lead sheets that are separated by rubber strips and are rolled into a spiral. His battery model came into use for powering train lights, when stopped at stations.

As time went by, Plante’s model was ineffective when it came to mass-production. In 1881, Camille Alphonse Faure created a differently designed lead-acid battery which had lead grid lattice, into which a lead oxide paste was pressed in the shape of a plate.

A lead-acid battery always has a gel-type electrolyte which enables it to be used at any position without any threat of leakage and dripping. 

Construction of Lead Acid Battery

If you break the term ‘lead-acid battery’ it consists of three things – it has lead, acid and is a battery. Lead is a soft and malleable element, abbreviated as ‘Pb’.

We all know what an acid is, acid are substances that can either donate a proton or accept an electron pair. In general, a lead-acid battery constitutes of lead and anhydrous plumbic oxide (also known as lead peroxide). 

Every battery consists of two plates, namely the cathode (negative) and the anode (positive). In a lead-acid battery, the anode is made up of lead dioxide and the cathode is made up of spongy and porous lead

Both the electrodes are separated by a separator which is made up of insulating material. The electrolyte constitutes of sulfuric acid and water. All of this is kept intact in a hard plastic case.

How To Recondition Lead-Acid Batteries?

The reconditioning process of a lead-acid battery, which is generally known as a 12V car battery is a bit tedious and one needs to have all the tools necessary to carry out the process. Given below are list of tools that one must-have for the reconditioning of a lead-acid battery. 

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  • Safety Goggles.
  • Neoprene Chemical Resistant Gloves.
  • Apron (to protect your clothes from spillage).
  • Battery Charger.
  • Flathead Screwdriver.
  • Plastic Funnel.
  • A Gallon of Distilled Water.
  • 0.5 – 1lb Epsom’s Salt.
  • Plastic Bucket.
  • Voltmeter.
  • 1lb Baking Soda.
  • Battery Hydrometer (optional)

Step 1: Preparing For Battery Reconditioning

clean the battery terminals

In the first step of reconditioning, you will need to clean the battery posts (terminals) as there will be corrosion built-up on the battery posts which need to be cleaned.

For this purpose, you can use a ‘battery posts cleaner’ which quite easily cleans most of the corroded posts present in your lead-acid battery.

You can also create your own ‘battery posts cleaning’ solution. It’s pretty simple, just take 10 ml of water and 2 tablespoons of baking soda and stir until the solution becomes runny.

Now use a spare toothbrush and pour the solution little-by-little on the corroded areas of the battery, you will notice the solution foaming up – which means the solution is reacting with the corrosion and cleaning it up.

If the posts of your battery are heavily corroded, go for a wired brush or steel wool which will effectively facilitate the cleaning process. Using 300-grain sandpaper also works pretty well. 

After the posts of the battery are cleaned it now time to check the voltage of the battery, for which a voltmeter would come to use. 

Connect the voltmeter with your battery, if the voltage reading shows 12.6+ that means your battery is in good condition and it wasn’t working due to corrosion.

If the battery is anywhere showing less than 12.4V that means it requires ‘reconditioning’ and if it shows 0V that means the battery has faced some short-circuiting and won’t come back to life. 

Step 2: Emptying Your Battery Acid and Cleaning Cells

empty the battery acid

The second step includes the removal of the acid present inside the cells and a thorough clean-up of the battery from inside.

For this, take a flathead screwdriver to remove the caps. The battery generally has 2-3 caps. After the caps are removed, carefully remove the battery acid in a bucket.

In order to be safe while handling the battery acid, keep a solution of baking soda + water on the side. Just in case the acid spills, put the solution to neutralize it. 

Once the battery acid is completely removed, it’s time to clean the interiors of the battery. Take the same baking soda + water solution and pour it into each cell of the battery and cap them firmly.

Now, you have to shake and jerk the battery nicely with the solution in each cell. Give the process around 30 – 45 seconds and then, dispose of the solution. Now the battery is clean and ready to recondition.

Step 3: Reconditioning Your Battery

distilled water and Epsom’s salt

After the second step, your battery is pretty much clean and ready for reconditioning. Step 3 involves filling the cells with a new electrolyte made of distilled water and Epsom’s salt.

Filling the battery with a new electrolyte increases the voltage and amperes a battery provides. The process of making the electrolyte is simple.

It is recommended to use boiling water while dissolving Epsom’s salt as the salt dissolves much easier in the boiling water, without much of a hassle.

Once your electrolyte is ready, you need to start filling up each cell with the new electrolyte slowly and gradually avoiding any spillages elsewhere.

Step 4: Charging Your Battery

Charge car battery

Once the cells of the battery are completely filled with the new electrolyte, they need to be jerked and shaken well for about 2 – 3 minutes.

Now, get a good quality battery charger and connect like terminals with like. The positive terminal needs to be connected with the anode and the negative terminal needs to be connected with the cathode.

The charging process takes around 24 – 36 hours after which the battery needs to be tested for voltage reading with the voltmeter.

The precise reading should be around 12.43V after a complete 24 – 36 hours recharge. If the battery shows less than 12.43V or 0V, it needs to either be disposed of or shown to an expert for other ways to bring it to life.


Lead-acid batteries are great for long-term use, a single lead-acid battery gives a lifespan of twelve months, after ‘reconditioning’ you can add another twelve months to it and the cycle goes on.

Reconditioning lead-acid batteries also saves a lot of money and also keeps the environment away from the threats of battery chemicals. 

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