How To Recondition Car Batteries

When it comes to the cars, it always holds a 12v car battery which is the most popular] battery that every car has. When your vehicle battery becomes dead then replacing it with the new one is not the option.

12v car batteries are also known as Lead Acid batteries, they are derived as a lead-acid because this has Sulphuric Acid and Lead Terminal as an electrolyte.

Learning how to recondition car batteries will save you money and time. The majority of us have experienced a dead car battery at least one time in our lifetime. Trying to find out the cause can prove to be frustrating. There are a number of scenarios that can lead to your car battery being drained.

Many situations can cause a car battery to become bad, weak, or dead. You should know how to tell the difference between a bad battery, and one that may be salvaged.

To recondition a car battery you need:

  • Plastic Funnel
  • Safety Glasses
  • Voltmeter with probes on it
  • Common Screwdriver
  • Battery Hydrometer
  • Battery Post Cleaner
  • Battery load tester
  • Chemical to add in the battery (we use China Depot Battery Reconditioning Chemical)

Here are steps to recondition a car battery:

recondition car batteries

Note Electrolyte solution of consists of the mixer of water and sulphuric acid it’s very dangerous to our skins. So be careful when dealing with it.

Step 1: Cleaning Posts.

The very first stage of battery reconditioning would be to clean the battery terminals. There will be corrosion built up on the battery terminals. I would recommend using battery post cleaner for this but it’s optional, you can create your own solution and use other brushes to get the same results.

To create a battery post cleaner, you need 2 tablespoons of baking soda and a tablespoon of water, Mix the two together until you have a runny paste.

Then take an old toothbrush and apply it to your battery terminals. Whilst scrubbing the battery terminals you should notice the solution foaming up. This indicates your solution is reacting to and removing the corrosion from the battery terminals.

If your battery has a heavy corrosion on the terminals you may need switch out your brush for steel wired or steel wool brush. You may also use 300-grain sandpaper.

Now you will need to clean the outside of your battery with a mix of water, baking soda and an old rag. Wipe down the top of the battery around the terminals and caps.

Once you have cleaned the battery and terminals it’s time for you to test the current voltage of the battery and proceed to battery reconditioning.

Step 2: Testing Voltages.

Always utilize a proper voltmeter to check the battery power. Now attach your voltmeter to terminals properly. Make sure that voltmeter is connected correctly.

When you connect voltmeter you will see the current condition. If you see 12.6v+ on voltmeter reading then your battery is in good condition. If you don’t see 12.4v+ or more on voltmeter reading then your battery needs reconditioning.

Note: If the battery shows 0 volts on a voltmeter that your battery has experienced a short circuit and this battery reconditioning process likely won’t repair that.

Once you got battery readings it can tell us whether you need to continue with reconditioning or not. Always keep reading of battery voltages for future recommendations.

Each batteries temperature varies. It depends upon the type of batteries. All Batteries temperature is the most important aspect in overall battery health.

Step 3: Cleaning Cells and Emptying Your Battery.

Now it’s time for you to remove the old acid that’s left inside the battery cells and then clean the inside of the cells. Take your flat head screwdriver and slip it under the battery caps. generally, you’ll find 2 or 3 caps but sometimes you can find 6. When all the caps are removed you need to make sure you have your bucket ready to pull the acid into. You will also need to make sure you have some baking soda close by so if you drop the acid you will neutralize it with the baking soda.

Take the battery and lean it away from yourself into the bucket. Take your time and do not spill any of the battery acids as you move the battery over until it is upside down above the bucket. Once the battery cells are all clean, place your battery to one side and take ½ lb of your baking soda and add it to your bucket of old battery acid. This will neutralize the battery acid so you can safely dispose of it later.

Now it’s time for you to clean the inside of your battery cells. To do this you have to mix a ½ gallon of distilled water with ½lb of baking soda. When mixed utilize your funnel and put the baking soda mixture into every cell of the battery until each cell is full. Snap the battery caps back on and shake your battery around for a good thirty seconds to a minute.

Then remove the battery caps once again and empty your battery cells into the bucket of battery baking soda and acid. You should now have an empty battery that’s clean and ready for battery reconditioning.

Step 4: Reconditioning Your Battery.

we have now an empty clean battery that we can now refill its cells. We will make an electrolyte solution from Epsom salt and distilled water.

Let’s see how electrolyte solution is made?

Take a ½ lb Epsom salt and ½ gallon of distilled water which is common battery reconditioning chemicals. then we should boil the distilled water to make it easier for the Epsom salt to dissolve. Add Epsom salt to distilled water little by little so that all the Epsom salt can get dissolved correctly, and we could see the clear water with dissolved Epsom salt.

Now the electrolyte solution is ready for the battery reconditioning. Fill up the battery cells with new electrolyte. This will boost the voltage and current capability of the battery. All the corrosion and other factors for discharging will get removed and now you have a brand new battery.

Step 5: Car Battery Reconditioning Charger

So now you need to give the reconditioned battery the first charge so get your battery charger and place it as far away from the battery as the leads will allow. Make sure the charger is unplugged while you connect it to prevent any sparks.

Connect the positive lead (+ red cable) to the positive + battery terminal then connect negative (- black cable) to the negative terminal.

Then you need to put it on a slow charge 12v/2amp is the best now leave it to charge not less than 24 hours, 36 hours is ideal.

Once the time has passed it’s time to load test your reconditioned battery. Unplug your battery charger before you decide to disconnect your battery from the charger again this is to prevent any sparks.

Again, take one more voltage reading with your voltmeter and write down the result. If you find more than 12.43v then that’s good and you can move on to a load test.

If you haven’t got above 12.43v yet don’t worry if you had any electrolyte overflow while charging then you have to add the cells with more distilled water and Epsom salt then set the battery on charge for an additional 12 hours. Hopefully, after this time you must be seeing 12v+.

Step 6: Battery Reconditioning Load Test.

Simple process to do a load test of reconditioning is put your 12v car battery back into your car and connect it again.

Do not start the engine simple turn on your high beams this will put your battery under load. With the voltmeter check the reading of the battery,

high beams (do not start the car engine) the high beams will d. Wait 5 minutes to remove any surplus charge. Then take a reading from your voltmeter, if it is reading more than 9.6v then the battery is in good condition. If it’s under 9.6v then the process still needs some work.


Lots of us want to save money by doing things ourselves. We enjoy the independence that self-reliance provides us, and we will handle any DIY project fearlessly, confident that we will learn exactly what we have to as the project unfolds.

I will be the last person to discourage you from becoming self-reliant, however, it is important for you to realize that working with lead acid batteries could be dangerous. It is not within the range of this post to warn you regarding every risk that you might face when you are reconditioning an old battery, so just be sure you understand the risks before continuing.

Lead acid batteries obviously contain acid. Dealing with acid imprudently can lead to disfiguring blindness, burns, and even death. Disposing of it improperly can harm the plumbing systems or the environment.

Automobile batteries also produce hydrogen gas while they are charging, which could explode and ignite fires. And even though direct current might not shock you, there are at least a few mechanics that are missing ring fingers simply because they wedged their wedding rings between positive and negative terminals H.

Unless you have a good working understanding of basic chemistry and electricity, you should not attempt to recondition your own batteries. Working with caustic, explosive, and high energy systems that you don’t understand is a good way to win a Darwin Award. If you’re not familiar with them, all you really need to know is that they’re awarded posthumously, which means after you’re dead. Don’t get one.

battery reconditioning

Leave a Comment