How to recondition a car battery

Simple, step-by-step guide on how to recondition your car battery from home.

How to recondition a car battery?

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We’ve all done it: taken an old, dead battery, thrown it straight into the trash, and fired up a shopping website or driven to the store to get an expensive new one to replace it. Feels like the easiest thing to do, right? If you’ve stumbled across this guide, chances are you might be in a position where you need a pricey new battery, but you know there might be another option.

Well, you’ve come to the right place! Reconditioning your dead car batteries to bring them back to life is so much cheaper, easier, and more satisfying than you might think.

Watch Now: This simple method brings back dead car batteries

When it comes to car batteries specifically, reconditioning your old ones can be a breeze, and in the long run, could save you huge amounts of money. In this step-by-step guide, we’ll show you why reconditioning your old car batteries is a great move, and how to do it easily and quickly.

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What is battery reconditioning?

Simply put, how to recondition a car battery describes to process of bringing your dead batteries back to life, to restore the former energy-giving capacities of a battery that you thought was long gone. It can feel daunting to do this, especially with a car battery – but with this walkthrough and the right tools at your disposal, we’ll show you how easy it is, and how it can be a process you can do again and again.

Photo by NeONBRAND on Unsplash

Why should I recondition your old car batteries?


The average car battery needs replacing after around three years. After four or five years, it becomes completely unusable, and many batteries will reach the end of their usability way before that. By learning how to recondition your car batteries, you can extend their lifespan by up to two years, meaning that your batteries last longer without you having to buy a new one.


Learning how to recondition a battery will not only increase the time you can use it but will also, of course, save you money. The average car battery can price in the region of $80-$100 (and even more, in many cases), and so by the time you’ve invested a small amount in learning how to recondition batteries and acquiring the tools you’ll need – which you’ll most likely already have sitting around the house – you’ll have saved money!

The added benefit here, too, is that once you learn how to do it with a car battery, you can apply the process to all different types of household battery, and you’ll pretty much never have to buy a new battery again – so you could end up saving hundreds of dollars a year, and up to thousands in the long run.

Car batteries, laptop batteries, motorcycle batteries, batteries for solar panel systems, golf cart batteries, and AA, AAA, and 12V batteries used for all your household appliances – the list is almost endless. It can even become a lucrative side hustle!


The other, potentially more important thing to consider is the impact you have on the environment by throwing away your old batteries. As most car batteries are lead-acid batteries, throwing them away can be harmful, specifically due to the lead element within. Once the poisonous lead component enters into groundwater or soil, it can very quickly make its way into our food cycle, through grazing animals or vegetation.

While lead-acid batteries are 99% recyclable, reconditioning them to make them re-usable in the long run is a much more friendly option, and doesn’t require the hassle of recycling them safely.

How to recondition your car battery at home?

As we’ve seen so far, the benefits and process of how reconditioning your car battery instead of buying a new one are massive. So without further ado, let’s learn how to do it at home!

A word on safety

A lot of people may find the prospect of working with a car battery daunting, and the first thing that might come to mind is safety. So, is it safe to recondition your battery at home? Of course it is!

However, it’s very important to note that, like all batteries, car batteries can be hazardous if not handled correctly. Car batteries contain acid and lead, and incorrect handling of the battery can cause leakage of these materials onto skin or other surfaces. Wearing protective equipment is of paramount importance while you perform the reconditioning.

Likewise, if the battery you’re reconditioning is damaged or cracked, safely dispose of it instead of attempting to recondition it, as it would be unsafe to attempt to bring it back to life and could cause harm.

Ensure to read this guide through fully before beginning the process: some parts of the reconditioning require careful handling of some dangerous materials, particularly the acid in the battery – so browse through to make sure you know what’s coming up!

Finally, make sure you perform the reconditioning in a well-ventilated room or area.


To recondition your car battery, you’ll need the following:

  • Personal protective equipment: a mask, goggles, disposable rubber gloves, and a protective apron. Ensure that the goggles in particular are chemical-resistant.
  • Battery charger
  • Voltmeter
  • Toothbrush
  • Plastic funnel
  • Flathead screwdriver
  • Two plastic buckets
  • 1 gallon distilled water
  • 1 pound Epsom salt
  • 1 pound baking soda
  • Steel wool
  • Two plastic stirrers
  • One plastic jug
  • One plastic container
  • Battery load tester

How to recondition your car battery in 8 Simple Steps

Step 1: Before we begin with the reconditioning, put on your mask, goggles, rubber gloves, and apron.

Step 2: Corrosion needs to be cleaned off thoroughly before performing any reconditioning, and there may be some build-up here. Take two parts baking soda to one past water, and prepare a paste for which to clean the battery in your plastic container. Apply it to any corrosion using the toothbrush, and then use the toothbrush or (if it’s built-up) the steel wool to scrub it off. If the mixture foams, that just means it’s doing the job, so don’t worry!

Once you’ve cleaned off all the corrosion, wipe the battery down and leave to dry completely.

Step 3: Using your voltmeter, measure the volt reading of the battery. Make sure you connect the voltmeter to the battery terminals correctly. If the volt reading is 12.6V or higher, you still have some life in the battery. If it’s less than that, you’re good to go with the reconditioning!

Note: if the volt reading is 0, the battery will probably need replacing, as it likely will have suffered a short circuit.

Step 4: Use the flat-head screwdriver to carefully remove the battery caps, and place them to one side in a safe place. Then, making sure the battery is tilting away from you, pour the acid into the bucket. Take it slow at this point: you’re in no rush!

Once done, add at least half a pound of baking soda to the acid in the bucket to neutralize it.

Step 5: Prepare another solution of baking soda and water – this one should be slightly thinner (around half a gallon of water to half a pound of baking soda would work). Mix it well in your plastic jug using the stirrer, and then using your plastic funnel, pour it into each battery cell. Clean off your plastic funnel and stirrer thoroughly – you’ll need them for the next step.

Once each cell is full, replace the battery caps on them, and shake gently for at least a minute. Remove the battery caps using the flathead screwdriver as before and place them to one side, and empty the baking soda solution into the bucket with the now-neutralized battery acid. The contents of this bucket are now ready to be disposed of safely.

Congratulations! Your battery is now ready for reconditioning.

Step 6: The next step is to refill the battery cells to restore it to its former charging glory. To do this, we create a new electrolyte solution, which will increase the voltage of the battery. Take the second clean bucket, and combine one liter of the distilled water with 120 grams of Epsom salt. Mix it well using the plastic stirrer. Once the solution is clear, it’s ready to use.

Take the clean funnel and carefully pour the Epsom solution into each cell until they’re full. Replace the battery caps and shake the battery again for at least a minute. If you have any leftover Epsom solution, you can store it and use it for your next reconditioning.

Step 7: Now the battery’s ready to charge! This takes time, so have patience – your battery will be ready to re-use in no time.

Remove the battery caps to ensure that there’s no overflow as the battery charges. Place the battery charger a good distance away from your car battery, and connect the positive leads to the positive terminal of the battery, and vice versa on the negative side. Leave to charge for between 24 to 36 hours – nearer the 36-hour mark is better.

Step 8: Check the voltage of your battery with the voltmeter. If the voltage is 12.43V or above, it’s ready for a load test. If it’s lower than that, continue to charge it for another half a day. If any of the electrolyte solution has overflowed during the charging process, it will need to be refilled.

When the voltage is 12.43V or above, remove from the battery charger and replace the caps. Use the battery load tester to test it. If it maintains 9.6V for more than 15 seconds, the battery is successfully reconditioned and ready to use!

Alternatively, you can do this to test it: connect the battery to the car, put your high beams on (without starting the car) and let it run for a few minutes. Once you’ve done that, remove your battery and check it with the voltmeter.

If it’s reading at 9.6V or more, the battery’s good to go; if it’s reading under that, unfortunately it hasn’t reconditioned successfully, and you may need to repeat the process from the beginning.

You're done!

Once you have the correct reading on the battery, congratulations – you’ve just reconditioned your first car battery, and you now basically have a brand-new battery for a smidgen of the cost of buying a new one!

Frequently asked questions

If I can’t find Epsom salt, what can I use for the electrolyte solution?

If Epsom salt isn’t readily available in your area, don’t worry: there are two other chemicals that you can mix with distilled water for the electrolyte solution. Either copper sulfate or aluminum sulfate can easily be used to replace the Epsom salt; for the aluminum sulfate, create a ratio of 1:1 with the distilled water.

Can I use any other solution in place of the electrolyte solution, like vinegar or Gatorade?

I would strongly advise you don’t! Vinegar can cause a build-up of lead acetate inside the cell, which will just cause more issues; and your Gatorade is better off for drinking while you recondition the battery with the Epsom salt solution!

How do I know when my battery is fully charged?

If your voltage reading for the battery is 12.6V or higher, you’ve got a fully-charged battery. Ideally, you want the battery to read at 12.8 or 12.9V at rest.

What if I overcharge my battery?

Overcharging your battery can cause unnecessary damage, and may mean it fails before its natural lifespan. When charging the battery in Step 7, make sure to stick to the recommended time of 24 to 36 hours, and check it towards the end of this period.

How long will my reconditioned battery last?

A reconditioned battery can add years onto a battery’s usability: you can achieve up to 12 years of use by reconditioning your car battery, instead of their normal life of four to five years.

Voltmeters, battery chargers, load testers… where do I get these?

All of these things can be found at any good hardware store or online (along with everything else you’ll need), and the well-known models these days are easy to use and have very clear instructions, so you shouldn’t have any trouble getting to grips with them.

I know that these things can sound intimidating, but trust me – once you’ve used them once, you’ll get the hang of them!

But… is it really safe?

Of course! By taking all the necessary precautions and working in a ventilated area, reconditioning your car battery is safe, easy, and fun to do!


As this guide has shown, reconditioning your old car battery is not only a breeze but has huge advantages and can save you a huge amount of money – and even make you some – in the long run.

If you’d like to learn more about it, hear here for more invaluable information and resources on how to turn throwing away old car batteries into a thing of the past!

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