Informational Guide

How To Recondition Batteries Guide

Batteries lose charge over time, and replacing them can be expensive. Learn how to give them new life with our step by step battery reconditioning guide.

It’s fairly common knowledge that batteries have to be replaced eventually. They lose their charge, they become less efficient and in some instances, the case can even bulge and cause major damage to the device or machine that they’re in. However, this is actually only the case for disposable and low-quality batteries. In most cases, it’s actually possible to recondition batteries so that they become one hundred percent functional once again.

It’s a technique called reconditioning and it’s done with a number of different tricks and tips, and we’re going to spill all the beans for you in this article so that you too can learn how to recondition your batteries and get them fully functional again.

First, let’s start with the why; why should we recondition batteries?

battery reconditioning at home

As you may know, batteries can be very expensive to replace.

Be it laptop batteries, car batteries or even non-replaceable batteries that are inside modern phones nowadays, they are incredibly expensive to repair and might not even go down in price as the device ages.

In some cases, old devices won’t even have replacement batteries available because they’re no longer in stock.

Reconditioning batteries allows you to preserve the function of your batteries and even refresh them so that they work the same as they used to, providing you ample charge and saving you a lot of money. It’s also better for the environment because batteries themselves are very hard to recycle and they usually end up in trash bins, leaking chemicals to the environment and causing a huge impact to the well-being of the planet.

Lastly, reconditioning is just convenient. Imagine never having to buy a battery again for a major device because you can personally just recondition it. You’ll save money, you’ll save time and it’s surely going to save you a lot of hassle in the future. There are virtually no disadvantages of reconditioning your batteries outside of putting in a bit of effort, and in this article, you’re going to find that it’s relatively easy to do so.

Are there any dangers When reconditioning batteries?

Batteries can be very dangerous if handled incorrectly, especially if you don’t have the right safety equipment on. It’s vital that you wear glasses and gloves to ensure that the battery acid doesn’t leak out and burn your skin or anything else that it comes in contact with. Batteries can also explode under certain conditions, especially if they are mishandled and treated poorly.

If you start reconditioning a battery but realize that it’s cracked, leaking or damaged, it’s vital that you dispose of the battery as soon as possible. At that point, it’s an unsafe battery and you’re better off disposing it because you can no longer fix it in that state.

Finally, don’t recondition a battery more than three or four times. Reconditioning a battery can be a great way to prolong its life, but as time goes on it will eventually get worn out and you’ll experience diminishing returns each time you recondition it. A reconditioned battery will last several years if you keep working on it, but it will eventually get worse and reconditioning will end up harming the battery more than helping it.

Types of Batteries That Can Be Reconditioned

Lithium-Ion Batteries

These batteries are rechargeable and becoming more popular, yet they are more expensive than the traditional battery types. There are several ways to recondition a lithium-ion battery, including fully discharging it and placing it on the charger or placing the discharged battery in the freezer for 24 hours and then recharging it.

NiCad Rechargeable Batteries

Nickel-based batteries suffer from performance issues, primarily when recharged before they are completely dead. To restore the performance, reconditioning is needed, which requires putting high voltage on the battery terminals.

NiMH Rechargeable Batteries

The Nickel Metal Hydride is another rechargeable battery that is better than the NiCad. To recondition a NiMH rechargeable battery, you need to run deep charge cycles to regain the performance.

Lead Acid Car Batteries

These wet cell batteries don’t require a lot of effort to recondition. You can top off all of the cells with distilled water. Then, it helps to apply a slow charge to the battery.

AGM and Gel Type Batteries

These batteries are safer than the lead-acid variety because nothing spills out if the casing cracks. The best way to recondition the gel battery is to completely discharge it and then recharge it slowly.

How To Recondition A Car Battery

Equipment needed:

  • Protective clothing or apron
  • Goggles, chemical-resistant gloves, and other safety equipment
  • Battery charger
  • Voltmeter
  • Basic tool kit that includes a screwdriver
  • Plastic funnel
  • Two larger plastic buckets
  • Distilled water
  • 1 pound Epsom salt
  • 1 pound baking soda
  • Steel wool
  • Toothbrush
  • Voltmeter
  • Battery load tester (optional)

1. Prepare the Battery

Before you begin, you must clean off the battery terminals, but you must wear gloves to perform this step. You may be dealing with a lot of corrosion that has built up on the posts, which must be cleaned off before reconditioning the battery. Each battery type might have a different size and post configuration, so you want to familiarize yourself with the various components before getting started.

Mix some baking soda with distilled water until it turns into a runny paste. Apply it on the posts and use your steel wool to clean the area. You can also use a toothbrush to scrub the posts if there is corrosion that’s difficult to clean. Don’t be surprised when the mixture foams; this just indicates that it is working. Wash the area down with a little more baking soda and water. Then, wipe it off and allow it to dry completely. 

2. Check the Battery Voltage

Use your voltmeter to check the battery. These aren’t expensive to purchase and are simple to use. Connect the voltmeter to the terminals. If it reads less than 12.6V, then reconditioning might improve the life of your car battery. If the voltmeter reads 0, the battery might have suffered a short circuit and requires replacement.

3. Empty the Battery

If you haven’t put your goggles on yet, now is the time. Make sure they are chemical-resistant, or you could suffer burns from the battery acid. Use your screwdriver to gently get under the battery caps. If you give them a small nudge, they should come off with ease. Make sure your plastic bucket is nearby to pour the acid into.

As you pour the acid into your bucket, make sure the battery is always tilted away from you. Take your time, so there are no spills to deal with. Once you have emptied the battery cells, you can stand it back up as normal. Put half of a pound of baking soda into your bucket to neutralize the old acid.

4. Clean the Cells

Once the cells are empty, you want to mix half a gallon of distilled water with half of a pound of baking soda. Once these are mixed together, use your plastic funnel to pour some into each cell. Once they are full, put the caps on the battery and shake it to clean out the inside. The battery will be heavy, but you should do this for a couple of minutes. Open the caps the same way you did earlier and pour the cleaning fluid into your bucket. Your battery is prepared for reconditioning, and you can safely dispose of the waste liquids.

5. Recondition the Battery

It’s time to refill the battery cells. With distilled water and Epsom salts, you can create your own electrolyte. This raises the voltage and increases the amperage given to your car. It also stops the plate sulfating that kills the battery. To create your mixture, you will combine the Epsom salt with boiling distilled water. The easiest way to do this is to add the boiling distilled water into one clean plastic bucket and then gently add the Epsom salts while you stir.

Once the water is clear, the electrolyte is ready to fill the cells. Use a clean funnel and pour your mixture into each cell. Fill each cell until they are 100% full. If there is some leftover, you can save it for the next time. Put the caps on the battery and shake it again for a couple of minutes. You are ready to charge the battery.

6. Charge the Reconditioned Battery

Take the caps off to ensure the electrolyte solution doesn’t overflow and heat up.

If the battery builds up too much pressure, it can cause a lot of trouble. Place your battery charger as far away as possible from your battery.

Connect the positive lead to your positive battery terminal.

Do the same on the negative side. Slowly charge your battery for a day and a half.

battery reconditioning at home

7. Test the Battery

Use your voltmeter on the battery. If you see 12.43V or more, the battery is ready to be tested. If it hasn’t reached 12.43V yet, continue charging it for another 12 hours. If any of the electrolyte overflowed, make sure you fill it back up.

Remove the battery charger once the voltage reads normal. Place the caps back on and connect the battery to the car. Put your high beams on, but don’t start the car yet. Allow the battery to run under load for a few minutes. Then, use the voltmeter once again to take a reading. You should see 9.6V or more. If it is reading under 9.6V, the battery isn't fully reconditioned, and you should repeat the steps.

You can also cycle the battery. If it fails after the first load test, discharge it completely and recharge it again. To drain the battery, simply put it under load by leaving the high beams on. It might take cycling the battery four to five times before you get the appropriate reading. But, once you do, you have a fully functional battery for a fraction of the cost of a new one.

5 Battery Reconditioning Essentials


FOXWELL BT705 Car Battery Tester 12V 24V,...
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This isn’t just the best diagnostic tool for car battery, but also an advanced unit that offers more than meets the eye. This tester displays information about the starter system, cranking time, and cranking voltage to ensure the health of your car battery.

This option, as the best car battery analyzer/tester also comes highly rated. You can use it on your 12V or 24V battery for maximum versatility. Aside from that, it only takes 2.5 seconds to get the readings you need on the backlit LCD. We recommend this tester for anyone looking to monitor the state of their car battery.

2. INNOVA 3340

Innova 3340 Professional Automotive Digital...
  • Designed to pinpoint engine problems; tests...
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  • Measures up to 15 amps for device testing
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You don't need to be a professional mechanic to get the best automotive multimeter. This option from INNOVA helps you diagnose troubles with the car battery. It will also test wiring, switches, breaker points, solenoids, duty cycle, and alternator diodes for a comprehensive automotive tool.

It comes complete with a temperature probe, carrying case, and inductive RPM clamp. Plus, it features overload protection and auto-shutoff to ensure your safety. With the test lead holders, you also receive the hands-free protection you desire. Look like a professional automotive technician when you whip this device out to check the battery’s condition.

3. EZRED SP101

EZRED SP101 Battery Hydrometer, Factory
  • BATTERY HYDROMETER: This battery tester is...
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You don’t have to spend a lot of money to own the best battery hydrometer. This device allows you to read and understand the battery levels without using temperature tables or float readings. It is made of durable materials that will hold up in stressful environments, such as a professional garage.

It’s also supposed to be one of the more accurate solutions on the market, so you are left guessing about the state of the battery cells. By looking at the reviews, you can see that customers ranging from DIYers to professional technicians have come to rely on this equipment for battery repair and troubleshooting.

4. Associated Equipment US20

Associated Equipment US20 6/12 Volt Value...
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  • 90 minute timer with hold
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  • Safe in any weather

What do you do when your battery won’t crank over anymore? You invest in the best charger for a dead car battery. It provides a charge for both 6 and 12V batteries. Plus, it contains a convenient handle that has a comfortable grip.

The quality steel foot is created for longevity, so you can plan on having this model for many years to come. In total, this charger contains a 90-minute timer plus a hold function. You can safely use it in any weather, allowing you to charge the dead battery when you need it the most. One look at the ratings proves that this company is a leader in the industry.

5. XS Power D6500 XS Series

XS Power D6500 XS Series 12V 3,900 Amp AGM...
  • 12 Volt battery with CA: 1070, Ah: 75
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  • Ultra low internal resistance

When all else fails, you need the best replacement battery for cars. If charging the battery and reconditioning no longer works, replacement is required. While it might cost more than your typical battery, this XS Power model has some special features.

The 12V battery is an Absorbed Glass Mat type, so the electrolyte if suspended in the fiberglass. This sealed and spill-proof battery is resistant to vibration and valve regulated. What you get is an ultra-low internal resistance and a battery that can be mounted in any position safely. Spend a little more now, and you won't need to worry about a replacement for many years to come.

Charging a Dead Car Battery

It’s not difficult to charge a dead car battery. First, locate the battery's positive and negative terminals.

The positive is marked with a "+," while the negative features a "-." Attach your battery charger's red clamp to the positive terminal.

Then, attach the black clamp to the negative terminal. Ensure the connection is tight and move the charger as far away from the battery as possible. 

battery reconditioning at home

Turn on the charger and run it until the battery is operational again. Some devices shut themselves off, and others require that you monitor the gauges. Once the battery is charged, simply remove the clamps in the opposite direction.

Here’s a helpful video if you want to see how to charge your dead battery.

Safety Tips & Precautions When Working with Batteries

There are four main hazards to consider when working with car batteries.

  • Battery acid: 
    This substance is corrosive and will burn your eyes or skin. It can even eat holes through your clothing, which is why you should always wear protective gear when handling car batteries.
  • Flammable gases:
    Car batteries emit hydrogen gas. This gas is flammable and will ignite easily. If it accumulates in a small area, such as a garage, it could cause a fire or explosion.
  • Electrical shock:
    Car batteries can spark, especially when attaching jumper cables
  • Weight:
    Some types of batteries are quite heavy and should be handled with caution.

People Also Ask (FAQs)

How can I diagnose a dead car battery?

There are several signs of a dead car battery. The vehicle might not start, the headlights and radio might not turn on, or you hear nothing when you attempt to turn the key.

What are the reasons why car batteries fail?

50% of premature car battery failure comes from a loss of fluid due to evaporation under high heat, overcharging, or a lack of lithium-ion battery. Undercharging and positive grid growth can also be the culprits. 

When’s the best time to recondition my car battery?

You can recondition the car battery if it seems to be underperforming but still maintains a solid structure.

Is it safe to recondition a car battery at home?

If you take the necessary precautions, you can recondition your car battery at home. Make sure you work in a ventilated area and wear protective gear at all times.

How long does a reconditioned battery last?

While a typical car battery might last five to ten years, you can gain up to 12 years by reconditioning it.

What are some alternatives to the Epsom Salt solution as Battery Electrolyte solution?

If you don't have Epsom salt or simply want an alternative, consider copper sulfate or aluminum sulfate. Both can be mixed with distilled water the same way.

Can you pour vinegar or Gatorade if your battery electrolyte solution is low?

We don’t recommend any other substances inside your car battery. Vinegar is known to form lead acetate inside the battery cell, only causing further problems.

What is the typical reading for a fully charged 12V car battery?

You want to see a reading of 12.6V or higher on the 12V battery.

How can you safely dispose of a car battery?

You want to drop it off at a hazardous waste recycling center or trade it in for a new battery.

Is it alright to overcharge my car battery?

Overcharging a car battery puts excessive wear on the component and could lead to premature failure.

At what voltage reading can you tell that your car battery is flat dead?

The battery is dead when it reads 12V. If it is reading 12.4V, your battery still contains about 50% energy, but you want the battery to read between 12.8 and 12.9V.

Is it alright to use a regular charger for your AGM Battery?

Don’t use a traditional battery charger on recharge it. The AGM charger contains built-in microprocessors that adjust to the requirement of your battery, ensuring it won’t overcharge.


Now you see how simple it is to extend the life of your car battery by reconditioning it. While there are several tools you should invest in to get the job done, we can’t say enough good about FOXWELL BT705.