How to Recondition Car Batteries – Fred’s Auto Removal

Recondition car batteries

It Starts with Your Battery

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Dead or weak car batteries can be more than just annoying.  Being stranded by a dead battery in the wrong part of town can be be downright dangerous.  So learning to recondition car batteries can be a useful skill.

But just because your old battery is growing weaker doesn’t necessarily mean you need to replace it or

sell your junk car

to us you could just fix it your self.  Many older batteries still have plenty of life left in them, if you know how to find it.

Restoring an old battery

can be a much better solution than buying a new one.

Why Lead Acid Batteries Weaken

Car batteries rely on lead electrodes suspended in a strong solution of  acid to produce a electrical charge.  This formula has been used to make batteries for over 150 years.

Lead acid batteries rely on concentrated sulfuric acid to provide the positive charge that produces the flow of electrons that powers our automobile electrical systems. Lead and lead oxide plates provide the electrons that are pulled through the positive and negative terminals on the battery.

The fact that the flow is reversible is the key to the success of battery design, because by adding electricity back into the battery, we can restore its charge.  And since the acid and the lead plates are relatively content to sit quietly during periods when there is neither a change nor a discharge, lead acid batteries store their power for a long time, as much as two years or more with no activity.

When your battery won’t fully recharge, the likely culprit is an accumulation of sulfate on the lead electrodes which forms a shield that keeps the electrons from flowing between the electrodes.  Sulfate is a compound of sulfur and oxygen, and forms from the sulfur in the acid.

Sulfate coatings on lead electrodes has the effect of reducing the concentration of hydrogen ions in the acid solution, which also reduces he amount of lead that can react with the hydrogen ions to produce the flow of electrons.  This process is called sulfation, and will eventually weaken all lead acid batteries to the point that they can no longer produce enough power to start an engine.

The good news is that the process is often reversible, meaning that a lead acid battery that was otherwise useless can be restored to it’s former strength.

Reconditioning Car Batteries

Desulfating a Dead Battery

Since sulfating causes batteries to weaken, you won’t be surprised to learn that desulfating is the key to restoring them.  It’s a process you can do at home, although it’s not without a few risks.  Be sure to read the disclaimer at the end of this article before you decide to tackle it.  You’ll need proper protective gear, including safety glasses.

You will need a few items in order to desulfate a battery:

  1. Battery post cleaner.

  2. Battery load tester

    and/or a multimeter.
  3. Battery charger or better yet a

    desulfating battery charger

  4. Funnel.
  5. Epsom salts.
  6. Distilled water.

Step 1.

Begin by inspecting the battery.  If the case is swollen or cracked, or the terminals are loose or wobbly, the battery can’t be reconditioned.  Use extra caution when you remove it, because it may leak acid that will damage your clothes, skin, and just about every other surface that it touches.  Recycle it by exchanging it with the store from which you purchase your replacement battery.

Step 2.

If the battery is does not appear to have damage, disconnect the cables from the battery terminals, and use the post cleaner to thoroughly clean both the positive and negative battery terminals.

Step 3.

Once the terminals are clean, remove the caps from the cells, and check the fluid levels.  If they’re low, add distilled water to each cell that needs it.  Don’t use tap water.  Now, use the charger to recharge the battery.  The charger’s instructions will tell you how long to leave it connected.  Remember that the battery will be producing explosive gases during charging, so eliminate all sources of spark or flame, and make sure that the charger is off or unplugged when connecting or disconnecting it to or from the battery terminals since it may spark if it’s on.

Step 4.

Connect the positive (red) cable from the multimeter or the load tester to the positive terminal on the battery, and the negative (black) cable to the negative terminal on the battery.  If you’re using a load tester, make sure it’s not in load testing mode.  If the voltage is greater than 12.0 volts, you should be able to recondition the battery.  If it’s below 12.0 volts, the battery likely has a bad cell and you may not be able to recondition the battery.

Step 5.

You can skip this step if you don’t have a load tester.  If you do, switch it to load test mode, and follow the meter’s instructions to test the battery under a load.  If you find that the the voltage under a load is 6.1 volts or less, you probably won’t be able to recondition the battery.  This is a more accurate test than the multimeter by itself.

Step 6.

Use your desulfating charger to apply an equalizing charge to the battery.   Follow the charger’s instructions, and then retest the battery either with the load tester, as you did in step 5, or with the multimeter.  If the voltage has not risen from the original test, go to step 7.  If you don’t have a desulfating charger, you can skip step 6 and go right to step 7.

Step 7.

Heat 1/2 quart of water to 150 degrees, and dissolve 8 ounces epsom salts in the water.  Remove a 1/2 quart of fluid from the battery, making sure that you remove an equal volume from each cell.  This can be done with a baster or battery hydrometer.  Replace the fluid with the dissolved epsom salts, again being careful to place equal volumes in each cell.  Charge the battery again, and repeat either the load or multimeter test.  If the voltage is above 12.3 volts, you’re battery is now likely reconditioned and should give you several more months or years of service.  If it’s less than 12.3 volts, you should replace the battery.

Batteries that can’t be reconditioned must be recycled by qualified recyclers since they contain hazardous substances.  Because it’s always better to reuse than to recycle, by reconditioning your old car batteries, you’re helping to reduce waste and environmental damage.

Hopefully, you’ll save some money at the same time.


Lots of us love to save money by doing things ourselves.  We treasure the independence that self-reliance gives us, and we will tackle any DIY project fearlessly, confident that we’ll learn what we need to as the project unfolds.

I’ll be the last person to discourage you from being self-reliant, but It’s important for you to understand that

working with lead acid batteries can be dangerous

.  It is not within the scope of this article to warn you about every risk that you might face when you’re reconditioning an old battery, so make sure that you understand the risks before proceeding.

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

Automobile batteries also produce hydrogen gas when they’re charging, which can explode and ignite fires.  And even though direct current may not shock you, there are at least a few mechanics that are missing ring fingers because they wedged their wedding rings between positive and negative terminalsH.

Unless you have a good working knowledge 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.

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