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How To Recondition Lead Acid Batteries 

 September 19, 2021

By  Phil Borges

A lead-acid battery can be described as a small-sized chemical plant of its own. These batteries store the energy in their plates and are the oldest type of rechargeable batteries.

After they are discharged, the lead matter on the battery’s positive plates reacts with the sulfuric acid in the electrolyte mixture to produce lead sulfate. This turns into crystals when the battery fails. All you need to do is reverse that imbalance in the electrolyte solution. And we’ll tell you how to do that safely at home.

How to recondition lead acid batteries?

Reconditioning lead-acid batteries can easily be reconditioned with a solution of magnesium sulfate and a few other tools found at home. The hardened lead sulfate crystals that are formed on the plates after the battery dies need to be removed so that the battery comes back to 70-80 percent of its original capacity. You can repeat it a few times to lengthen the life of the battery before you replace it.

Lead-acid batteries are typically used in electric cars, golf carts and trucks. The process of degradation of the plates inside the battery happens over time and is known as sulfation. This is typically what kills a battery. However, it can be revived as long as the battery itself is mechanically sound. Let’s see how it is done.

Reconditioning Lead Acid Battery

These batteries have a low energy-to-weight ratio. They also have a low energy-to-volume ratio but they can supply high surge currents. That is why lead-acid batteries are relatively inexpensive and still used in many motor vehicles. They are also widely used in cell phone towers and power back-up supplies in hospitals and places that need stand-alone power. So, it is a great advantage that they can be reconditioned and you know how to recondition a lead acid battery.

Now, there is an easy way to get that job done. But, safety first. Always remember to put on your safety goggles and gloves before you start working with lead-acid batteries. Next, you must make sure that the cells and the plates inside the dead battery are still functional. If they are not, drop the whole project because it means that the battery cannot be reconditioned. But if they are in working condition (even with mild damage), get your tools out.

What you will need the following to recondition lead acid batteries:

  • The damaged battery
  • 7 ounces of Epsom salts like magnesium sulfate
  • 12 ounces of distilled water
  • A battery charger or trickle charger
  • A syringe or a dropper
  • Crocodile clips that are used with PSU
  • Flashlight (this is optional depending on your working circumstances)
  • Paper towels (always come in handy)

Step 1: Remove the battery from the vehicle and place it on your workbench. Now, take off the caps of every battery cell till you gain access to the battery acid.

Step 2: Some batteries have rubber caps and the larger models have screw-in plugs. These can easily be removed using a screwdriver and they are usually not very tight.

Step 3: Open them all and check the level of acid in each of them. Now, you need to balance this solution. For that, you must grab your syringe or dropper and drain each cell of the acid till the capacity is at 50-60 percent.

If some of the cells seem to already have lower levels of acid, add a little solution from the fuller ones that you had to drain out. This is a very strong acid that must be placed in a glass container. So, you must be careful with your hands and clothes during this step.

Step 4: Get rid of the removed battery acid safely. Remember that it has many heavy metals like lead and is highly corrosive.

Step 5: Gather the magnesium sulfate and distilled water and make a saturated solution with the two ingredients. This is done by boiling the distilled water, adding the Epsom salts to it and constantly stirring the salts till the solution reaches its saturation point. This saturation is usually visible to the naked eye.

Step 6: Take the solution and carefully fill each cell with the syringe or dropper. Fill the battery cells to the full level line.

Step 7: Now charge the battery while leaving the caps open. You will notice that a gas will be released during the process. That’s why it is important to leave the caps open.

Step 8: Now connect the battery charger to the terminals of the battery and wait till you finish the charging cycle. You might have to do this all night long with a trickle charger in case your battery is extremely drained or perhaps even a little damaged. This is to help the low amperage of the battery you are trying to recondition. This amperage is easy to calculate.

Step 9: If you don’t have a battery charger, you must close the cells with the covers and place them back in the vehicle. Using the alternator in the vehicle, jump-start the battery for about an hour or two till the battery is charged.

If the process is a success, you will have a fully reconditioned battery that is likely to last another six months to a year. You can do this three to five times till the procedure no longer works.

Ideally, you must let the process run for a few days so that the plates are properly cleaned. After this, you must drain the magnesium sulfate solution from the battery and replace it with a 35-65 acid and water solution which is the recommended measure. However, before you remove the Epsom salts solution and fill it with the acid solution, make sure the battery is completely discharged.

Can Sealed Lead Acid Batteries Be Reconditioned

Now, if you have done this in the past, you must have noticed that some batteries come with a seal that is screwed on top of the cells. Some others come with a sealing strip. Both are clearly visible. In case you are dealing with one of these models, you must remove the seal by cutting the edges of the sealing strip. This way, you manage to loosen it if not remove it entirely although most are completely removable.

If the seal seems to be glued into place, you must locate the edge of the strip carefully and pry it open using a flat screwdriver. As mentioned before, you can also try to cut it open by using a craft knife that is nicely sharpened or crocodile clips if you are crafty with your hands.

It is important to note here that if the battery has been discharged for too long because of sulfation, they lose the capacity to accept a charge. This is a process where active materials on the battery plates like lead and lead dioxide react with the sulfuric acid and form lead sulfate.

This is usually formed in an amorphous state and can be reversed into its original form of sulfuric acid, lead dioxide and lead. As time passes and the battery goes through multiple discharges, it goes from an amorphous form to a crystalline form which cannot be dissolved using the above technique. Sulfation happens when the battery does not get enough charging while it is being operated upon.

Frequently Asked Questions

How Do Lead Acid Batteries Work?

A lead-acid battery has one positive and one negative plate. There is a separator and an electrolyte, all of which are in a plastic container. Every battery has multiple cells that are lined up in a series to give the battery the necessary voltage. Once the battery is charged, it provides power to the external circuits and helps operate the vehicle.

How to Charge a Lead Acid Battery?

The charge current must be selected according to the size of the battery. If you are charging a 12-volt battery with six cells to a limit of 2.4 volts, the voltage must be 14.40 volts which is six times 2.4 volts. This is about 10-30 percent of the rated capacity.

How Long Do Lead Acid Batteries Last

Sealed models can last anywhere from 3 to 5 years but can also last for more than 12 years depending on how it was manufactured.

We hope that this article has given you a lot of ideas on how to recondition lead acid battery that you can use for your future projects. 

About the author

Hi, I'm Phil Borges.. thanks for reading.. My wife says I can't shut up about batteries so to save my marriage I've started this blog .. where I'd be ranting about batteries! Please leave a comment if you have any questions, I'm happy to help!

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