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How to Recondition Deep Cycle Batteries at Home 

 September 19, 2021

By  Phil Borges

Batteries, like any other electrical component, experience wear and tear. But before they die, sometimes they go into sleep or recovery mode. Here are a few simple steps on how to recondition a car battery at home. Let’s see how that is done.

A deep cycle battery can be reconditioned using distilled water, baking soda and Epsom salts at home. Start by draining the battery acid. Then, heat some distilled water and add the Epsom salt to it. Fill the battery cells with this solution. Charge the dead battery for 24 hours with the caps off and check the readings.

Deep cycle batteries, also called lead-acid batteries, are likely to die before you expect them to, usually because they have been used continuously. Typically, you must recondition them once a year to make sure they run efficiently. Here’s how.

Can You Recondition A Deep Cycle Battery?

Deep cycle battery reconditioning is indeed doable. And it is quite easy to do that too. These batteries are usually used in recreational vehicles like campers and boats because they are required to be powered only for a short period of time. They come in variants of 6 and 12 volts. So, check the voltage of the battery you want to recondition. Now, let’s get started.

How Do You Restore a Deep Cycle Battery?

To recondition deep cycle battery, you will need a few tools and some household products. Make sure you have them all before you get started. Here’s the checklist.

  • Safety goggles 
  • Safety gloves
  • Distilled water
  • Epsom salt
  • Baking soda
  • A flat screwdriver
  • A funnel
  • Battery charger
  • The dead battery itself

Step 1: Using a load tester, get a reading on the charge on your dead battery. This device is used to measure the amperes produced by the battery. The result will be poor but it will give you a sense of the current state of your battery.

A good battery must produce a high charge so that the engine of your vehicle (say an RV) can get started. This is described as CCA or cold cranking amps. If the dial of the load tester is in the green area marked as ‘OK’, you are good to go. If it is in the red zone, you need to recondition it.

Step 2: Clean the terminals and the surface of the battery with a tissue or a dry cloth to remove any dirt or debris on it. If you are dealing with an old battery, you are likely to see some corrosion in the form of a white powder on the surface.

Before you start the process of reconditioning, make sure you wear safety gloves and goggles. For the purpose of cleaning, you can also make a quick cleaning agent by mixing water and baking powder.

Step 3: Twist the caps of the battery to loosen them. Depending on the model, you might have to use a flat screwdriver to get the job done.

Step 4: You will see acid inside the battery which must be removed. Make sure you don’t get any of it on your skin or clothes as it will burn because, you know, it is acid.

Step 5: Dispose of the acid safely.

Step 6: Mix baking soda with the distilled water. For every gallon of water, you must add 10 ounces of baking soda. Ideally, you must do this in small portions while making sure that the baking soda is being dissolved. This is a strong cleaning agent and is known to be of great help in all kinds of cleaning processes. Using this mixture you will clean the insides of the battery.

Step 7: Slowly pour the baking soda and water solution into all the cells of the battery using a funnel. Once the cells are filled, put back the battery caps and shake it for approximately 30 seconds. Remove the caps of the battery and get rid of the solution.

Step 8: Now, add Epsom salt to distilled water. For this step, you must heat the distilled water so that the salt dissolves easily. For every gallon of water, you must add 15 ounces of Epsom salt. This solution must also be prepared in small amounts like the baking soda and water solution.

Step 9: Pour the solution into all the cells of the battery.

Step 10: Now, using a battery charger, charge your dead battery for the next 24 hours without putting the caps back on. This is because sometimes the liquid might overflow while it is charging because of the heat it produces.

Step 11: After the said 24 hours, take another reading of your battery. If the process worked, you will see an increase in the power of the battery.

If you want to take it up a notch, you can charge the battery for another 24 hours by placing the charger in trickle mode. You are likely to see the Epsom salt and water solution overflowing again.

In that case, disconnect the battery from the charger, wipe the cells clean and refill them with the solution as needed. Don’t forget to put your safety gear back on. Take another stab at the reading and you should see better values. You should also take the battery to the load tester and check the amperes.

Step 12: Now drain the battery until it gets to a 10-volt reading and charge it to the maximum if you want to increase the CCA. This process is called cycling the battery.

Step 13: Even when the battery is at 100 percent, it is not uncommon to see some of the solution overflow. With your safety gear on, wipe off the excess liquid on the surface and check the amperes and voltage.

Refurbished deep cycle batteries can restored back their original performance and usefulness.

Frequently Asked Questions

How Do I Know If My Deep Cycle Battery Is Bad?

You know a battery is dead when it has a damaged cell. You will know that’s the case if the voltage is fine when the battery is fully charged but when it is using power, it drops drastically.

These are hard to repair which means you will need to get new batteries. If the charge of a deep cycle battery is less than 10 volts, it is tough to recondition it. This happens when the battery has been left in storage for too long.

How Do You Recharge a Deeply Drained Battery?

Most modern lead acid batteries have a 12-volt charge. If the battery is not overly sulfated, there are a few ways to bring it back to life. Sulfation is when the plates of the battery develop sulfated oxide on the surface because they have not been used for too long.

If this is the case, it will take anywhere from three to 20 cycles to be revived. Even then, they will not reach their original 100 percent capacity. Otherwise, you can connect a battery of the same capacity to the dead battery and revive it.

Turn the low voltage switch off and connect the negative terminal of the good battery to the negative of the dead battery using jumper cables. Connect the dead battery to a charger and switch it on.

Keep an eye on the dead battery’s voltage using a voltmeter till it reaches 11.5 volts. Remove the good battery and keep charging the dead battery to the maximum. Make sure the battery does not overheat and that the voltmeter reading doesn’t go higher than 15 volts. Disconnect the charger and leave the battery for about four hours. Check the readings again to see if it is 12.8 volts.

How Long Will a Reconditioned Deep Cycle Battery Last?

This depends on usage but a new one is meant to last anywhere for two to eight years. A reconditioned deep cycle battery used in a car can go on for another year. And you can do this two or three times under normal circumstances. But all of this depends on the type of battery you are reconditioning, how many times you have reconditioned it and what you are using the battery for.

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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