How to Recondition Deep Cycle Batteries at Home

Like any other electrical component, batteries experience wear and tear. However, before they completely die, they can go into sleep or recovery mode. Here are some simple steps to recondition an AGM battery at home:

First, drain the battery acid from the deep cycle battery. Heat distilled water and add Epsom salt to it. Fill the battery cells with this solution. Charge the battery for 24 hours with the caps off and check the readings. A deep cycle battery can be reconditioned using distilled water, baking soda, and Epsom salts at home.

Deep Cycle Battery Voltage Chart

State of Charge Voltage Voltage Voltage
100% 12.70 12.73 12.75
75% 12.50 12.53 12.55
50% 12.24 12.28 12.31
25% 11.90 11.96 12.00
0% 11.80 11.85 11.89

Deep cycle batteries, also known as lead-acid batteries, typically die earlier than expected, especially when used continuously. Therefore, reconditioning them once a year ensures that they run efficiently. Here’s how to recondition a deep cycle battery:

How to restore a deep cycle battery?

Are you wondering how to restore your dead deep cycle battery? You can use some household products and tools to recondition it. Before getting started, ensure that you have all the necessary items. Here’s a checklist for you:

  • 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 To Recondition Batteries At Home?

Reconditioning batteries is a great way to get them working like new again. It involves removing any dirt or other substances that may be interfering with its operation, then running it through an electrical cycle to clean out any residual material that didn’t get removed during manufacture.

The process can be repeated until the battery reaches its full capacity once again. This is especially useful if you have old car batteries lying around that aren’t being used anymore. You’ll always want to wear safety goggles when performing this procedure though, for safety reasons.

How To Recondition Lead Acid Battery?

You can recondition lead acid batteries by first fully charging the battery, then slowly discharging it over a period of several hours. Be sure to discharge the battery all the way to zero volts (or as close as possible) then recharge it again. Repeat this process several times.

This reconditioning process will cleanse the lead sulfate deposits from the plates and return the battery to its original condition.

How To Recondition Dead Batteries?

A dead battery can be reconditioned by using a battery charger to bring it back to life. Once it is fully charged, remove the battery from the charger and let it sit for about 5 minutes. Then, reattach the battery to the charger and let it charge for an additional hour. This should be enough to bring your dead battery back to life.

How To Recondition Old Batteries

There are a few ways on reconditioning a battery that is old using the battery reconditioning method. One is to use a battery desulfator. A battery desulfator uses pulsed current to remove the sulfur from the battery plates, which restores the battery to its original condition. You can also try using a battery rejuvenator, which is a device that sends a high-frequency AC signal through the battery. This signal breaks down the crystalline structure of the lead sulfate deposits on the battery plates, which restores lost capacity and allows for more charging and discharging cycles. Finally, you can try using a Battery Rejuvenation Technique, which involves boiling Epsom salt (magnesium sulfate) in water and then pouring it over the corroded areas of the battery. This technique dissolves the lead sulfate deposits, which restores battery function.

No matter what method you choose, it’s important to be patient and let the battery fully charge and discharge a few times before using it again. It may also take a while for the battery to reach its full capacity. So, if you need a working battery immediately, it might be best to buy a new one. But if you’re willing to wait, reconditioning an old battery can save you some money in the long run. Just be sure to follow the instructions carefully and take your time so that you don’t damage the battery further.

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 to Charge a Dead Deep Cycle 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.

How To Bring A Deep Cycle Battery Back To Life?

If your deep cycle battery is dead, there’s no need to despair – you can bring it back to life with a little bit of effort. Here’s what you’ll need to do:

  1. Clean the terminals and posts. This will help ensure that electricity can flow freely into and out of the battery.
  2. Charge the battery using a trickle charger or a solar charger. Be sure to follow the instructions that come with your charger carefully.
  3. Once the battery is charged, test it by attaching it to an inverter and seeing if it powers on. If not, try charging it again – sometimes batteries just need a little extra oomph to get going again.

If you put in a little bit of work, you can usually revive a dead deep cycle battery. Just be sure to take care of it properly afterwards so that it doesn’t die again!

Can deep cycle gel batteries be reconditioned?

Yes, deep cycle gel batteries can be reconditioned! In fact, this is a great way to extend the life of your battery and get more bang for your buck. Here’s how you do it:

  1. Disconnect the battery from all electronics and remove the caps on the top.
  2. Pour distilled water into each cell until it’s about two-thirds full. (Make sure you don’t go over this or you’ll risk spilling acid on yourself.)
  3. Put the caps back on and shake the battery up and down for a few minutes to mix the water with the acid.
  4. Let it sit for 24 hours so that the water can soak in.
  5. After 24 hours, reconnect the battery to your electronics and see if it’s holding a charge.


It is important to discharge a gel battery as much as possible and then charge it very slowly in order for the cells inside of your device. This will help remove any sulfation that has built up on the plates. Once the battery is discharged, you can then use a reconditioning charger to bring the battery back to life.

If you don’t have access to a reconditioning charger, you can try using a low-voltage power supply or even a solar panel. Just be sure not to exceed the voltage rating of the battery, or you could damage it permanently.

Battery maintenance is an important aspect of owning a deep cycle battery, and reconditioning is just one part of it. Regular cleaning and checking the electrolyte levels are also important tasks to keep your battery running smoothly.

About the author, Phil Borges

Phil Borges is a battery aficionado. He's written extensively about batteries, and he loves nothing more than discussing the latest innovations in the industry. He has a deep understanding of how batteries work, and he's always on the lookout for new ways to improve their performance.