Reconditioning Boat Batteries: A Step-By-Step Guide

Marine batteries are often replaced, but they can be reconditioned. This involves jumpstarting the reverse reaction or cleaning out the unreactive material. Before attempting to recondition a battery, it is important to check for any damage, such as cracks, and to ensure you are wearing protective clothing. The process involves cleaning the battery terminals, testing the voltage, and recharging the battery. In some cases, it may be necessary to empty and clean the battery cells, and refill them with a new solution. This can be done using a variety of methods and solutions, including distilled water, Epsom salts, and baking soda.

Cleaning the battery

Corrosion is the most common problem with older batteries. You will notice a white powder appearing on the exterior of the battery, which is toxic. It is important to wash this off before proceeding with any other steps. Be sure to wear gloves and safety goggles to protect yourself from the toxic substances.

To clean the battery, prepare a mixture of one gallon of water and one pound of baking soda. The baking soda neutralises the acid from the battery. Check if your battery is greasy or dirty, and if so, add dish soap to the water and baking soda mixture.

Next, remove the battery terminals using two wrenches, ensuring they are the right size. Once removed, use the solution to clean the clamps and terminals thoroughly using a toothbrush.

After this process, wipe the battery dry and check for any damage or cracks. If the battery is mechanically sound, place petroleum jelly onto the terminals. You can also use a commercial protection spray on them before reattaching the clamps.

If your battery is a sealed battery, you will need to drill through the 'shadow plugs' that cover the openings to the battery cells.

Additional Tips

• If you see white powder crystals forming on the battery terminals, clean these off before you start reconditioning.
• Use a baking soda solution to clean the battery terminals.
• If the battery is too dirty, a foaming reaction means the solution is working.
• You can use steel wool for heavily corroded batteries.
• Before reattaching the terminals, apply a small amount of petroleum jelly to them.
• After cleaning, always wipe the battery dry and check for any damage or cracks.
• If the battery is not in good physical shape, it is best to purchase a new one.
• Do not use tap water as it contains minerals that can cause corrosion.
• Be careful not to overfill the battery cells as the water spilling out will contain acid.

Removing the cell covers

Before beginning, ensure you have the necessary tools and safety equipment. You will need a screwdriver or needle-nose pliers to remove the cell covers. It is also important to wear safety glasses to protect your eyes from the battery acid, which can be extremely harmful. Additionally, make sure to work in a well-ventilated area to avoid inhaling any toxic fumes. Have a rag or cloth ready to wipe away any spills or mess.

Locate the cell covers on your battery. They are usually found on the top of the battery and may be secured in different ways depending on the battery type. Some batteries have screw-on cell covers, while others may have snap-on or plug-in covers. Identify the type of cell covers your battery has and choose the appropriate tool for removal.

Using your chosen tool, carefully begin to remove the cell covers. If you are using a screwdriver, insert it into the slot or groove on the cover and gently pry it open. If you are using needle-nose pliers, grip the cover firmly but carefully to avoid damaging the battery. Be cautious not to drop or damage the cell covers, as they may be reused later. Place them aside in a safe place where they won't be accidentally knocked over.

As you remove the cell covers, pay close attention to keeping the battery cells clean and free from debris or dirt. Any foreign objects that fall into the cells can cause damage or create a short circuit. Use the rag or cloth to wipe away any dust or residue that may accumulate during the removal process. Ensure that no liquid spills out of the cells, as it may contain acid that can be harmful to your skin and clothing.

Once all the cell covers have been removed, inspect the battery cells for any signs of damage or corrosion. Look for any cracks, leaks, or discolouration that could indicate a problem with the battery. If you notice any severe damage, it may be advisable to discontinue the reconditioning process and consult a professional or dispose of the battery properly.

After completing the inspection and ensuring the battery cells are in good condition, you can proceed to the next step in the reconditioning process, such as cleaning or refilling the cells. Remember to work carefully and follow all safety precautions to ensure a successful and safe reconditioning of your boat battery.

Filling the battery cells with water

Once the cell covers are removed, the next step is to fill each cell completely with distilled water. This is a critical safety precaution, as oxygen and hydrogen left in the cell can cause the battery to spark or explode. It is also important to avoid overfilling the cells, as the water spilling out will contain acid. The amount of water added will depend on the battery size and the levels of acid in it. A funnel may be useful to ensure the water is directed into the cells without spilling.

After filling the cells, it is important to clean up any spills or mess using a rag or sponge. It is also important to dispose of any acidic waste properly, such as by taking it to a recycling centre or other hazardous waste facility.

At this stage, the battery may be expected to work, and it is worth trying to charge it with a conventional charger. If this does not work, the next step is to connect the battery to a battery rejuvenator, which can break apart the sulfate buildup so that the battery can be charged again.

It is important to note that reconditioning a battery can be dangerous, and it is crucial to take appropriate safety precautions, including wearing protective gear and working in a well-ventilated area.

Connecting the battery to a battery rejuvenator

Once you have filled the cells with water, you can expect the battery to start working immediately. Try charging it with a conventional charger for batteries. If it does charge, continue charging it. If it doesn't, you may need a battery rejuvenator.

A battery rejuvenator can pulsate energy through the plates of the battery, causing the sulfate buildup to break apart. This will allow the battery to be charged again.

To connect the battery to a battery rejuvenator, you will need to set your multimeter to 10A and connect it in series with the charger and the battery. When you connect it to the battery, it should draw 100-200mA, which is a sign of a dead battery. Set your PSU to 14V or connect your charger and let it sit for a day or two. After this, your battery should draw 500-1000mA.

The amount of time you will need to charge your battery can be calculated using the following formula:

Ah capacity = Amps that your battery is drawing x hours

For example, if your battery is drawing 0.39A and you want to charge it for 20.5 hours, the Ah capacity would be 8Ah.

Testing the voltage

Charging the Battery:

Start by fully charging your battery using a conventional charger. This step is important because it ensures that your battery has reached its maximum capacity, allowing you to accurately assess its voltage. The charging time will vary depending on the type and size of your battery, but it is generally recommended to charge it for at least 12 to 24 hours.

Initial Voltage Reading:

Once your battery is fully charged, you can take an initial voltage reading. Connect a voltmeter to your battery and note the voltage. A standard car battery with six cells should have a reading of 12.6V when fully charged. If your battery has a voltage between 10V and 12.6V, it indicates that it can be reconditioned. A reading below 10V usually means that the battery needs to be replaced.

Letting the Battery Sit:

After taking the initial voltage reading, let the battery sit for a few days. This step is crucial because it allows you to assess the battery's ability to hold a charge. A good battery should be able to maintain its voltage even when not in use.

Final Voltage Reading:

After the resting period, take the final voltage reading using your voltmeter. If the battery has successfully held the same voltage as the initial reading, it is an indication that the reconditioning process was successful. This means that your battery is now ready to be used again and should perform optimally.

Periodic Voltage Checks:

Even after successful reconditioning, it is important to periodically check the voltage of your battery. This will help you monitor the battery's performance and identify any potential issues early on. Install the battery in your boat and regularly measure its voltage, especially after periods of non-use. This proactive approach will help ensure that your battery remains in good condition and reduce the chances of unexpected failures.

Load Test (Optional):

For added assurance, you can perform a load test. Reinstall the battery in your boat and turn on the vehicle. With the high beams on, test the battery voltage under load after a few minutes. If the voltmeter reads around 9.6V, congratulations! You have successfully reconditioned your boat battery, and it is now capable of handling a load.

Frequently asked questions