How to rebuild a car battery when cell is dead

Car batteries are the lifeline of vehicles, powering all the electrical systems that make modern cars the amazing machines they are. However, like all batteries, car batteries eventually lose their ability to hold a charge, causing them to need replacement. One of the leading causes of this is a dead cell within the battery. When this happens, many people assume the battery is beyond repair and replace it. However, it is possible to rebuild a car battery even when a cell is dead.

The process of rebuilding a battery involves breaking it down and rebuilding it from scratch. This might sound daunting, but in most cases, it’s an easy process that can be done at home with the right tools and some basic knowledge. By rebuilding your dead battery, you can save money and reduce your impact on the environment by avoiding the disposal of a battery.

In this article, we will walk you through the steps you need to take to rebuild a car battery when a cell is dead. From the tools you’ll need to the rebuilding process itself, you will learn what you need to do to get your car battery back up and running again. So, put on your safety goggles, grab your tools, and get ready to rebuild your car battery.

How to Rebuild a Car Battery When Cell is Dead

Step 1: Safety First

Before starting any work on the car battery, make sure to put on safety goggles and gloves. Car batteries contain sulfuric acid, which can cause burns and injury if it gets on your skin or eyes.

Step 2: Remove the Battery

Take the car battery out of the car and place it on a flat and stable surface to work on. If you have a newer car, consult the owner’s manual first, as some battery systems require special tools or knowledge.

Step 3: Discharge the Battery

Use a voltmeter to check the battery’s voltage. If the voltage reads above 12 volts, proceed with discharging the battery. Use a light bulb or resistor to slowly drain the battery until the voltage reads around 11 volts.

Step 4: Remove the Dead Cell

Use a battery load tester to identify the dead cell. Then, use a battery charger and an automotive knife to remove the dead cell from the battery. Make sure to wear gloves and goggles.

Step 5: Add the Replacement Cell

Purchase a replacement cell that matches the type and size of your battery. Clean the battery terminals and the new cell connectors, then use a soldering iron to connect the new cell. Make sure to follow the manufacturer’s instructions.

Step 6: Recharge the Battery

Recharge the battery with a battery charger until it reaches a voltage of 12.6 volts. Do not overcharge the battery, as this can lead to damage or explosions.

Step 7: Test the Battery

Use a load tester to test the battery’s capacity. If the battery is still not working properly, you may need to repeat the steps or consult a professional.

By following these steps, you can save money by rebuilding your car battery instead of purchasing a new one.

Assessing the Damage

Visual Inspection

One of the first things you should do is visually inspect the battery for any signs of damage or leakage. Check the top of the battery for any cracks or breaks that could indicate damage. Also, look for signs of leakage around the terminals or the bottom of the battery, which could cause corrosion or other problems.

Testing the Battery

The next step is to test the battery using a multimeter or battery tester to check the voltage and capacity of the battery. This can help you determine whether the battery is still functioning properly, or whether it has any dead cells that need to be replaced.

Tip:

• If the battery is completely dead, it may be best to replace it with a new one rather than trying to rebuild it.
• Always wear protective gloves and eyewear when working with car batteries to avoid accidents and injuries.

Replacing the Dead Cell

Step 1: Identifying the Dead Cell

The first step in replacing a dead cell in a car battery is to identify the cell that is no longer functioning properly. This can be done using a multimeter to test each cell individually.

Step 2: Removing the Dead Cell

Once the dead cell has been identified, it must be removed from the battery. This can be done using a battery puller or a pair of pliers. Be careful not to damage the battery terminals or the adjacent cells.

Step 3: Installing the New Cell

After the dead cell has been removed, a new cell can be installed in its place. The new cell should have the same voltage and capacity as the cells surrounding it. It is important to connect the cell correctly, with the positive terminal facing the positive terminal of the adjacent cell and the negative terminal facing the negative terminal.

Step 4: Sealing the Battery

Once the new cell is in place, the battery must be sealed again. This can be done using battery sealing compound or by wrapping the battery in plastic wrap. Ensure that all the battery terminals are free of any residue or corrosion before resealing the battery.

Step 5: Charging the Battery

Finally, the battery must be charged to its full capacity before use. This can be done using a battery charger or by driving the car for a sustained period of time. It is important to monitor the battery closely during this process to ensure that it is not overcharging or undercharging.

Testing Your Rebuilt Battery

Step 1: Test Voltage

Before installing your rebuilt battery, it’s important to test its voltage. Use a multimeter to measure the voltage across the positive and negative terminals of the battery. A fully charged battery should read around 12.6 volts. If your battery reads a lower voltage, it may not have enough charge to start your car.

Step 2: Load Testing

Load testing is an essential part of battery testing. The test simulates the electrical load of a starter motor to determine if your battery can handle the load. Connect a load tester to your battery and apply a load for 15 seconds. If your battery can maintain a voltage of at least 9.6 volts during the test, it’s considered to be in good condition. If your battery fails the load test, it may not be able to start your car.

Step 3: Check Acid Levels

If you have a lead-acid battery, it’s important to check the acid levels before installing it. Use a hydrometer to check the specific gravity of the electrolyte. The specific gravity should be between 1.265 and 1.299. If the specific gravity is lower than 1.200, it means that the battery doesn’t have enough acid and needs to be refilled.

Step 4: Recheck After Installation

After installing your rebuilt battery, it’s important to recheck its voltage to ensure that it’s holding a charge. Wait at least 30 minutes after installation before testing the voltage. Measure the voltage across the positive and negative terminals again. A fully charged battery should read around 12.6 volts. If your battery reads a lower voltage, it may not have enough charge to start your car.

By following these steps, you can ensure that your rebuilt battery is functioning properly and will be able to start your car reliably.