If your car won't start, or sometimes won't start, you may have a problem with your car's battery cable. The battery cable carries electric current from the car battery to the starter, then to the car's electrical system. Thus, the car can run electrical devices such as radio when it is off and provide energy to the starter to start the engine. A damaged battery cable can reduce or cut off the electric current flowing to the starter so that the car won't turn on or off after a short start. Replacing the battery cables is the first low-cost step in dealing with electrical current problems in your car, and maybe even solving them.
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Part 1 of 3: Locating the Battery Cable
Step 1. Put on safety glasses and gloves
You must wear the proper gear before handling a car or truck. Car batteries contain a mixture of sulfuric acid and water that can cause serious eye injury.
- Batteries can break if not installed properly so that the acid/water inside can get in the eyes.
- Wear latex gloves to make it easier to clean your hands when you're done repairing your car. However, if it's not there, it's not a problem.
Step 2. Make sure the car is turned off
You should check the car to make sure it is dead before replacing the battery cables. You will be dealing with the car's electrical system so electric shock attacks and car damage can occur if the car is left running.
- Remove the key from the ignition gap (ignition) to ensure the car does not accidentally start when you are working on the car.
- If your car has a manual transmission, make sure the parking/hand brake is installed.
Step 3. Find the car battery
Car manufacturers put batteries in various places for a variety of reasons. Most car batteries can be found on the left or right near the front or nose of the car. Car batteries usually appear as a black box with two metal terminals sticking out of the top and wires attached. Make sure the metal rod of the hood can support the weight of the hood before removing it so it doesn't fall and fall on you and hurt you. The car battery may be under the hood or in the trunk.
- Some car manufacturers put batteries in the trunk to save space and increase weight distribution.
- If you can't find the location of the battery, consult the car's user manual. This book will list the location and how to access the battery.
Step 4. Determine the positive and negative terminals
After finding the battery, you need to distinguish the positive and negative terminals. Car batteries are usually colored according to their terminals: red for positive, and black for negative. In some cases, both wires may be black, but the box is red and black or accented at the ends of the wires.
- If you don't see a distinguishing color, try determining the negative wire by tracing it from the battery. The negative cable is connected directly to the car body or engine block, while the positive cable is connected to the starter.
- The battery should have a label with the symbols + and –. The plus symbol indicates the positive terminal and the line symbol indicates the negative terminal.
Part 2 of 3: Removing the Old Battery
Step 1. Remove the box or tape covering the end of the cable
Usually you will find another cable connected to the battery cable using electrical tape (especially on the positive side). Sometimes these cables are held tightly with plastic or metal retainers. Do not remove this cable, but cut any tape blocking your access to the bolts that keep the wires securely attached to the terminals.
- If the ends of the cables are tucked away in a plastic box that distinguishes between negative and positive wires, this box can be opened by squeezing a few clips on either side of the box.
- Be careful not to cut the wires when trying to reach the bolts.
Step 2. Disconnect the negative cable
The negative wire, also known as the ground cable, must be the first wire to disconnect. Once removed, the car's electrical circuitry is no longer complete, and the dashboard, interior, or engine compartment lights will instantly turn off. This indicates the battery is no longer connected to the car and providing power.
- You will need to loosen the bolts that secure the wires at the terminals, but don't let them loose.
- If the associated bolts are stuck or won't turn, try spraying with WD-40. This product will eat some of the rust and oxidation so that the bolts move more freely.
- Negative wire SHOULD NOT touch the positive terminal.
Step 3. Disconnect the positive cable
The negative wire is one of the wires that is most often removed from the terminal, so the positive wire is usually more difficult to remove. Because the positive wire is disconnected from the battery, current is no longer flowing in the car's electrical circuit so the battery can be removed.
- Secure the ends of the wires so they don't touch the battery terminals again.
- If the car battery is in the trunk, the positive cable will be attached to another connector near the body of the car. You can simply unplug it there.
Step 4. Remove the battery
Some car batteries don't have to be removed for cable replacement, and usually aren't necessary. However, we still recommend removing the battery to make the cable replacement process easier. Removing the battery can increase the workspace space and prevent the battery cables from touching the terminals again, thereby avoiding the risk of accidents.
- Many cars have brackets that can hold the battery cables. To remove it, there are usually two bolts that must be removed.
- Be sure to place the battery in an upright position after removing it from the car.
Step 5. Disconnect the negative cable first, followed by the positive cable
Start by tracing the cable from the loose end of the terminal, to where the cable is bolted to the engine block or car body. Make a note of these cable routes so you can install new cables the same route. When you find it, use a wrench to remove the bolt that holds the negative wire. After that, repeat the process on the positive cable whose end is attached to the starter.
- Make sure the car is cold when you work to avoid burns.
- You must remember/note the wiring route in the engine bay so as not to disturb the moving parts of the machine when changing cables.
Step 6. Compare the old and new cables
If the positive and negative cables have been removed, compare them with a new battery cable. If you purchased a special cable for your car, the length and connectors on the ends of the cables must be exactly the same. If different, return to the relevant store to replace it with the right cable. If you're using a universal cable that's cut in length, use the old cable as a reference.
- Usually the new battery which is slightly longer than the old battery does not cause any problems. However, it's a different story with a short cable.
- Be sure to check that both ends of the new cable connector match the old cable for easy installation.
Part 3 of 3: Installing a new Battery Cable
Step 1. Prepare for the new cabling
If there is a protective plastic box on the end of the old cable, remove it and attach it to the end of the new cable. You also need to make sure that there is no paint or dirt on the ends of the new wires prior to installation.
- The connection of the two ends of the cable must be metal so that it can conduct electricity.
- You can use a steel bristle brush to clean the ends of the connectors so they conduct electricity properly.
Step 2. Connect the positive wire with the starter
Use the same screw as the screw on the old wire to connect the new wire to the starter. If the bolt is rusty, you should clean it with a steel brush so that the bolt can conduct electricity properly. If it's too rusty, maybe the bolt needs to be replaced.
- Make sure the bolts are tight enough so they don't move when the car is running.
- Thread the new positive wire through the same path as the old wire.
Step 3. Attach the negative wire to the car body or block
Locate the hole that the old negative wire was connected to and use the same screw to connect the new wire. Again, make sure the bolts are in good condition so they can hold the wires while they conduct electricity properly.
- Thread the new negative wire in the engine bay through the same route as the old wire.
- Use a flashlight to make sure none of the wires touch the belt. The engine belt rotates at high speed under the hood and can damage the battery cables.
Step 4. Put the battery back in the car
When the two new cables are in place, it's time to put the battery back in its place. Make sure the two new wires do not touch the battery terminals while they are inserted to prevent electric shock. If the battery terminals appear to be oxidized or corroded, use a small steel brush to clean the connection area before putting the battery back in the car.
- Install the screws on the rack that hold the battery back in place and secure the battery.
- Make sure you place the battery the same way it was removed so that the positive terminal is close to the positive wire, and the negative terminal is next to the negative wire.
Step 5. Connect the positive cable with the battery
You may need to purchase a corrosion inhibitor that can be attached to the battery terminals before connecting the new wires. This ensures a strong connection to the battery and is not disturbed by corrosion deposits in the engine housing. Squeeze the inhibitor on the terminals, then slide the positive wire connection until it fits tightly.
- Tighten the cable by tightening the screw that was previously loosened to remove the old cable.
- Make sure the cable is firmly connected. Loose cables can come off when the car is used to drive, causing the car engine to stop.
Step 6. Connect the negative cable
Don't forget that if the negative cable is connected to the battery, the car's electrical circuit will be complete and you can start the car again. So make sure all other connections are tight before doing this step. You can also use a corrosion inhibitor on the negative terminal. After the negative cable is connected, the car will be able to start again.
- Be careful when touching the negative wire to the terminal because sometimes sparks may appear.
- Tighten the cable tightly so it doesn't wobble and come loose.
Step 7. Start the car
Make sure the cable is plugged in properly by starting the car. If the car does not start, there may be a cable that is not tight enough and is not conducting electricity to the starter. If the engine tries to start but fails, the battery may not have enough charge. If the car fails to start, recheck the cable connections at both ends.
- If the two cables are properly connected and tight, remove the battery again and take it to a repair shop. Workshop staff can test and charge the battery to confirm its condition.
- If the cable is loose, try tightening it and try again.
- If the car starts smoothly, your job is done.
