Symptoms of a bad car battery negative cable

Most people who own cars understand the value of their cars’ battery, especially when it comes to starting the car. However, only a few know the role of the battery cables. The cables attached to the battery are an important component of the vehicle’s electric system because they connect your car’s electronic system with the battery. 

Most batteries are made from heavy-duty, insulated wires to carry high loads of current with fewer challenges. Though they have a simple design, their failure can result in many issues. 

When the battery is disconnected for servicing, the negative cable is removed first. This step is extremely important because it prevents short circuits and damage to the wiring.

What is the role of a negative battery cable?

The negative battery cable attaches to the metallic frame of your vehicle. Like other electronics, the circuit must be complete for the car to start. If the connection to the negative terminal, positive terminal and metal frame are incomplete, then the car will not power up. The negative battery cable completes the circuit from the battery and delivers power to your vehicle. 

Top symptoms of a bad car battery negative cable 

1. Corroded negative battery terminal 

One of the top symptoms of a bad car battery negative cable is the negative terminal’s corrosion. This is caused by the acidic vapor, which occurs when the battery is exposed to very high temperatures. The vapor will corrode the negative terminal, and if not checked, the corrosion will build on the terminals and impede the flow of electric current. This will result in increased resistance on the contact surface. Other times, the vapor can seep into the negative cable and corrode it from the inside. Ensure you replace the cable once it shows signs of lagging in performance.

2. Car Won’t Start

For your vehicle to start, the battery cables must be connected to the vehicle’s frame and car starter. But if the negative battery cable is bad, then the connection will be incomplete. Therefore, the car won’t start, and the battery might not have any issues. Instead, the negative battery cable, which is usually black, is not providing a good connection to your car’s metal frame.

3. Low Voltage Battery 

Well, if your battery has a low voltage, then it could be signs of a failing negative cable. A strong connection is required to transfer power from the car alternator to the battery. This is possible only with good cables. Therefore, if your negative battery is bad or failed, the current won’t reach the battery due to the poor or loose connections to the negative battery terminal.

4. The battery cable is damaged

One of the symptoms of a bad cable is a damaged or frayed one. Don’t forget to monitor your battery cables regularly and if they are damaged, consider replacing them. You may opt to repair them, but it’s cheaper to replace, and it’s a long-lasting solution. Good battery cables are smooth and do not show any signs of corrosion or nicking on them. 

5. A dead battery

When the car’s battery doesn’t take any charge, then it may not be damaged. Without a good ground, the battery won’t take charge. But the battery can also be dead if the alternator has issues or when the negative cable is damaged or frayed. However, if the two parts are in good condition and you are still experiencing challenges, then it’s likely that the ground strap is faulty or loose. 

6. Headlights have low intensity

If you see that your car’s headlights have low intensity then this can be caused by a bad negative cable from your vehicle’s battery. So, be sure to check the cable if you encounter this issue.

How to properly disconnect the negative cable from the battery

If for some reason, you want to remove the battery you should follow the steps below. Disconnecting the negative terminal of the car battery is, of course, a safety measure. The negative terminal is marked with a “-” and is black. To properly disable it, you need to follow several steps:

  • Before starting any work, turn off the engine and remove the ignition key. This step may sound elementary, but because it is too obvious, it is often overlooked. Please note that for any mechanical intervention, the vehicle must be parked in a level and well-lit place for all work to be completed successfully.
  • Most batteries are usually found near the front of the engine. It should be noted that in some cars the batteries are located under the engine, so they can be more difficult to find.
  • Once you find the battery, you should find its negative terminal, the black cable attached to it. A red or blue cable will also be found nearby, which is a positive lead and should not be removed.
  • The two cables are attached to the battery with a spring clip and can be easily removed. It is advisable to wear safety glasses during this operation to protect your eyes.
  • Sometimes the negative cable will attach to the battery in a way that removing it is not as easy as it might seem. In such situations, it is necessary to move the cable back and use a socket wrench to release the terminal.
  • After releasing it, pay close attention to the negative cable, do not touch the battery, because it may activate the car’s electrical system. Therefore, you need to keep the negative cable away from the battery, otherwise, it may cause electric shock.

How to connect the negative cable to the car’s battery

After completing the mechanical work that was intended to be done in the car, you need to reconnect the negative cable to the battery.

  • Simply slide the cable back in place and tighten the clip that holds it. Then put the battery back in place if it was removed and close the hood of the car.
  • Please note that when performing any kind of maintenance and repair work on a vehicle, the use of all protective equipment such as safety glasses and safety gloves is critical to ensure the best possible protection.
  • Although it is a simple task to disconnect the vehicle terminals, batteries contain acids and this can be very serious if measures are not taken.

Frequently asked questions about the battery’s negative cable

What happens if the negative battery cable is loose?

The cables will get hot, and the heat can even melt the battery terminals

Can a bad battery cable cause a car to stall? 

Yes, a bad cable can stall your car. 

How do you test negative battery cables?

Attach the cable to the multimeter and the negative battery terminal. It should have a reading of less than 0.3 or less if it’s still in good condition. 

Why is the negative battery cable hot?

The cable is hot because the connection is loose, yet it’s carrying a high amount of power to start the car.

How do you tighten negative battery cables?

For a proper tightening you should use a wrench to tighten the bolts. This operation is easy to do and you can do it by yourself.

How much does it cost to replace bad battery cables?

The average cost of battery cables is $187-$193. But there are additional labor costs that you should check when you go to a specialized workshop


Once you identify that the negative cable has a problem, the solution is to replace them. I would not advise you to replace the battery cables by yourself unless you really know what you have to do, and this requires a lot of knowledge in other fields.

Go to a professional to handle the replacement. This will increase efficiency and ensure your car doesn’t encounter any issues down the road.

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