Which Car Battery Terminal Do You Connect to First?

When installing your car battery, you have to follow the steps carefully so you do not make mistakes that would affect your battery or car itself negatively. When connecting the battery terminals, the positive one should be connected first. 

Why Should the Positive Terminal Be Connected First?

The reason is that if, while connecting the positive cable with a spanner, you touched the body of the car with a spanner or metal, you would be safe. After all, this way, the electric current will not arc through you. If you connect the negative cable first, then there is a great chance of a hazard. If the negative terminal is connected first, and you make contact with the car via a metal, your body becomes part of the circuit, and the electricity arcs through you. 

Which Car Battery Terminal Do You Connect to First?

What Happens if the Negative Terminal is Connected First?

 Vehicles are negatively grounded; that is, the negative terminal is connected to the car’s frame or engine, so if you connect the negative cable first and then connect the positive cable with a spanner, there would be a short circuit. This could also lead to an explosion or possibly a fire. Connecting the positive terminal first minimizes any sparking and protects you from being a conductor yourself. 

How To Connect a Car Battery

Connecting a battery is a crucial part of its installation process. Batteries have to do with electricity, energy, and sometimes spillable acid, so you have to be careful when handling them. Here are some safety tips to keep in mind before you proceed to the installation steps:

  • Put on safety gear such as safety gloves, goggles, or a face shield
  • Make sure that the area is well lit and ventilated
  • Keep your car battery in a cool place. Avoid heat around your battery
  • Make sure to tighten the refill caps firmly if you use a wet cell battery
  • Always have a fire extinguisher nearby
  • Ensure the keys are removed from the ignition
  • Keep conductive metals away from the terminal except when necessary
  • Remove jewelry and metals such as rings, watches, necklaces, and the like from your body while working on batteries
  • Keep batteries away from children 
  • Consult your manufacturer’s manual for any specific tips 

Steps To Installing Your Car Battery

  • Clean the battery terminals if necessary:

If the battery terminals have corroded or have built up from sulfation, you can use a battery cleaning spray or a simple DIY paste of water and baking soda to clean the terminals, using a soft brush to apply the paste and scrape the area. Then use a wet rag to wipe it clean and wait till it dries. Do the same for the cables.

  • Apply corrosion protection grease to the cables and terminals:

To prevent future corrosion, coat the cable and terminals with anti-corrosion grease or petroleum jelly. There are some gels and creams specially formulated to protect the terminals from rusting. 

  • Inspect the cables for any damage or cracks:

Check for any wear and tear that could cause shock or damage to the battery. Fix or replace where necessary. 

  • Clean out the battery tray:

Locate the battery tray and clean it out where necessary. Ensure to let it dry before you continue. 

  • Align the battery with the tray:

Place the battery right with the terminals aligning with the engine bay before lowering it down into the tray. Batteries have different terminal placements, which is called polarity. Here are the different orientations a battery terminal has:

  • Standard post top: this is the most common type. The positive and negative terminals are located on the top of the battery for easy connection
  • Side post: this design is to reduce corrosion. The cables ends are screwed to the side of the battery
  • Recessed top post: here, the terminals are located on small recesses at the corners. 
  • Carefully lower the battery into the tray:

Carry the battery with both hands, gripping it from the sides, and carefully lower it into the tray. Ensure nothing is getting in the way, and pull the cables to the side if it is obstructing. Some car batteries come with a “hold down.” A hold-down is like a metal hook for securing the battery in place. If your battery has this, pull it over the battery and secure it. Some require pliers to fix- you can also always check your manufacturer’s manual to know to clamp it down. 

  • Connect the battery terminals:

This is the important part of the process of what this article is about. As earlier stated, the positive terminal is to be connected first, followed by the negative. 

To make it easier to follow, here is a list to follow for the connection:

  • Slide the positive battery cable into the positive terminal
  • Press the connector to the terminal until it lies flat in place
  • Using a wrench, tighten the cable onto the terminal 
  • Follow the same process in connecting the negative cables

If you are having issues with reaching either terminal, then you may need to adjust your battery, so it sits right.

  • Get the key into the ignition and start the car.

This helps it run a bit and charge the battery further.

Which Car Battery Terminal Do You Connect to First?


How can I tell the negative and positive terminal apart?

The positive terminal is usually red color, while the negative terminal is usually black. 

Is changing a car battery myself dangerous?

Changing a car battery is pretty easy. To keep safe, you simply need to follow the steps and observe safety precautions.

What is grounding?

Grounding a car battery is a safety measure to create a safer route for electricity to travel from an appliance to the ground. It is connecting an appliance to the earth using a conductor, which is usually a grounding strap. Grounding protects you and the car appliances from explosions, surges, fires, etc.

What happens if my car is not grounded?

Electricity cannot flow if the battery is not grounded. Also, grounding is necessary for charging your car battery. A badly grounded car can cause electrical issues, noise in the audio system, engine control problems, and even a risk of hazards.

Is the ground wire positive or negative?

In a circuit with one battery, the ground is usually negative. However, in cars with negative earth, the car wire will be black, and cars with positive earth will have their car wires red.

What happens if the positive terminal touches metal?

If metal touches the positive post, then it should be connected to the ground. If not, this leads to shorting and can damage the battery. 

What happens if my battery cables are bad?

Your car shows symptoms of bad connection or cable through dimming headlights, slow cranking, difficulty in starting the car, and malfunction of electrical accessories. 

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