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Battery Fuse Blown – Symptoms & Fixes (Explained)

Batteries are a source of energy made by connecting multiple electrochemical cells by external connections. Batteries provide energy for portable devices such as flashlights, laptops, watches, etc. Batteries that power high-power-consuming machines usually come with a fuse.

What is the purpose of a battery fuse?

A fuse is a safety device, also known as a sacrificial device, as it can only work once. The purpose of a fuse is to break an electric circuit when the current goes above safe levels. There are various fuses with different ampere ratings, such as 3A, 5A, 15A, etc.

A fuse has a thin strip of a conductor. When you connect it to a circuit, current flows through the conductor. If the current level goes above the amperage rating, the conductor in the fuse heats up and breaks, which breaks the circuit.

Batteries that power large devices and machines also come with a fuse. Batteries have a fuse that protects the device from sudden current surges. If a machine suddenly pulls a lot of current from the battery, the battery fuse breaks the circuit to prevent any harm to the device.

How to tell if the battery fuse is blown?

A blown battery fuse can be recognized by connecting it to a circuit. If you plug a battery into an electric circuit and the components do not work as intended, this means that the course is incomplete. An incomplete circuit will indicate that the battery fuse has blown.

A battery fuse in a car may blow for various reasons. You can tell if the battery fuse is blown by observing the following:

No power in the engine:

If the battery fuse blows, the car’s engine will not start. The car’s engine will neither crank nor start as the battery is not connected. When the fuse breaks, it breaks the relationship between the battery and all the car components. 

As a result, the engine will not start if you press the start button.

Lights are not working:

Broken fuse will break all relations with the battery and other components of the car. The lights and headlights will not function properly and will not turn on.

If you see that your lights are not working or the engine is not starting, it could indicate a broken battery fuse.

Burning smell:

Usually, battery fuses are covered with plastic covers. So, when the fuse heats up, the plastic insulation melts. The melting insulation produces a burning smell. If you get a burning smell while trying to start your car, it could be that the battery fuse has blown.

Dashboard light:

Modern cars can notify the driver about battery issues. If you see the battery sign pop up on your dashboard, it could be that your vehicle is not getting power from the battery. No power from the battery could further indicate that the battery fuse has blown. 

A blown battery fuse will disconnect the battery from the car.

How do you check a battery fuse?

Checking a battery fuse is simple. Follow the tips below to check a battery fuse:

Checking the car dashboard:

Start the car. If you see that the battery sign lights up on your dashboard, that could mean a problem with the battery. 

This sign indicates that the battery is either not working or is not connected. In most cases, this light indicates that the battery fuse has blown.

Starting the car:

When you try starting the vehicle, if you see that the engine is not starting, the battery could be malfunction. The engine not starting can indicate that the battery is not working as intended. 

If the lights are also not working, that will signal a problem with the battery. In most cases, it means that the battery fuse has blown.

Checking under the hood:

Check under the engine cover for any problem. Opening the hood, you will have access to the engine and battery of the car. There, check the main fuse box for the battery fuse. 

Once you have located your battery fuse, check if the wire in the fuse is still intact. If it is not intact, it has blown.

Checking the battery fuse:

You can check the battery fuse yourself. With the help of a multimeter, you can check if there is any resistance between the two prongs of the battery fuse. If there is no resistance, the fuse is intact. 

If you find resistance, the fuse has blown and needs replacement.

Can a blown fuse kill your battery? Can a blown fuse drain the battery?

As mentioned before, a fuse has a conductor contained inside a plastic or glass body. When the conductor heats up and breaks, the circuit is disrupted, and thus, no current flows through the circuit. Since no current flows, there is no power transmission from the battery.

As there is no current flowing throughout the circuit, the battery is not drained. The battery will not drain because the fuse disrupts the electric circuit. Therefore, a broken fuse does not drain your battery.

However, if it is a rechargeable battery then, the charging component may also not work. If the charging component of the battery is on a different circuit, then the battery will be charged even if the battery fuse blows. 

In that case, the battery will not able to provide any energy to the engine and other components.

Can you repair a blown battery fuse?

A blown battery fuse will make your car immobile. Without the battery fuse working, the engine and lights will not work. As a result, it is mandatory to fix the fuse of your car battery as soon as possible.

Although repairing a blown battery fuse is an easy task, it should be done by an expert. If you think that your car has a blown battery fuse, you should consult a car mechanic who specializes in electricity.

Repairing a blown battery fuse does not take long. All you need to do is replace the battery fuse with a new one. After that, make sure the new fuse works.

Replacing the blown battery fuse will require bodily contact with the car components. The parts could be electrically hot or warm to the touch. Therefore, it is ideal to use rubber gloves as protection.

How to fix a blown battery fuse? How to replace the battery fuse?

Fixing a blown battery fuse is simple. Follow the steps below to replace the battery fuse yourself.

Preparations:

As mentioned earlier, replacing the blown battery fuse will cause bodily contact with the car. Ideally, you should let the car cool down and engage the parking brakes. Also, since you will be working with electrical components, wear rubber gloves. Rubber gloves will provide insulation.

Locate the fuse box under the engine cover:

Under the hood of the car, you should see the fuse box. If you do not find it, go through your car manual to locate the fuse box. After you have located the fuse box, remove the top cover of the fuse box to expose all the fuses inside.

Identify and check the main battery fuse:

Using the fuse box cover, identify the main battery fuse. Compare the readings on the fuse box cover and the battery fuse body to make sure you have identified the correct fuse.

Remove the old battery fuse:

Once you have identified the main battery fuse, use pliers and gently remove the fuse from its socket. Once removed, check the fuse with a multimeter to ensure that the fuse has blown. Also, if you see that the wire between the prongs has melted, you will know the fuse has blown.

Replace the battery fuse:

Take the new fuse and compare the markings on both the battery fuses. Make sure that the readings match. You may match the container colors too but that is not necessary. After making sure both the fuses have the same amperage ratings, push the fuse into the socket. 

The new fuse has been installed. After you have installed the main battery fuse, start the car to make sure the fuse works.

Final thoughts

There are several symptoms of a blown battery fuse. Replacing the main battery fuse is simple, and you can do it yourself. However, experts advise consulting a car mechanic as it involves electric components connected directly to the battery. If you choose to do it yourself, take proper precautions.