Is There A Fusible Link Between Alternator And Battery?

Is There A Fusible Link Between Alternator And Battery

Older vehicles use fusible links because they are cheap wires with high-temperature insulation. Their reliability makes them appealing. However, many manufacturers prefer to install inline fuses in modern vehicles. They are more accurate. But that doesn’t apply to every model. You should check the manual to determine whether your vehicle uses a standard fuse or a fusible link. You can’t go wrong with either option.

You can trust reputable manufacturers to use the best over-current protection device for your vehicle.

What Is The Purpose Of The Fusible Link Between The Alternator And Battery?

Is a fusible link a fuse? If it is, why do they use the term ‘Fusible Link’ instead of ‘Fuse?’ This is everything you need to know about fusible links and what they do:

1). What Is A Fusible Link?

As you probably guessed from the name, a fusible link is an insulated wire. It has a conductive core that melts when exposed to excess current. This prevents that excess current from reaching the battery.

In that regard, it doesn’t differ that drastically from a conventional fuse, at least in terms of its function.

2). What Is The Fusible Link Made Of?

The fusible links made by Allied Wire and Cable are stranded bare copper. They use Hypalon rubber insulation, and their sizes range from 22AWG to 8AWG. However, your local manufacturers and retailers may prioritize different materials and sizes.

3). What Makes Fusible Links Special?

Fusible links are low-voltage wires. They are designed to protect delicate wire harnesses from sizable electrical currents. Fusible links are supposed to be the weakest point in the system. You want them to fail before every other component when they encounter a surge.

This is why fusible links are thinner than the wiring harnesses they protect. However, Easy Bom has noticed that these low-voltage wires can tolerate temporary current spikes. The platform has also published pictures of fusible links if you’ve never seen one.

You can trust the lines to transmit high-current electricity without blowing. At the same time, they will respond rapidly to dangerous spikes by melting.

4). How Does A Fusible Link Work?

Electrical components are designed to transmit a specific volume of current. That includes wires. They tend to overload and melt when you exceed their capacities. You can’t rule out the possibility of a fire starting.

A fusible link is constructed from an alloy that melts when it encounters more current than it can withstand. Usually, melting is a bad thing in a wire. However, you want the fusible link to melt because it breaks the circuit. This stops the current from flowing, which, in turn, protects the rest of the circuit from the electrical surge.

5). Where Is The Fusible Link?

A melted fusible link is good because it stops surges by breaking the circuit. However, a broken circuit is inconvenient because the current won’t flow. The battery will die. You solve this issue by replacing the fusible link.

But you can’t replace the fusible link if you don’t know where to find it. Unfortunately, manufacturers are not obligated to keep the fusible link in a specific place. Therefore, the location may vary.

EricFromCT, a mechanic on the Just Answer platform, encourages consumers to check the cable harness running between the positive battery terminal and the alternator. The vehicle’s manual will provide a more definitive answer. This assumes that your vehicle has a fusible link. Many cars use an inline fuse.

Choosing The Right Fusible Link: What Factors Should I Consider For Alternator And Battery Safety?

You don’t want to select the wrong fusible link for your vehicle. Your wiring harness and its connected components may suffer irreversible harm. Keep the following in mind:

  • Use The Old Fusible Link

It is common practice to find a replacement fusible link that matches the size and length of the dead fusible link. This is because manufacturers engineer the fusible link with a size and gauge that fit the vehicle’s distinct demands. Therefore, the specifications of the old and new fusible links should match.

  • Hire A Professional

In the absence of an old fusible link to act as a reference, the wiring depot wants consumers to hire a qualified harness engineer who can use their extensive knowledge of circuit protection requirements and operating conditions to select a suitable link.

  • Look at The Size

If you can’t access a professional, pay attention to the gauge. The fusible link should be four gauges smaller than the harness segment it protects. For instance, a 14AWG harness requires an 18AWG fusible link.

As far as the length is concerned, aim for 6 to 12 inches. Consult the fusible link’s manufacturer about the maximum temperature and voltage.

Signs Of A Damaged Fusible Link? How Can It Impact the Alternator And Battery?

A damaged fusible link is a good thing. It means the fusible link did its job. It protected your vehicle from a surge. But how can you tell that a fusible link is dead or damaged? You will notice the following symptoms:

1). The Battery Will Die

The alternator makes electricity that charges a battery in a running engine. A melted fusible link will prevent the alternator from transmitting its current to the battery. As a result, the battery will gradually drain until it hits zero. This is not a mere inconvenience. You can’t start a car with a depleted battery.

2). The Electronics Will Stop Working

Again, a damaged or blown fusible link breaks the circuit. If the current won’t flow because of a broken circuit, the electronics won’t work. And if they continue to work, their functions will deteriorate. For instance, the lights will dim.

3). The Dashboard Will Alert You

The experts at want consumers to look for a charging system warning light on the dashboard. It will illuminate once the fusible link blows. What if your dashboard doesn’t include a charging system warning light? A fusible link that disrupts the alternator’s functions will trigger the ‘Check Engine’ light.

4). The Fusible Link Looks Damaged

A damaged fusible link will manifest observable signs, such as melted insulation, brittleness, discoloration, a melted wire coating, etc.

How To Ensure A Healthy Connection Between Alternator And Battery?

Start by physically inspecting the fusible link for damage. A broken conductive element points to a damaged fusible link. But if you can’t see any signs of damage externally, yet you’ve observed signs you associate with a damaged fusible link, such as a dead battery, use a digital multimeter to confirm your suspicion:

  • Set the multimeter to ohms.
  • Turn the key in the ignition to the off position.
  • Connect the multimeter’s probes to the terminals of the fuse.
  • You’re trying to test for resistance across the fusible link. A broken fusible link will show infinite resistance.

If the fusible link is dead, use the following steps to replace it:

  • Use the manual to locate the fusible link. You can also check in the vicinity of the battery and the alternator.
  • Disconnect the battery’s negative cable to prevent accidents.
  • Disconnect both ends of the fusible link and remove it.
  • Use the information on the old fusible link’s jacket to find a suitable replacement.
  • Install the new wire in the location where you removed the old wire.
  • Connect the battery.

If the symptoms you noticed with the old fusible link persist, take the vehicle to an expert. They can determine whether you made a mistake while installing the new fusible link or selected the wrong one. They can also determine whether the fault lies elsewhere.

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