Jumper Cables Melted – Top 3 Reasons Why

This article should help you understand the reasons why your jumper cables melted and show you the safest way to use them if you ever find yourself needing to jump-start a car.

Learning how to jump-start a car with jumper cables is an important car skill to have. It’s also one of those skills that you hope you’ll never need, but if the time comes when you have to use them, they can save your butt and the butt of someone else.

Unfortunately, there are times when the intensity of a short circuit is so great that it can melt jumper cables before they have time to complete the circuit. If you’ve ever seen melted jumper cables, you know that it’s a pretty scary sight.

Why did my jumper cables melt?

It is most likely because of a couple of common mistakes. The first and most obvious mistake is attaching them to the wrong battery terminal. A crossed or reversed jumper cable will result in an electrical discharge which can generate excessive heat on the wires and melt the insulation on your jumper cables.

Poor connections between the two sets of batteries may also be causing this issue. A loose connection on either end or poor quality jumper cables themselves could lead to melting by increasing resistance for electricity flow from one set of terminals to another.

Finally, cheap materials like a copper wire inside your jumpers might just melt if they’re under too much voltage.

1. Crossed/reversed jumper cables

The first obvious reason why you’re several cables melted is that you were trying to start your car with the cables crossed. Do not do this! The cables will melt together and possibly hurt you or damage your car.

If they’re cool now, be thankful; but learn from this as it could have been a terrible experience if it happened while the cable was hooked up to the battery.

When you connect your jumper cables incorrectly, it will reverse the polarity for a few seconds. This will cause the current to flow in the opposite direction through the dead battery. The cables and clamps will then heat up as the result of delivering a reversed current.

If you accidentally touched a crossed jumper cables together, you would feel a slight tingle or shock. It depends on the amount of current flowing through them at the time.

If this happens, very quickly uncross the cables so that their polarity is back to normal. And then take your hands off immediately because they will continue delivering current until it reaches zero.

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Jumper cables have positive and negative ends. 
Alyssa Powell/Insider

2. Loose connections

If you are using quality jumper cables, and they haven’t been damaged through misuse or improper storage, poor connections at either end might be the cause why the jumper cables melted. Loose battery terminals can result in a situation where their resistance is so high that it causes heat to build up as the current attempts to flow across them.

Loose connections can also cause short-circuiting, which will also cause intense heat and could damage your car’s electrical system. When this happens near you, it could cause a burn or shock and potentially catch something on fire. 

The best way to test for loose terminal connections is to lightly smack them with your hand. If they are loose, you’ll feel a slight give before they snap back into place.

If you removed the battery from its tray for some reason, it’s even more important to keep an eye on the connections for looseness.

3. Cheap or damaged jumper cables

Avoid cheap jumper cables with aluminum materials. They are too thin and can result in a meltdown. They also might not be making good contact so you may get no power from it at all.  The thickness of the wires used in the jumper cables is also very important. The thinner the wires are, the easier they will be to melt.

The best jumper cables are usually made of high-quality copper. They won’t melt easily under any circumstances, and the springs inside them will deliver plenty of power even at long distances.

It’s a good idea to get a good set of jumper cables once you start driving, especially if your vehicle is older since it could save you and others quite an experience! You can find them in most auto parts stores and even online.

What we recommend

Don’t want to experience jumper cables melted in front of you? We highly recommend the NOCO Boost Pro Jump Starter Box.

This compact and portable jump starter for your vehicle is perfect to have on hand in case of an emergency. It features spark-proof technology which helps prevent fires, reverse polarity protection when the clamps are not connected properly. It’s small enough to fit under or behind a seat if you need extra space during travel but big enough that it can provide power with a 12V plug (included).

This ultra-safe product also comes equipped with an advanced integrated voltmeter so you know just how much charge there is as well as remote power capabilities through its built-in plugs – making this one indispensable device for any driver.

This UltraSafe jumper pack provides all the essentials needed while still being lightweight and extremely portable.

How to jump-start a car safely

Avoid asking yourself “Why did my jumper cables melt?” in the future. To safely jump start, follow these steps:

  1. Take out your jumper cables.
  2. Place both vehicles in Park or Neutral and shut off the ignition in both cars.
  3. Engage both parking brakes as well.
  4. Attach one of the red clips to the positive terminal of your battery.
  5. Attach the other red clip to the positive terminal of the other car.
  6. Attach one of the black clips to the negative terminal on the other battery.
  7. Attach the last black clip to an unpainted metal surface on your car that isn’t near the battery.
  8. Try to start your vehicle.

We hope this article helped your understanding of jumper cables a bit more, and we hope you won’t experience jumper cables melting anytime soon! If you think about it though, you probably won’t have this problem if you learn how to jump a car and invest in good quality jumper cables.

You should also check out our article on How Long do Car Batteries Last.

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