Why Are My Jumper Cables Smoking?

If you use cheap cables or connect the terminals wrong, you may melt the insulation on the cables and cause them to smoke.

Cheap Cables and the Problem with Using Them

With cars, as with many things, you get what you pay for. Cheap parts and accessories are often less reliable and less durable than higher-priced options. This is especially true of jumper cables since the amount of electricity flowing through them is high and cheap ones use inferior materials. As such, they are only good in certain circumstances.

If your battery is completely dead, and you’re charging it by attaching it to a running car, then cheaper cables may work just fine. But if you try cranking your car while it’s still attached and you may see a column of smoke rising from under your hood.

Better, often pricier, cables are made with thick copper wire (0 or 00 gauge) and thick insulation around the wires. These two materials both help keep too much heat from building up and causing problems. They can handle the amount of electrical current better and are better suited to general jump-start usage.

What Are Cheap Cables Made of and Why Is It a Problem?

Cheaper cables are often made with thinner gauge wire, usually copper or aluminum, and have less insulation, meaning they are only suited for charging while the car is off. The current from a jump start is too much for the wires to handle, generally speaking, and the insulation may melt and begin to smoke.

Dangers of Using Cheap Jumper Cables

As the saying goes, where there’s smoke, there’s fire, and that can quite literally be the case if your cables start to smoke. The heat from the electrical current may cause burns to those handling them. They may also ignite flammable materials nearby or that come in contact with them, such as clothing.

Additionally, if the insulation melts off, you’ve got exposed wires to deal with. That presents a rather significant risk of shock should you handle the wire while it’s still alive. Be sure to use good, thick gloves that will insulate you against electricity if you need to remove jumper cables with exposed wires.

Nobody wants to get lit up like a lightbulb because they panicked and didn’t think at first. With those hazards to watch out for, it’s probably better to just spring for the slightly nicer ones that won’t potentially burn or shock you.

Connecting the Terminals Wrong

Another reason your jumper cables are smoking is connecting the wrong terminals when hooking up two cars for a jump start. This causes a short circuit and overloads the wire, causing heat to build up. The excess heat melts the insulation, which begins smoking.

This presents all the same dangers mentioned above, but is not related to the quality of your cables, but rather operator error. It’s a common mistake to make, and caution should be taken every time you jump a car to connect the terminals properly.

How To Connect Battery Terminals Properly and Jump Your Car Safely

Connecting two car batteries is simple, though easy to mess up, task. Essentially, you want to connect like with like, in this case, positive with positive and negative with negative. Most batteries and all cables are color-coded, but some batteries are not. Just be sure that the same color clip matches on each battery- red on positive, black on negative.

To identify the positive and negative terminals without color-coding, look for a plus symbol for the positive terminal and a minus symbol for the negative terminal.

First, connect the red clips to the positive terminals, beginning with the dead battery. Then, without letting them touch, connect the black clips to the negative terminals, again beginning with the dead one. Once they are secured, start the car with the dead battery. If everything is hooked up right, your car should start right up.


If you see smoke coming from your jumper cables, immediately turn off the car feeding the current and remove the cables. Smoking or melted cables endanger your safety, so using high-quality jumper cables is essential for safely jumping your car. Also important for safety is the use of the proper technique for attaching the cables to the car batteries.