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What Are Jumper Cables And Their Voltage?


Have you ever got stuck in a car with a dead battery in the midst of winter? A jumper cable, or a jumper lead, is the miracle product that helps you find a way out of such unfortunate circumstances. Read this blog to learn about the essential characteristics of a jumper cable, the voltage it sustains, the color-coding of jumper cables, how to jump a car, and the reasons to always have a high-quality jumper cable at hand.

What Is a Jumper/Booster Cable?

A jumper cable has a thick electrical cable with tight, thick clips at each end. These cables are used to headstart a car or another type of vehicle by connecting the battery that went out of service due to discharge or malfunction with the battery of a different vehicle. 

Jumper cables are also known under other names, such as jump lead or a booster cable. All of these titles have the same meaning.

Construction and Characteristics of a Jumper Cable

Essentially, jumper cables are insulated wires with thick clips, often called alligator or crocodile clips, for their appearance. These clips help create a temporary electrical connection and connect the dead battery to another vehicle.

Jumper cables typically have thick insulation, such as EPR (Ethylene Propylene Rubber), with excellent resistance to weather, moisture, ozone, abrasion, and mechanical impact. Jumper leads also have stranded copper conductors that make them flexible, which is ideal for the type of application they typically serve. A synthetic semi-conducting tape isolates the conductor of the cable from the insulation to relieve the voltage stress.

Do Jumper Cables Have A Maximum Voltage?

Booster cables do not really have maximum voltage the way it is traditionally understood, even though the manufacturer may assign a Kv rating to the cable. 

The actual limit when using a jumper lead is not voltage but current. In jumper cables, the amount of current that can be safely handled depends on the quality and, most of all, the thickness of the insulation. The thicker the cable, the more current it can handle. The bigger the gauge of the cable, the more current and, as a result, the more voltage the cable can handle. The biggest mainstream size of the jumper cable is 2 AWG. In this size, the cable can handle the maximum ampacity of 165 Amps at 35kV, which sets its approximate voltage at 35kV. 

In order for this voltage to really work, the insulation will have to meet the same current requirements of high-voltage conductors. This is why it is crucial to use only high-quality jumper cables. However, since jumper cables are meant for short-term use, problems with passing a high amount of current through the jumper cable usually do not occur. Overall, to guarantee that the highest amount of current passes through a jumper cable, choose a heavy-duty, large jumper lead. In this way, you will be able to jumpstart your car even when the conditions are far from optimal, such as in the midst of the cold winter or your battery has very low power. 

Which is Positive and Negative on Jumper Cables: Color-Coding

Jumper cables are color-coded so that you would not accidentally reverse the electrical current. Their colors are:

  •  The red cable for the positive terminal is marked with either a "+" symbol or the letters "POS" on the battery.
  • The black cable for the negative terminal is marked with either a "-" symbol or the letters "NEG" on the battery.

Reversing the current when jumpstarting a car using these two cables in an incorrect order can lead to dangerous situations because of the reversed polarity. This can result in battery damage, damage to the car's electrical system, or, in the most severe cases, a risk of a battery explosion. This is due to the fact that there is a rapid surge of current in the event of a reversed polarity.

How to Use Jumper Cables?

When using a jumper cable, it is important to follow the steps without hesitation.

The most important thing to remember is that the red cable goes on first when jumping a car, and the black cable is disconnected first. Here is the step-by-step guide to jumping a car with a jumper cable:

Step 1: Position the Cars

To position the cars, bring two cars, the good car and the dead car, close together but without them touching. At this step, both vehicles should be turned off, with their keys removed.

Step 2: Attach Red to Dead

At this step, you should attach one end of the red positive cable to the dead battery. The correct cable to connect will have the "+" symbol or the letters "POS" on the battery.

Step 3: Attach Red to Good

Now, you should attach the red positive cable to the donor car's battery.

Step 4: Attach Black to Good

Time to attach the black negative cable to the good battery of the donor car.

Step 5: Attach Black to Dead (Surface, not Battery)

At this point, you have to attach a negative cable to the metal surface of a dead car. Instead of attaching the cable to the dead battery, connect the cable to the unpainted, metallic part of the dead car's engine. This will help to ground the circuit and will prevent sparkles from appearing.

Step 6: Start the Donor Car

Start the engine of the good car and let it run for a couple of minutes before proceeding. The recommended time is about three minutes.

Step 7: Start the Dead Car

At this point, try to start the car with the dead battery. If you succeed, leave the cat idle for a few minutes so it charges.

Step 8: Remove Cables in Reverse Order

If your dead battery has started running, it is time to disconnect the jumper cables, starting with the black negative one. When disconnecting, the cables should not be let touch each other or any part of the car.

This is it. Now, drive your jumpstarted car for 15-30 minutes before the battery recharges completely.

Where To Get a High-Quality Booster Cable?

A jumper lead is an emergency cable that people do not use all of the time. That is why many car owners do not have it at hand when they need it. In the United States, you can buy jumper cables at gas stations as a rule, but they tend to be of a smaller size and are not heavy-duty, which might be a problem, especially in case you own a truck or a large car. Therefore, it is better to be safe than sorry and have a high-quality jumper cable of your own ready in the car.  

Nassau National Cable sells single-conductor portable power jumper cables rated at 35 Kv by the manufacturer with EPR insulation and a CPE thermoset jacket that protects the cable from oil and all sorts of mechanical impact.

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What Are Jumper Cables And Their Voltage?