What Size Jumper Cables Should I Carry?

Jumper Cables

It can be annoying to try to start the car in the morning only to find that the battery is dead.

On closer inspection you will find that you have left the headlights on or the alternator is defective. Jumper cables are very useful in such situations. All you need to do is find someone with a good car battery and connect one end of the jump leads to your car battery and the other end to the borrowed battery.

The car will come back to life as soon as you start it and your alternator will do the rest; it will charge your dead battery.

Things to consider when buying jumper cables

What Size Of Jump Cables

Finding the right jumper cables can be a challenge. There are those that are too short or made of inferior materials that cannot conduct electricity properly.

The jumper cables size should match the size of the vehicle you are going to start. 4- or 6-gauge cables work for the most mid-sized cars, but cars with bigger engines like trucks may require 1- or 2-gauge cables. But also the length and the clamps matters.

Remember that it is better to have thicker cables than the vehicle requires than thinner.

In this article, we will show you some key factors to consider before buying a set of jumper cables.

1. Length

Most jumper cables on the market measure 10 feet. This is ideal for saloon cars, but if you have a larger car, look at the 20 to 25-foot jumper cables. This allows you to connect the two batteries together without stretching.

2. Rating

This is one of the most critical factors in the search for jumper cables. If you have cables of the wrong thickness, less current will be conducted and your car will not start. Most cables for SUVs and saloon cars have a gauge of 4 to 6, for large trucks a gauge of 1 to 2 is sufficient.

3. Material composition

Jumper cables should be made of conductive materials. The best materials are copper rather than aluminum. Copper is a good conductor, but it is expensive, so some people prefer cheaper aluminum cables. However, aluminum cables are not so good for heavy trucks. There is a compromise where copper cables are sheathed in aluminum.

4. Clamps

These grip the battery poles and are crucial for the transmission of current between the batteries. They are designed to connect to each other. The most common type of clamps are crocodile clamps.

These have sharp, pointed teeth that firmly surround the battery poles. Look for jumper cables that have some form of insulation around the clamps. This will help prevent accidental shock. Heavy rubber is often used for insulation. Before you start the car, make sure that the positive and negative terminals are well connected.

5. Tangling

Jump Cables

The material used to make the jumper cables should be strong enough to resist tangling. It can be annoying to struggle to untangle the jumper cables in an emergency. They should also be easy to store. After purchase, the jumper cables should be stored in a special box so that they are not destroyed by weather conditions.

Too much sunlight destroys the insulation of the cables, and this can cause shocks, while moisture can reduce the conductivity of the terminals.

We always recommend using a jump starter instead of jumper cables. A jump starter has reverse polarity protection inside, which makes it much easier to use, and you can store it in the glove compartment! Have a look at our article: Best Jump Starters to buy.

Why does a car’s battery go flat?

If you have had to deal with dim lights and problems starting your car in the morning, you need to look at the following reasons. Jumper cables are a stopgap solution, but you must get to the root of the problem if you don’t want the problem to continue.

Defective Alternator

The alternator is used to charge the car battery and to supply certain electrical devices such as air conditioning, electric windows or radio. If the alternator malfunctions due to problems with the diodes or the stator, the car battery will not charge fully.

The charge level is often so low that the car cannot be started, so jumper cables are required. If you do not repair the alternator, the problem will persist.

Human error

This is the case if you have an old car. There are moments when you come home exhausted and forget to turn off the headlights or leave one of the doors open. Your battery will discharge overnight and you will need to use jumper cables to jump-start your car.

As soon as the car starts, the alternator charges your battery and that’s the end of the problem. Modern cars have warning signals if you leave your headlights on or a door unlocked.

Extreme temperatures

When you leave an area where extreme temperatures prevail (either hot or cold), it is common for lead sulfate crystals to accumulate around the battery. This makes it difficult to fully charge the car battery, especially for short trips. Over time, the lead sulfate crystals will destroy the car battery.

Loose battery cables

There are moments when the battery will not start because the battery terminals are loose. You will notice flashing lights on the dashboard. The solution is to get a ratchet or a screwdriver and retighten the screws. You don’t need jumper cables for this because your battery is still fully charged.

You could pour over some Coca-Cola soda or other carbonate to clean metal deposits from your connections.

Old battery

If you have been using the same battery for many years, its life may have expired. The alternator may work well, but it will recharge an empty battery. You can check the battery for its voltage performance and, if it is weak, buy a new one.

A good battery should last more than four years, but this depends on use and brand. Check the manufacturer’s manual to see how long the battery should last.

If you want to buy a new battery, read our overview of the best car batteries.


Jumper cables always serve as lifesavers when your battery is empty. All you need to do is connect one end of your jumper cables to your dead battery and the other end to a fully charged battery. As soon as you start the car, the alternator will start charging the dead battery.

It is recommended that you drive a long distance to ensure that the battery is fully charged before you turn off the ignition. There are several reasons for a dead battery, including a malfunction of the alternator, extreme temperatures, human error such as turning on the headlights, and a battery that has served its purpose.

Make sure you choose well-insulated jumper cables with the correct ratings, otherwise you may short circuit your circuits. Choose jumper cables that are long enough to ensure a smooth connection.

If you have further questions about jumper cables, please leave a comment below!

Written by: Magnus Sellén

Founder, owner & main author of Mechanic Base. I have been repairing cars for more than 10 years, specialized in advanced diagnostics & troubleshooting. I have also been a drifting driver and mechanic for over 7 years.