by James Dreamer

Created on: August 31, 2010

Nothing draws more power from your vehicle’s battery than starting the engine. In cold weather, the starter may draw over four hundred amps. All the rest of the electrical system doesn’t even come close. Most accessories draw less than twenty amps. And, unlike other devices that can draw power from the alternator when the engine is running, the starter depends totally on the battery for its energy. In other words, if there is any weakness in the battery, it will most likely show itself during the engine starting process.

Jumper cables are used to connect your car’s electrical system to that of another vehicle when your battery is too weak to start the engine. Before we discuss how to use them, let’s decide which cables are best to purchase.

It is important to take into account the large amount of current these cables must transfer between vehicles. There are three main attributes to consider when making your selection. The size of the wire, the length of the wire, and the material from which it is made.

If you have a choice, purchase cables containing the largest gauge wire, remembering that the smaller the number, the larger the wire. Zero gauge is larger than one gauge. Double zero is even larger. Buy the shortest cables that will reach between vehicles. Six or eight foot will carry much more current than twelve or sixteen foot. Wire made from copper is a better conductor than aluminum and will transfer more power. Also, examine the clamps to make sure they will connect easily to your battery.

When you use jumper cables, you are connecting both batteries together to form one large battery. To accomplish this, you must connect the positive to positive and negative to negative. Positive is identified by the color red or the + sign. Negative is identified by the color black or - sign. This is important as connecting the cables incorrectly can damage both batteries, the cables themselves, and possibly other electrical devices. Follow the procedure below to jump start a vehicle.

Place both vehicle ignitions in the OFF position. Gain access to each battery and make sure your cables can reach between them. Clamp one end of the positive (red) cable to the positive battery connection on the car with the good battery. Clamp the other end to the positive of the dead battery. Clamp one end of the negative (black) cable to the negative connection of the good battery. Clamp the last cable end to a solid metal bracket or bolt attached to the engine of the car you are trying to jump start.

It is not recommended to make the final connection directly to, or near, the battery. Batteries produce hydrogen gas which is explosive. When the final connection is made, a spark may occur at the point of contact. If hydrogen is present, it can detonate, causing injury. Always make the last connection away from anything flammable.

When all connections are made, start the dead vehicle, If it does not start right away, start the good vehicle so it can keep both batteries charged. After the dead vehicle starts remove the cables in the reverse order that they were connected. Clean the clamps if necessary to remove any battery chemical contamination and store the cables for future use.

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