A battery cable is an electrical wire connected to your vehicle’s battery. There are two cables, positive and negative, each quite large, that allow power to be transmitted from and to the battery.
The 12-volt battery in your vehicle allows all of the electrical operations to function when the engine is off. More importantly, it provides the power needed to start your engine. Once the engine is running, the battery hands off the responsibility for electrical function to the alternator. The alternator, in turn, recharges the battery, while the battery lends a hand to buffer any voltage spikes that might occur.
The positive battery cable connects the positive terminal of the battery to the starter on the engine and to the vehicle’s computers and other electric/electronic devices by way of a network of wires. The negative cable is attached to the chassis, thus providing a universal ground for the whole vehicle. In this way, a closed circuit is enabled between the battery and all of the electrical components of the vehicle.
At the end of each battery cable, where it attaches to the battery, is a connector called a battery terminal. Terminals can attach to a battery in one of several ways, depending on the vehicle make and model. For instance, some batteries feature two posts on top that are made of lead. The battery cables, or the terminals at the ends of the cables, clamp over their respective posts. Other batteries come with recessed female connectors on the sides. The “side-post” batteries require that a different type of terminal be screwed into each connector.
One reason that a battery cable might need to be replaced is if the terminal at the end is damaged. This can happen due to improper tightening or corrosion. A battery cable might also need to be replaced if it becomes damaged, cracked, or corroded (rusted).
The signs of a bad battery terminal include the following:
The procedure to replace a battery cable depends on the specific vehicle make and model, where the battery is located (most are mounted in the engine compartment, but some are remotely placed in the trunk, fender well, or other location), and which cable is in need of replacement.
The negative cable is relatively simple to access in most vehicles, since it mounts directly to the vehicle’s chassis or frame. The positive cable is a bit more complex.
To replace either one, the negative cable is first removed from the battery to disconnect the electrical circuit to the vehicle. It might also be necessary to disconnect the positive cable and remove the battery. If the positive cable is to be replaced, the technician will trace its path to its origin, which might be at the starter on some vehicles or in the fuse/relay block in others. The cable end is detached, the new cable is inserted in its place, fastened, and routed along the same path.
Once the new cable has been installed, the battery is put back in place and cleaned. Then both cables are attached to the battery, starting with the positive terminal. Finally, the technician will power up your vehicle to make sure the repair is complete.