The battery of the car is meant to provide enough power in order for the engine to start. It is also supposed to deliver an electric current to devices and lights in the car and it charges from the alternator when the car is running. The battery is also a back-up source of energy from the engine and the accessories in case the alternator dies. The cables of the battery might be damaged in time especially if you do not pay any attention to them. If they are seriously damaged, they need to be replaced with new ones. Here is how to do this on your own:

Find the negative terminal of the battery and use a wrench to disconnect the negative cable from it. Use the wrench in a counterclockwise direct for unscrewing the nut that keeps the cable on the terminal. The negative terminal is usually marked with a “-.”

Identify the positive terminal of the battery by the “+” symbol and disconnect the positive cable from it in the same manner with the wrench.

Follow the positive cable to the starter solenoid that is typically located on the right side of the car.

Once you find the solenoid, remove the cable from it. You will notice that it slides into a post on the solenoid and it is protected by a nut. Unscrew the nut by using the wrench in a counter clockwise route and holding the cable. Put it aside from the solenoid.

Take the new positive cable and place its end of the starter solenoid. Use the nut to secure it in place and then tighten it by using the wrench in a clockwise direction.

Find the ground point of the negative cable, which is usually on the side of the engine.

There should be a bolt in the end of the earth wire, so loosen it with a wrench in a counterclockwise direction and take the cable out.

Take the new negative cable and secure it back in the place of the old one using the bolt you have just removed. Tighten the bolt using a wrench.

Connect the positive cable to the positive terminal of the battery. You need to slide the cable over the terminal, to secure it with the bolt and to tighten the bolt with a wrench in a clockwise direction.
Do the same thing for connecting the negative cable to the negative terminal of the battery. Slide it over the terminal, secure it with the bolt, and then use the wrench in a clockwise direction to tighten it.