which battery terminal do you disconnect first
Warnings. 1  Always disconnect the negative cable or terminal first when you are working with a car battery. Failure to do so could result in electrical sparks and severe burns. 2  Metal may conduct electricity and cause severe burns.
With the engine off, pop the hood and find the battery. Detach the negative (black) battery cable from the battery. First loosen the nut with a combination wrench. A better tool to use would be battery pliers or a battery wrench. Twist and pull up on the end of the cable with your hand. If it does not come off easily you may want to purchase a battery terminal puller.