When disconnecting the cables from the old battery, disconnect the negative first, then the positive. Connect the new battery in the reverse order, positive then negative.” When you are replacing your car battery, It isn't always easy to remember the order in which to disconnect and reconnect the terminals.

Why do you disconnect the negative first?

The negative () cable is the ground cable; it is always connected to the frame or body metal and can safely be disconnected first with no chance of causing sparks. By the same token, always reconnect the positive cable before connecting the negative cable.

Do you take off negative first?

Always work on the negative terminal before the positive when you disconnect your battery. ... Push it aside so it is unable to make contact with the battery while you're doing your work. If the cable is seized to the battery post, a special battery cable removal tool may be needed to remove the negative connector.