When jump starting a battery, which connection is correct?

• A. Negative terminal of the good battery to the positive terminal of the dead battery
• B. Positive terminal of the good battery to the negative terminal of the dead battery
• C. Negative terminal of the good battery to the negative terminal of the dead battery
• D. Positive terminal of the good battery to the positive terminal of the dead battery

Answer: (D)

When jump-starting, you need to form a complete electrical circuit from the charged battery to the dead one with correct polarity. The best first step is to connect the positive terminal of the good battery to the positive terminal of the dead battery. This creates a proper path for current to flow into the dead battery, starting the charging process and allowing the dead vehicle to turn over once enough charge is restored. After that, connect the negative terminal of the good battery to a solid grounded metal surface on the dead vehicle (such as the engine block or chassis), not to the dead battery’s negative terminal, to minimize sparks near the battery. Sparks near a battery can ignite hydrogen gas and cause an explosion. Start the donor car, then the dead car, and remove cables in reverse order.

This positive-to-positive connection is the essential first step because it establishes the correct route for current to enter the dead battery. Connecting negative to negative or cross-polarity would not provide the proper return path and could cause sparking, damage, or fail to start.