Everything about Driving a Car.

When looking for a good ground for that last clamp, look for shiny metal around or on the engine. Painted, oily, or rusted metal will not work. Nuts, bolts, or other protruding shiny metal is best. There may be some sparking when you connect to a good ground. It's strongly recommended not to clip the last clamp to the dead battery (which would be an obvious choice) as the sparks that may fly when you complete the electrical circuit could ignite the hydrogen gas coming off the battery.
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