Determine a car battery polarity when you jump a car by checking a battery's positive and negative terminals and learn how with expert tips in this free car-maintenance video.
We're going to determine the battery's polarity. Each battery is equipped with a positive and negative terminal. They should be clearly marked on the battery. Quite frequently the positive terminal is shielded or coated or protected by a red covering and the negative terminal by a black one. If these aren't present or you can't see the markings on the battery, you can look at both terminals. The positive terminal is always larger than the negative terminal. That's a quick and easy way to identify which one is which. On side post battery's, they should be clearly marked and the cables once again will be either red or black; red indicating positive, the black indicating negative. These are both the same size on the side post and you can't determine them by size. But your standard top post battery, the positive terminal is always the larger of the two terminals. Watch the next segment on connecting the vehicles.