Here are the connection steps:
- Be sure both ignition switches are in the OFF position.
- Locate the "+" (positive) and "-" (negative) sides of each battery. They should be clearly marked on the battery itself. On newer cars the positive (+) side often has a red cover over the battery post and wires.
- Attache the red cable to the "+" side of the good battery
- Attach the other end of the red cable to the "+" side of the dead battery
- Attach the black cable to the "-" side of the good battery
- Attach the other end of the black cable to a section of unpainted metal on the dead car. This can be as small as the head of a bolt located nearby.
*Attach the jumper cable to the most secure attachment point you can find on the car's permanent battery cables. If they are corroded, it may help to wiggle the jumper cable end around a bit while it's attached to the car's cables or battery.
*You might be tempted to attach it to the "-" side of the dead battery, but this isn't recommended. In the old days, batteries leaked small amounts of acid, which could turn into flammable gas around the battery. This gas could explode if the cable caused a spark just above the battery.
*I have seen some people clamp the negative cable onto the rubber cable covering of the positive side while they walk across to the other car. This is a NO NO. If one of those sharp teeth were to pierce the rubber cover and reach the wires inside, you could do serious electrical damage to one or both vehicles!