To jump start a vehicle with a discharged battery, park the booster vehicle close to the one that needs a little charge. However, make sure that the vehicles are not touching in any way. Also, make sure that you would be using a good set of jumper cables, thick wires, and clean clamps. When hooking the jumper cables, make sure that the cables do not dangle into the engine compartment. Turn off the ignition of both vehicles. Put on the parking brakes. For automatic transmission vehicles, set on "Park". For manual ones, set on "Neutral". Make sure that all other things are turned off like lights, radio, flashers, etc.

Clamp one end of the positive jumper cables to the positive battery terminal. The positive cables are colored red. The positive on the battery are those with a "+" on it. Make sure that the clamp is secure. Also, check if the terminals are corroded. If they are, you have to scrape them first with abrasive. Then, connective the negative cable (this is colored black) to the negative battery terminal. The negative terminal is that with a "-" marked on it. Then, the other end of the negative cable should be attached to an unpainted metal surface of the dead car. However, make sure that it would be attached somewhere far from the dead battery as possible.

Confirm if the jumper cables are not near any moving parts of the engine. Then, start the booster car. Let it idle first for a couple of minutes. If the dead battery is new and got drained because the lights were left on for a long period of time, chances are that it could start immediately. On the other hand, an old battery which has been torpid for a long time would take some time to charge. Then, start the dead vehicle and let both vehicles idle for a couple of minutes more. There are instances though that the dead vehicle would refuse to start. If this happens, do not keep on trying. Doing so could damage the starter.

If you have successfully made the vehicle start and run okay, disconnect the jumper cables. However, make sure that you do it in reverse. Be careful in disconnecting them. Do not let the dangle cables fall into the engine compartments and do not let them touch each other.