How to Jump Your Battery
A battery has a negative (-) terminal and positive (+) terminal. Each terminal will be labeled with the appropriate symbol and most wires will be color coded—red (or yellow) for positive (+), black for negative (-). On top post batteries, the positive (+) post is larger than the negative (-) post. Always pay close attention to the color of the cables and the negative (-) and positive (+) symbols on the battery or post, and be aware the order in which you connect the cables to the batteries does matter, so make sure you follow the correct sequence to avoid the discharged battery exploding and potentially causing injury, death or disfigurement.
Bring it to the disabled vehicle.
Car batteries are usually twelve Volts. Trucks/tractors may operate on a twenty-four volt system, sometimes two twelve volt batteries combined to make a twenty-four volt system. Do not attach 12V to 24V.
Make sure the cars are not touching.
Open the hood of each of the cars.
Unplug anything charging in the cigarette lighter. They waste power and might even be damaged by surges of power.
The jaws of the cable clamps are designed to bite into the soft metal of the battery clamps that are attached to the battery terminal posts.
If any of these exist, stop. Call a tow truck, do not attempt to jump the car, do not even connect the cables.
Then connect the other end with the red clamp to the positive (+) post on the good battery.
Remember, the order in which you attach the clams does matter, so follow these steps exactly.
Do not connect this clamp to the negative post of the dead battery—do this only as a last resort. (See tips for suggestions on what metal parts to clamp to.)
It will charge its own battery and the dead one.
Never race the engine. If a "fast" idle is not enough to charge the dead battery then it's not going to charge.
If it doesn't start, wait another five minutes for a little more charging, and try again. Repeat until the disabled vehicle starts.
Remove the clamp from the ground of the recently disabled vehicle, black and red from the good battery and finally the red from the formerly dead battery.