A battery has a negative terminal and positive terminal. Each terminal will be labeled with a symbol. A plus sign (+) indicates positive, and a minus sign (-) indicates negative. On a top-post battery, the posts are located on the top of the battery, and the positive post is larger than the negative post. On most vehicles, the installed battery cables are red and black. Red is (+) positive; black is (-) negative. On a side-post battery, the posts are located on the side of the battery. Always observe the color of the cables and the negative and positive symbols.
Step 1
Get a working vehicle. Bring it to the disabled vehicle.
Step 2
Verify that both the dead battery and the rescue battery have the "same" voltage. 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.
Step 3
Position the vehicles so that the car batteries are close enough to each other for your jumper cables to reach each one. Make sure the cars are not touching.
Step 4
Turn off both engines. Open the hood of each of the cars.
Step 5
Turn off the headlights, wipers, radios, and all accessories on both cars. Unplug anything charging in the cigarette lighter. They waste power and might even be damaged by surges of power.
Step 6
Untangle and unwind the jumper cables. 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. Don't attach neg. to pos. so do not attach in " series." That may damage the electronics.
Step 7
Use safety: if goggles or gloves are available, put them on now. Have anyone not wearing safety equipment stand clear of both vehicles.
Step 8
Visually check both batteries for cracks, leaks, and damage. If any of these exist, STOP. Call a tow truck, do not attempt to jump the car, do not even connect the cables.
Step 9
Connect a red clamp "first" to the (+) positive post on the dead battery. Then connect the other end with the red clamp to the (+) positive post on the good battery.
Step 10
Connect a black clamp to the (-) negative post of the good battery.
Step 11
Connect the only remaining clamp (a black clamp for the dead battery) to a solid piece of grounded metal (best if it is clean and non-painted) on the dead car. Avoid connecting this clamp to the negative post of the dead battery--do this only as a last resort. (See tips for suggestions on what to clamp to)
Step 12
Start the working vehicle so it can be charging its own battery and the dead one.
Step 13
Let it idle for approx. 5 minutes before trying to start the other car. Never race the engine. If a "fast" idle is not enough to charge the dead battery then it's not going to charge.
Step 14
Try to start the disabled vehicle. If it doesn't start, wait another five minutes for a little more charging, and try again. Repeat until the disabled vehicle starts.
Step 15
Remove the jumper cables from the vehicles in the reverse order from when you attached them (so remove one clamp from the ground of the recently disabled vehicle, etc.).
Step 16
Keep the recently disabled vehicle's engine running a little above idle for at least at least twenty minutes to charge the battery.
Tips
- 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.
- Don't connect the black leads first and the red leads afterwards: if you would do that and accidentally drop the red cable onto the car's frame, a massive short-circuit will form, possibly welding the clamp to the chassis.
- It may be necessary to remove the disabled automobile's battery cables from the battery terminals and clean both cables and terminals. Use a stiff wire brush to remove all corrosion. Reconnect the cables to the battery terminals and jump the car.
- Do not use cheap jumping cables with thin wire. Use good heavy-duty jumping cables.
- Don't let the working vehicle leave for at least ten minutes. The dead battery must charge for a while, and sometimes will go dead again (especially if you do not keep the engine above idle).
- Remember that batteries are not always in the same place. Some vehicles have the battery under the hood, some behind the cab, and some are even in the trunk.
- Look at your jumper cables. Many will have instructions with pictures explaining the order to attach the clamps.
Warnings
- Never cross the cables while attached to a car battery.
- Make sure you are connected to the right posts.
- A charging or discharging battery creates hydrogen gas, which under the right circumstances will cause the battery to explode. This is why one must avoid connecting two batteries directly to one another (all four clamps on battery posts). Use this as a last resort when the primary method fails and you have taken proper safety precautions. Make sure you stand clear. There may be sparks which can cause an explosion.
- Keep your face as far away from the batteries as you can at all times.
- Tell people to back off. Batteries can explode if you don't do the job right.
- Always protect your eyes with goggles or other protection.
- If the alternator in the working car is either worn or very small, there's a small chance it will break during this operation.
