How to Use Jumper Cables
Learn how to bring your car back from the dead without hurting yourself or it
At any given moment in America there are countless people in parking lots and driveways with dead batteries, jumper cables, and at least a little hesitation about how to use the latter without blowing up a battery.
An explosion of that sort is a legitimate concern when jumpstarting a car. It can send battery acid and battery fragments straight into your eyes, according to the University of Rochester Medical Center. In fact, using jumper cables wrong causes thousands of Americans to suffer serious eye injury or lose their eyesight each year according to the occupational safety and health experts at University of Wisconsin.
“Not following the jumpstart procedure can cause a personal injury and vehicle damage,” says Brian Guerro, pacesetter roadside assistance general manager at AAA Colorado.
Here's the right way to use jumper cables.
Before you start
First make sure the battery really is the problem. “Check to see if any lights have been left on or turn on the headlights to see if they even come on. If not, the battery is dead or weak,” says Guerro. Another indicator: The car cranks slowly or makes a clicking sound when you turn the ignition key.
If the battery is indeed dead, call someone with a car to give you a jump. They can't drive a hybrid or electric car. Both vehicles need to have 12V battery systems.
While you wait, check your vehicle’s owner manual for any specific cautions regarding your car, advises Guerro. It's also a good idea to inspect your jumper cables for visible wires, corrosion or other signs of damage. If you spot any, don't use the cables.
Have the driver park so that his battery is as close as possible to yours — the cars should be close but not should not touch. Remove any jewelry (long necklaces, dangly bracelets) that could make contact with the battery or get caught in moving parts under the hood. If you have goggles and work gloves, wear them.
Disconnect accessories such as cell phone chargers and GPS units in both cars. Remove the keys from each ignition.
Battery jumping step by step
Now follow these steps from Guerro, AAA Colorado and the American Academy of Ophthalmology.
Step 1. Identify the batteries’ positive (+) or negative (-) posts. If the battery terminals are dirty, brush them or wipe them off with an old cloth.
Step 2. When holding the jumper cables, do no let the clamps touch each other. Connect the positive cable, often red or orange, to the positive terminal of the dead battery. Then connect the other end of that cable to the positive terminal of the good battery. Remember, "positive to positive, negative to negative."
Step 3. Connect the negative cable, which should be black, to the negative terminal of the good battery. Then connect the other end of that cable to a ground on the engine of the disabled vehicle, as far away from the battery as possible. A ground is a metallic, unpainted part of the engine or frame. A large bolt should do nicely. “This is done for safety purposes to prevent a potential explosion of the battery in case battery gases or sparks were created during connection,” says Guerro.
Step 4. Start the car with the good battery and wait a few minutes.
Step 5. Start the disabled vehicle. Once it’s running, remove the jumper cables in reverse order of how you installed them. When removing each clamp, take care that it does not touch any other metal while the other end is still attached.
After you successfully jump your car, head straight to the mechanic. “A certified technician will look at the age of the battery, the condition of the terminals and cables, and will run a test to identify any issues and make the appropriate adjustments or repair,” says Guerro.
The right jumper
When buying jumper cables, pick up the right ones. “They should be at least 300 amp rated, 8 gauge thick and 12 feet long,” says Guerro. Jumper cables also should be color-coded and tangle-free for easy handling and have a cold weather jacket rated down to at least -20°F, he adds.
If you're on the road a lot, Guerro recommends buying a rechargeable jump-start pack in addition to your jumper cables. “The jump-start pack will start the vehicle without needing a secondary vehicle and can be used as a power source for charging a cell phone,” says Guerro.
Related: Road Trip Checklist for Your Car
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