How to jump-start a car

We've all been there at least once: you've left your headlights on and when you go to start 'er up, you get nothing. What you need is a jump start.

Jump starting a car with a dead battery is easy and safe if you make the right connections.
Jump starting a car with a dead battery is easy and safe if you make the right connections. Antuan Goodwin/CNET

We've all been there at least once: you've left your headlights on overnight or spent too much time listening to music in your car and when you go to start 'er up, you get nothing. What you need is a jump-start. So, call a friend or flag down a neighbor, because I'm going to show you how to do it.

What you'll need:

  • your disabled car with a drained battery
  • a donor car with a charged battery
  • jumper cables
  • insulating gloves (optional)
  • eye protection (optional)

Step 1: Note the orientation of the cars' batteries in the engine bays. Position the vehicles' to get the two batteries as close together as possible to allow room to work and for the jumper cable to reach. Shut down both engines to avoid damage to the electrical systems.

Step 2: Grab one end of your jumper cables. Note the terminal posts on the donor car's battery and connect the negative clamp (black) to the battery's negative terminal (also black) and the positive clamp (red) to the positive terminal (also red). Black to black, red to red. That's the easy part.

Step 3: Grab the other end of your jumper cables, being careful to avoid touching the exposed teeth of the other end of the cables and to avoid touching these now electrified clamps to each other. Connect the positive clamp (red) to the positive terminal of the dead battery (also red), but don't connect the negative clamp to the negative terminal. That can change the voltage of the circuit you're creating with the cables and cause all sorts of electrical issues, from blown fuses to (on rare occasions) exploding batteries. You're starting to rethink that eye protection now, huh?

Step 4: Instead, take the remaining negative clamp and connect it to the dead vehicle's engine block. Most engines have a metal tab sticking out somewhere near the front that's perfect for this, but any exposed metal on the engine block or the vehicle's body will usually do.

Step 5: Double check your connections, then start the donor vehicle to begin the charging process. Allow the donor vehicle to run for about 30 to 60 seconds.

Step 6: Attempt to start the disabled vehicle. If it starts, immediately remove the negative cable attached to the now undead car's engine block first, then remove the rest of the connections. You may allow the revived car to idle for a minute to give the battery a good charge, but the ride home should be more than enough to get you juiced back up.

Once you're running again, do a quick search to figure out what drained your battery in the first place. Did you leave your lights on? Is an aftermarket amplifier connected improperly? Most stock car batteries are not designed for multiple deep drains, and getting jump started too often can leave you with a battery that can no longer hold a charge or accept a jump, requiring replacement.

In the event that the dead car does not start after about 30 to 60 seconds of cranking, it probably won't at all. Thank the good Samaritan who's been helping you and call a tow truck.

Intelligent jumper cables like these Michelin Smart Jumpers feature built-in electronics that not only let you know that everything is correctly connected, they'll also correct polarity issues, so you won't have to keep track of what's positive or negative. They also feature surge protection to prevent sparking or damage to either vehicle's electrical systems. And if you don't want to be stuck looking for a donor vehicle in an emergency, try keeping a portable jump starter in your vehicle's trunk. These little rechargeable lifesavers supply just enough juice to get you going in an emergency, filling in for the roll of donor vehicle. Just start this How To at Step 3, if you decide to use this method.

 

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