Two cars, one (dead) battery

The cables

First connection

Negative terminal

One more positive connection

Engine block ground

All connected

Fire it up

If your car won't start because you left your lights on overnight or spent too much time listening to music while parked, you may need a jump-start. We're going to show you how.

You'll need your disabled vehicle and a donor vehicle with a charged battery.
Caption by / Photo by Antuan Goodwin/CNET
Of course, you'll also need a set of jumper cables. Note that the jumper cables feature color-coded clamps at each end. Red is for positive terminals and black is for negative and ground. A basic set of jumpers should run about $20 and is a must-have for every driver's roadside safety kit.
Caption by / Photo by Antuan Goodwin/CNET
Make sure both vehicles are parked with their engines stopped. Pop the hood of the live car and connect the jumper cables, starting with the red connection to the positive battery terminal. Usually this will also be marked with a red cap. If not, look for a "+" mark.
Caption by / Photo by Antuan Goodwin/CNET
Next, connect the black clamp to the live battery's negative terminal.
Caption by / Photo by Antuan Goodwin/CNET
Moving over to the disabled vehicle, connect the red clamp at other end of the jumper cables to the dead battery's positive terminal.
Caption by / Photo by Antuan Goodwin/CNET
Do not connect the black clamp to the dead battery's negative terminal. Instead, connect it to a grounding point on the engine block or the vehicle's chassis. There's usually an easily accessible tab on the front of the engine block that works great for this purpose.
Caption by / Photo by Antuan Goodwin/CNET
The disabled vehicle's engine bay should now look like this photos, with one lead connected to the positive battery terminal and another connected to the engine block ground.
Caption by / Photo by Antuan Goodwin/CNET
Fire up the engine of the healthy car, let it run for about 30-60 seconds, and then attempt to start the disabled vehicle's engine. If it turns over, remove the jumper cable connections, starting with the engine block ground. If not, you may have a bigger problem than a simple discharged battery.
Caption by / Photo by Antuan Goodwin/CNET
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