If a battery won’t hold its charge because it’s old or broken, replace it. However, if your battery is “dead” because you left your lights on, you should be able to jump-start it and charge it back up again to its full capacity (by running it for a half-hour or so).

As with all things automotive there is always the possibility of spewing corrosive acid, hydrogen fireballs and really impressive explosions. These general instructions are for a 12-volt, negative-ground battery; if you don’t know what that means, call a tow truck. If you do decide to try it yourself, remember that this is not meant to foresee every possibility, and that any time you’re working with chemicals, electricity and machinery there is the risk of injury, property damage or death.

Still, it’s a fairly straightforward procedure and a good thing to know.

1. Make sure that both your battery and the “donor” battery are the same voltage.
2. Don’t try to jump a battery that’s been damaged. Check to see that the caps are level and closed, and that there are no cracks or leaks.
3. Make sure the two cars are not touching.
4. Both cars should be in neutral or park, the parking brakes should be set, and the ignitions turned off.
5. Check the owner’s manual for directions specific to your vehicle.

Take a look at your jumper cables. Red stands for Positive and Black stands for Negative; once you’ve begun to hook the cables to the batteries, DON’T LET THE RED CLIPS TOUCH THE BLACK CLIPS. When you connect them to the battery terminal posts, open the clips wide so they’ll attach firmly.

The trick to proper jump-starting is the sequence in which you attach the jumper cables. Connect them in this order:

1. One Red (positive or +) clamp to the Positive (+) battery terminal post on the DEAD battery
2. The other Red (+) clamp to the Positive (+) battery terminal post on the GOOD battery
3. One Black (negative or -) clamp to the Negative (-) battery terminal post on the GOOD battery
4. The other Black (-) clamp to the frame of the car with the DEAD battery (NOT THE NEGATIVE BATTERY TERMINAL)

Once everyone has stood well back and you’re sure nobody has his necktie hanging in a fan belt, start the car with the good battery and let it run for a minute or so. Now try to start the car with the dead battery. If you’re lucky it will start right up; if not, make sure ALL accessories (lights, radio, dome light, etc.) are off and try again a few times. This will probably do it. If not, you probably have other problems; call AAA.

If it DOES start, then just let it run as you CAREFULLY disconnect the jumper cables IN THE REVERSE ORDER IN WHICH YOU ATTACHED THEM. As always, be careful as you move around a running car’s engine compartment; don’t drop the jumper cables into the motor or get your lips stuck in the flywheel.

Slam the hood, thank the Good Samaritan who stopped to help you out, and remember to turn off your lights the next time!