If the battery won't start your car, you usually refer to it as "dead," even though that's not technically correct. A car battery that's merely discharged - from leaving your headlights on or from a damaged alternator -- can be recharged to its full capacity. But a battery that's at the end of its service life can't be recharged enough to restore it to a useful power level. Then it truly is dead, and must be replaced.

If the battery is discharged but not dead you can jump-start it from another fully charged battery. About 30 minutes of driving should allow the alternator to charge the battery until you can get it to a service station for a full charge. However, if the alternator or another part of the electrical system in your car is damaged it won’t be possible to to recharge your battery. So if your battery keeps discharging, first have your electrical system checked. What looks like a bad battery could be an electrical system problem; if you have a bad component in the electrical system, it will keep draining a new battery, and you'll be stranded again and again.

Click here to learn how to jump start a car battery

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