When your car won't start, it may demonstrate dead battery symptoms that can be frustrating and confusing. The following information explains the most common dead battery symptoms:
Engine Will Not Crank--or It Cranks Very Slowly
Two things must happen for a car's engine to start and run: 1) it has to crank quickly enough; 2) it has to fire (or "turn over"). Normally, when you turn the ignition key, the battery supplies the power to the starter to crank the engine quickly for a few seconds until it fires (once the engine has successfully fired/turned over, it runs at "idle" speed until you try to move the car).
If your engine will not crank at all when you turn the ignition key, or if it cranks very slowly, then the battery may need a charge. The "jump-start" is one quick method of charging the battery; however, a severely dead battery will probably require a longer "trickle" charge instead.
Vehicle Has No (or Low) Accessory Power:
If you cannot turn on the headlights, interior lights or radio, then your vehicle does not have accessory power. However, if the lights (dashboard/headlamps/interior) do come on but appear dim, then the battery may not be completely dead--but it probably won't have adequate power to crank the engine quickly enough for it to fire. When your vehicle has no accessory power, then the battery should be charged under either of the two methods described above.
On the other hand, if you do have full accessory power, but the engine will not crank, then there could be other electrical problems: a bad ignition switch, a failed starter/starter solenoid, or a poor electrical connection somewhere in the ignition system. These more advanced electrical problems should be properly diagnosed by a licensed mechanic.
Whenever a vehicle has experienced a dead battery, an electrical check should be performed as soon as possible to determine the condition of the battery and the alternator (which normally charges the battery), and also to check for any draws on the electrical system that may have initially drained the battery.