Chances are, if you have not been faced with a car that won't start, you know someone who has. There are several reasons a car will not start, but a dead battery is one of the cheaper and easier problems to fix. It is not always easy for a lay person to tell the difference between a dead battery and a more serious problem, but there are certain symptoms that help make diagnosis easier.
No Keyless Entry or Alarm
The battery provides power to every function in the car--this includes the keyless entry and alarm system. If your doors do not unlock with the remote, or if the panic button does not work, it is possible that your car battery is dead. In other cases, the doors may unlock but the lights will not flash and the horn will not sound.
No Lights or Chimes
If you open the door and the dome light does not come on, or if you leave the door open, put the key in the ignition and the chimes do not sound, chances are your battery is dead. You can also try the hazard lights, parking lights and headlights or the windshield wipers.
Clicking Sound on Ignition
If you turn the key and hear a clicking sound, your battery is most likely dead. Also, if you turn the ignition switch to "On," the "Battery" and "Check Engine" lights will either be very dim or will not come on at all.
Headlights Set to "On" Position
If your headlight switch is on when you get into the car, it is possible that the lights were left on for several hours, which discharged the battery. A dome light left on or a device plugged into the accessory jack, for several hours--or days--while the engine is off, will also discharge the battery.
Car Battery More Than Three Years Old
Car batteries only last three to five years. If your car battery is older than that, it is probably time to replace it--even if it appears to be working fine. An older battery can work one moment then be dead the next--and usually at the worst possible time.
Battery Will Not Hold a Charge
You may recharge the battery, only to have it die again. You may notice that the lights dim or the horn does not work while driving. The alternator should charge the battery during normal vehicle operation. When you are using many of the accessories at the same time--lights, wipers, heating fan, wipers--for example, on a snowy night, the battery power should combine with the alternator to keep everything functioning. If it does not, the battery may be too old and may need replacement. If the battery is newer, it may be that it is not installed properly or the alternator is failing.