Dead battery

A battery without enough electrical charge to run engine components is considered dead. However, this does not necessarily mean that it is permanently damaged or defective. As the engine runs, the battery is recharged by the alternator. The cause of a dead battery could be the result of a defect in the charging system or the result of leaving an accessory such as headlights on without the engine running.

Table of Contents

• 1. Causes
  • 1.1 Alternator Not Charging
  • 1.2 Accessory Left On
• 2. Symptoms
  • 2.1 Engine will not start

Causes

Alternator Not Charging

There are many reasons why the alternator may not be charging the battery. The belt that turns the alternator may be disconnected. The wires that lead from the alternator to the battery may be damaged or disconnected. The alternator may be defective.

See Alternator not charging.

Accessory Left On

The car battery acts as the vehicle's electricity source. As the engine runs, power is drawn from the battery to run the accessories like radio or headlights. The alternator uses the rotation of the engine to recharge the battery. When the engine is off, the battery is not replenished. If left on for too long, the battery will run out of power and may require a jump start.

Symptoms

Engine will not start

If the engine will not start, but there are still some sounds from the engine like clicking, the battery has some power, but not enough for the starter motor to turn the crank shaft.

If there are no interior lights, dashboard lights and chimes, or sounds coming from the engine when the key is turned, the battery may be completely out of power.

A jump start can give a temporary boost of power to the battery. It is recommend to leave the vehicle running after a jump start so the alternator can recharge the battery.

If, after a jump start, the battery is dead again, there may be a problem with the alternator or charging system.