Consider these failing car battery warning signs:
- The car horn sounds much weaker than you ever remember it sounding.
- When you try to start the car in the morning, the engine is turning over very slowly.
- The headlights appear to be very dim when the car turns over.
- There is a very strange odor coming from the battery compartment.
- When the car is running, the interior lights keep flickering.
- The casing around your car battery is swollen.
- The check-engine light stays lit while driving.