What are the symptoms of a car battery not holding a charge?

[VanJack]

Here are the symptoms of a car battery not holding a charge: 1. Difficulty starting the car - if the car suddenly has trouble starting without other factors, it may be a sign that the battery is about to fail. 2. Dimming lights at idle - for example, when waiting at a red light or temporarily parked, the headlights may suddenly dim due to reduced charging power from the engine at idle. 3. Battery warning light illuminated - when the battery warning light comes on, it alerts the owner to have the battery inspected and repaired at a service center. 4. Abnormal noises during startup - as the battery's discharge capacity weakens, the starter may operate poorly and produce squeaking sounds, which is particularly noticeable in cold temperatures. 5. Battery inspection window - maintenance-free batteries have an inspection window; the light in the window indicates whether the battery is functioning properly (green means good, black means the battery needs replacement).