To determine whether a car battery needs replacement, multiple indicators should be considered comprehensively. First, observe the starting performance: if the engine cranks slowly during ignition, is accompanied by a "clicking" noise, or requires multiple attempts to start, it usually indicates a decline in the battery's charge storage capacity. Second, check the battery's physical condition: a bulging casing, white/green crystals on the terminals, or leakage are all signs of internal structural abnormalities and require immediate attention. For maintenance-free batteries, a quick assessment can be made by observing the color of the inspection window: green means normal, yellow indicates reduced capacity, and black means the battery needs to be replaced as soon as possible. Voltage testing is a more precise method; when the static voltage is below 12V or the starting voltage remains below 9.5V, the battery can no longer meet the vehicle's needs. Additionally, if the electronic devices on the dashboard flicker or respond sluggishly at idle, or if the battery has been in use for more than 3 years (4-6 years for batteries dedicated to start-stop systems), it is recommended to replace it proactively even if no faults have occurred yet. It is worth noting that vehicles that have experienced multiple battery drains within two years need to have their circuits checked for leakage to avoid misjudging the battery's lifespan. Professional testing equipment can provide objective data through the State of Health (SOH) value; when the value is below 60%, the battery should be replaced. Avoiding long periods of parking or using high-power electrical appliances with the engine off in daily use can effectively extend the battery's lifespan to 4-5 years.
