How often you supposed to fill battery water in the car battery?

Modern cars typically do not require manual refilling of battery water. Most modern vehicles use sealed lead-acid (SLA) batteries, which are maintenance-free and do not require adding water. However, some older vehicles still use conventional flooded lead-acid batteries that require periodic water refilling. The frequency of refilling will depend on the car model, driving conditions, and weather. In general, you should check the water level in the battery every few months or as recommended by the vehicle manufacturer.