現在的車用12.6v電池一般是不需要加水的。有全封閉的，也有帶密封很好的蓋子的。後者可以看水位或加水。

Once upon a time all batteries required water to be added. In fact, checking the water level was a standard procedure during an oil change service. Today, most batteries are maintenance free. Some batteries are sealed and some have removable caps. During the life of the battery, most people will never add water. If your batteries have removable caps, there’s certainly no harm in removing them and adding water (distilled only) if the fluid level is low. If you are adding water periodically, suspect that the charging system is overcharging the battery and “boiling” off the water, which needs to be fixed.