Question: Why do some batteries need to be filled with water, and some batteries do not need to be filled with water?

Label: Q: Why do some batteries need to be filled with water, and some batteries do not need to be filled with water? Answer: The battery with water is older. Generally, the water in the battery must be added to the water before the battery can be used. However, this kind of battery is slowly withdrawn from the market. The country has already stated that it will be washed out because of pollution. The battery is maintenance-free and does not need to be added with water. There is no need to add water or electrolyte during the life cycle, only normal batteries are needed.