Food and Entertaining How do I check the water level in my battery? How do I check the water level in my battery? https://www.youtube.com/watch?v=3PLSztkJGqE What is the role of battery water indicator? Instantly know if your battery needs water! No more struggling to peer into the vent hole to know if your battery needs water or not! ... Just remove the original battery cap and replace it with our level indicator.