Keeping your RV batteries alive takes a few steps to ensure they last as long as possible. Make sure you never let the water go below the lead plates. Keep the water topped up to about 1/2 an inch above the lead plates. You can see them if you lift the battery cap and look down inside. Used distilled water. How often you need to check them depends on your usage, but generally speaking it is a good idea to look every month. Make sure your RV batteries are getting enough charge