Check the battery weak car battery. Fill the cells with distilled water. Auto Repair Tips Car Battery Car Fix Auto Repair The water component of the sulfuric acid electrolyte is used when the battery reaches 80 of full charge and gassing occurs. . That is never just water in the battery cells. Learn how to check car battery water levels with this guide from wikiHow. While a battery should only be filled after it is completely charged you should also check the water level before charging to make sure there is just enough water to cover any exposed plates. 7 For the type of battery you describe 3 years is not a horrible service life. Refill With Distilled Water Carefully. Look through the battery filler holes and check that the water level covers the top of the battery plates and separators. Again if you see dark light the battery needs water. A fully charged flooded lead acid battery will rest at 1270 - 127...