Even maintenance-free car batteries can acquire corrosive buildup, which is produced when hydrogen gas produced by the battery comes into contact with dirt and sediment on the surface of the battery. Removi. Open the hood of the car and use the support bar to prop it open.Locate the battery within. Sprinkle the terminals with baking soda.Scrub the terminals and the posts using a special battery terminal brush, inexpensive and available at most auto parts store.This special brus. Place the positive terminal back onto the positive post.Hand-tighten the nut until you can no longer turn it.Place a socket w.