Learning how to clean battery corrosion is pretty simple. Remove the negative battery cable from the battery and then remove the positive battery cable. Now mix up a 50:50 mix of baking soda and water. Pour this mixture over the top of the battery and use an old toothbrush or similar cleaning instrument and scrub any corrosion from the battery. Make sure you scrub the whole battery clean. Now rinse the baking soda - water mix off with clean water and dry the battery with a clean rag. You may want to use a metal brush to shine up the battery terminals. This will help make a better connection with the battery cables. Now replace the positive battery cable and then the negative battery cable. That's all there is to properly cleaning battery corrosion off of your car battery.