What would cause severe battery corrosion on 2007 Dodge Caliber?

Skippy722.....One word. Electrolysis. :) In the case of a battery it is the two dissimilar metals (lead,copper and even the steel bolts) are caused to corrode... either by their mere presence, or by some 3rd party chemical.In this case, it is battery acid and the act of charging a battery. That is why most corrosion is found on the Negative battery post. The constant overcharging of the battery increase the corrosion. If you find that you have more corrosion on the Positive post, I bet your battery is being overcharged. Then there is also the Hydrogen gas which is admitted by the sulfuric compound inside of your car battery, and very little of this gas is actually vented to the outside, but it does escape near the battery post. So, add the acid and lead reaction to this as well. That is why the older batteries had a felt washer between the battery post and the battery, to trap those gases. Clean you battery with a water and baking soda solution and apply some grease to the posts. This will not prevent corrosion, but it should slow it down. Here is some great information about the whole process. Hope this helps, good luck.