Today I installed two new batteries and I noticed something was not right, the volt meter did not go above 10-12 on my drive to work, normally would run around 14+, also noticed my air dog was louder than normal. Got to work looked under the hood and the passenger battery blew up, acid all over the engine bay. Went and got a new battery and seems to be having the same symptoms, I unhooked the pass. side bat. and it runs just fine, airdog is quiet and volt meter is at 14+. What would be causing this, the alternator is getting hot when both batteries are hooked up, and yes I have positve and neg correct. Did not find any shorts or anything, what would suddenly be causing this?