B+ motorhomes

Burl- cheeze1 is right on, just need to wait a bit to do the work. Chemicals react pretty slowly in low temps, including acids. I would buy a spray can of acid neutralizer from an auto parts store or Wally-World. Spray the whole area it will come out yellow and turn pink in the presence of sulphuric acid. I have done the same thing on an earlier rig and overfilled the battery by mistake. Then the converter charges the unit till the bubbles force out some of the acid. May be a good idea to buy a specific gravity checker and remove some of the electrolite. After spraying the neutralizer, let it sit per the instructions, rinse with copious amounts of water in an area where you are not worried about the affects of the run-off. Let the whole thing dry, repeat the process more than once if necessary untill the neutralizer does not change color. Baking soda will neutralize the acid, but spray on neutralizer will give a positive reading if it is all gone. Don't forget the cables and any straps or tie-downs will probably have to be replaced. When your sure it is all clean and dry, wire brush any remaining corrosion and spraypaint the area before re-installing the battery. I think Sears has acid resistant battery box paint available, at least I saw it a few years back. Good luck.