Add this one to the official "Stupid Things To Do With A Battery Charger" list: never, ever, ever try to charge a 12v battery with a 18v charger because you think "it will charge faster that way." And in particular, when you are NOT charging the battery this way, remember to NOT reverse the leads!
The real lesson learned: never let the mechanical engineer on the team play with the electrical stuff!!! (right, Meech

) Otherwise, a bubbling, hissing, smoking battery will result, which has to be removed from the VCU Competition premises at a dead run by the head-geek while being grappled with a long-handled pair of pliers and welding gloves!!!
-dave