Looking for assistance regardnig a Briggs and Stratton 422707 1214 01 lawn trractor engine. About three weeks ago I mowed the lawn and shut the tractor off. When I restarted the tractor about 15 minutes later the battery exploded (took the top right off of it). The battery was about 3 years old with no prior starting or running issues. After cleaning the tractor and replacing the battery, I placed a volt meter on it and recorded about 14 volts at the battery with the tractor running full speed. Being curious about what caused the battery to explode, I checked the voltage again last night and received a reading of 16 volts at the battery. I suspect the voltage regulator might be shot, however, could not locate one on the engine. The parts diagram lists a voltage regulator but I can't locate it.