Sorry for the previous two posts; I clicked to quickly! On my 535, the battery is under the rear seat. It needs a vent hose to vent potentially explosive battery fumes outside the car. The tube on mine exits thru a hole in the floor. Perhaps you have a battery that could be used on a 535, and thus has the vent tube. I wouldn't think yours would need to be connected to anywhere, since it is adequatedly vented being in the engine compartment.