What will be powered by the converter without any battery just depends upon how your RV is wired. If the battery has only 1 connection then most likely it will supply everything. If there are multiple wires to connect to the positive side of the battery you should probably connect them all together, must as they would be if connected to a battery, but with a bolt or such. When you do that, make sure that you insulate that connection so that it won't short out, and even if there is just one cable to each side f the battery, you still need to make sure that the positive cable is insulated and will not short out to anything. My 40 years doing electrical repair work has taught me to put great value in insulating connections.