I have opened everything I can on the inside. It there is a space that I can not get to on the inside, there is a corresponding storage space, furnace, h/w heater, refrigerator, propane tank, generator, rear wheel wells
I have located said battery. It was indeed, Herman, located under the bed. I had to reexamine the space utilization there, and move the wood platform the bed sat on (It is two piece plywood hinged in the middle for access) that I thought was screwed down on the back side. This also explained the a hole in the back of the house (which went to the battery box to vent gases from the battery).
Thank you all for your help and suggestions.
Steve