A few days ago, I was looking for help diagnosing the reason my Aux battery
was going down in a few days.  Well, I never actually 'diagnosed ' the
reason by testing with my multi-meter, but I did fix the problem in my own
dummy-way.
  By trial and error, I isolated the current drain to the Sony stereo.  It's
bugged me anyhow, since I installed it a few months back, that the head unit
always stays lit up quite brightly (since I have it wire into the Aux.
battery without any connection to the ignition or the vehicle battery for
camping reasons..)  Others responded to my query saying they, too, had
encountered battery power drain from this type of install.

  So I stuck a toggle switch into the power supply wires, put it next to the
steering column under the dash, and no more low coach battery..No bright
light from the dash when we are trying to sleep, either...

  Thanks, everyone who offered advice.
  Don Hanson