Your vehicle will charge the battery no matter what position the disconnect is in...the umbilical actually has a direct connection to the battery just for that reason. That is one of the reasons that you should unplug the umbilical when you are using power from the pedestal; most newer vehicles have a relay that disconnects that charging circuit when the vehicle is turned off to prevent any feedback to your tow vehicle's charging system, but, just in case, unplug the umbilical anytime that your RV is hooked to 120v power.
Your Carbon Monoxide/LPG detector is also hardwired to the battery - it will work regardless of what position the disconnect is in; a safety design so that no matter what the power condition is, you'll be alerted to a possible LPG leak regardless. Your breakaway switch is wired that way also. Again, a safety design...if you have a battery, and it is hooked up properly, the breakaway switch should have power, and you should never tow without a battery being hooked up for just that reason; no battery = no emergency breakaway braking on the RV in an emergency.
Those two items, along with, probably, your stereo (it has a digital clock that needs power all the time so that you don't have to reset the clock whenever you use the battery disconnect) are the two "biggest" parasitic draws on your battery and why, even when the disconnect is pulled (pushed actually on most FunFinders) your battery will usually go dead in a few weeks without charging.
My 2 cents, your mileage may vary...
2 Cats; J-Lo and Ragamuffin :R
2014 Thor Tuscany 40RX DP
2011 Ram 2500 Longhorn CTD HO
2011 Keystone Cougar 318SAB (now gone)
2008 FunFinder X 210WBS (Sadly gone)