Furnace/Battery Help and Black Water tank

Colder weather coming on! Tested my heater, works well. My question here is how much battery power, if any, does it use to run it or does the propane do it all. I am going out camping without hookups. How best to have some warmth without draining the battery.  I don't quite understand if the thermostat is powered by the battery when no hookups. For that matter, does the water pump have the assist of the battery?And the black water tank. This year the read out inside always reads "3 lights", whereas the grey water goes down to "1 light. when I have dumped. . The grey water  starts (when I start to dump) with 3 lights , goes down as it should. I read that something may be hung up on the level gage and only way is to keep an eye on it, if it is constant in this reading. OR take it to your dealer.  Dealer is some way from me, that would not be bad, but they may have it for months before I get it back..   Comments if anyone has the problem and any suggestions.

Unfortunately the furnace uses a ton of propane and is also a battery hog.  I wouldn't worry too much, the pod is well insulated and even down in the 40's our furnace rarely runs overnight with 4 of us inside.  The water pump is battery powered, but the electric element in the water heater is 120 volts only so when you are boondocking you must use propane.

The black tank in any RV is a problem.  My black and gray tanks have the same behavior as yours.  I've read one solution is to add some water softener after each tank flush - it makes the water slippery so everything theoretically slides out off of the sensors.  I haven't tried this yet.

Oh, one way in which I save both power and propane is to only turn on what I need to use when I need to use it.  In other words, I keep the rocker switch in the off position for the propane water heater until I really need it (i.e. to wash dishes or take a shower).  I also turn any lights off that I don't need and turn the water pump off as well during the day when I'm outside hiking or playing.  The water pump switch really doesn't matter whether it's on or off if you don't have any leaks in the system which could make it cycle on and off constantly, but it does give me some peace of mind.  I also turn the furnace off or really low during the day to save on propane.  

You attach the wand to a water hose (not your drinking water hose), turn off the water pump so that when you open the toilet flush and shove the wand down in the tank, you're water pump won't constantly cycle just to refill the bowl.  What I do is move the wand up and down and twist it side to side so that I get the whole tank sprayed down.   

I've found that soap scum also inhibits the sensors as well, so what I do is pour the softener in both the gray and black water tanks.  I also add a little bit of that deodorizer/treatment stuff that is specifically for RV waste water tanks into both the black and grey water tanks after each flush.  The softener won't hurt the tank at all.