Originally Posted by Sweetbriar
From the permanently mount RV tank? No. Both the big tank and your portable bottles are filled with liquid propane that boils off as a gas that you burn. No way to get liquid out of the RV tank, easily, to refill the portable cans. I've heard of using a 20 lbs barbecue tank flipped upside down to refill portables but haven't had a need to attempt.
I have done this.
With the appropriate adapter in place connecting the small tank to the 20 lb tank, first you put the one being filled and to be put in the freezer for a half hour to an hour.
Then the 20 lb tank needs to be more than half full.
Yes, turn it upside down before opening the valve, and fill in this position.
Beware, the shrader valve in those little green bottles will eventually go bad.
Then they leak!
Happened to me too many times, now I have an adapter for the 20 lb tank to run my grill, or stove top, that those small bottles connect to.
As for on the rig:
I believe it is better to have the connection, inline on the rig, between rig's tank and regulator, then use a 20 lb tank hooked up with the rig's tank shut off tight.
Save the re-filling to the professionals.