I have been told by a reliable source that exchange bottles, although seemingly cheaper have issues:BCF fill them cheap enough and Bunnings does a 9kg exchange for around $21 or so .
I wouldn't bother doing it myself
As Middo said, you need a decanting 45kg bottle. It is just not worth the grief and the potential safety implication with sparks and sources of ignition close by. If you shop around, some places are pretty cheap and as stated above, its not worth the grief. I am a gasfitter and I get them filled at the shop. Sure it costs, but I would rather be safe than sorry. Blacky, I wont go into how to do it, as many people read these forums, just don't! Sometimes people have spare 45kg bottles half filled with gas, but they could be butane and not propane of a mix, but that's another safety issue. A proper re filler will sell you the correct amount and type of gas (propane).
Be very careful, car gas Lpg Is NOT the same gas mixture as the gas for vans and BBQs. Using car gas in the van can be very dangerous!Well, this all came up after a bloke i know offered to fill my bottles up at his place as he says hes got the adaptors necessary. Anyway, after talking to another mate today, he told me how he does his.... He has an lpg tank from a car he wrote off in a frame which he straps down to his ute. He takes it to the servo and fills it up.. And then uses an adaptor to fill his 9kg bottles from the big tank. Gets 4x refills from the big tank.
And to save a few bucks,Haha well there ya go.. Just shows how different people get things done huh.. I wont be filling mine myself, i use my local independent camping shop (also does my home brew supplies there) but jeez these blokes reckon theyve been doing it these ways for years. Never had a drama apparently. Farmers have a way of finding ways to get by with what theyve got on hand.