Homemade Iron/Aluminium Furnace?

I am trying to make a homemade furnace that can melt iron and aluminium, to start out im am trying to melt aluminium foil. I have two furnaces and i can't decide which one is better and why. The first furnace is an Electric Arc furnace that runs of a dc battery charger that can spit out 75A at 12V, i use a graphite pencil lead for my electrode but that burns out to quick. I think this could be solved by using a larger carbon electrode like those in 6V zinc-carbon batteries. The second furnace is a propane blow torch furnace powered by a little hand blow torch, this gets the aluminium red hot but i think its being oxidized into aluminium oxide which raises it melting temperature. I ran it for about 3 minutes and it didn't melt anything. Im guessing if i added some fibregl insulation it would get hotter faster and if i let it run longer it might melt the foil. The other idea i have but haven't tried yet is to directly connect the aluminium foil to the battery charger and have a current limiting device in between so the chargers breaker doesn't blow. I would like to know which of these is the best and by best i mean easiest, fastest, hottest and cheapest.