I'm working on a project in which I want to control a few high-power LEDs via an Arduino, all running on a 12V DC system. A friend of mine suggested these LEDs as they are being used in the ridiculous flashlights given to some Google employees: http://www.digikey.com/product-search/en?WT.z_header=search_go&lang=en&site=us&keywords=SST-90-W45S-F11-GN400&x=-1451&y=-51
The specs claim that these should be run at 3.25V with a power draw up to 9A (but I'll probably want to run them somewhere below that). The question I have is how best to actually use these monsters. Using a straight up voltage-resistor-LED calculator comes out at using resistors in the range of ~1.5 Ohm 50Watt resistor so I ordered a couple of options in the 1.5-2 Ohm range, however this does not sound like a very efficient option as I suspect there will be a lot of heat generated on the resistor.
Does anyone have suggestions for alternative circuits to use to drive these? Checking ebay I found a few 120VAC options, but nothing for 12V DC. Optimally I'd like to be able to dim these, either by having a variable current source or via PWM.