granolaboy wrote:Could one skip the step-down module if one already has a dc-dc converter putting out 12v?
Yes, they initially are designed for 12v vehicle application, there is limiting resistor inside the light casing.
As in, you looked in and found one? If it's just a dumb ballast resistor, that's awfully disappointing. The description states "with High precision constant current drive, make
sure that the brightness is same under any input voltage." That sounds like to me an actual buck LED driver instead of a simple voltage step-down. Are you willing to open up all the guts and post pictures?
Also, I can't find specs for the actual emitters. Going on "USA BrigeLux 45mil chip" leads me to this data sheet
, but that product is much "bluer" than I'd expect this light to look. (Dominant wavelengths all right around 450nm is really blue, not white with a blueish tint.) Wish I knew more. From the measurements you listed it's almost certain that the LEDs are wired in series and are getting 1amp.
It would be really nice to be able to put a knob on it to dim the light as needed. Many drivers have an adjustable current limit with a 0-5v pin or leads for a 0-5k pot. Barring that, if it's a constant current LED driver, it's got to be using some resistor to sense current. Tap a pot onto that and you're golden. Worst case, this is a steal for a lamphead with emitters, optics, and proper heatsinking. I'd buy a couple and attach my own drivers at that price.