So, you're saying that the Red Lux III is pulling out more current from the same battery pack (4.5V)because it requires less forward voltage (2.9V) than the Blue Lux III (3.8V)? I think I understand that concept.
If this is correct, then the voltage requirement of the LED combined with the battery voltage is really the only determining factor for the current output on the MR board. If this is correct (and its hard for my brain to understand this stuff easily without alot of repitition and clarification- sorry), then why do people have the impression that MR boards only put out around 900 mA? It seems that the MR boards are not really limiting current at all because when you increase the voltage (like adding another AA) or use a LED that requires less forward voltage, then the current goes higher.
I've heard the same thing, that is why I posted this thread - because I was noticing a difference
Am I correct in my understanding that a board like Crystal Focus (or even a buckpuck) will put out the set current regardless of the LED (regulate current)? Doesn't matter if it's a Blue Lux V or a Red Lux III or if the battery pack is 7.2V or 11V, if the board is set for 700mA, then the LED will "see" 700mA?
Essentially, yes. The CF does vary a little bit. For example, if you power a 3.8v LED with a 7.2v pack (which puts out 8.4v at full charge), it will probably read at 1250ma when you set it to give out 1500ma because it intelligently monitors how to best drive the LED given the operating parameters.
Erv' wrote this to me:
Instant consuption of current depends on the batt voltage versus the forward voltage of the board. The closer you get to the luxeon forward voltage, the more in "direct drive" you are. When you reach the forward voltage (like 3.7V for a green, for instance), you'll read 1.5A on the multimeter. But at 8V, you read less, while the brightness remains the same.
Maybe people just assumed that MR boards put out around 900mA max because they only tested their board with a Blue or Green Lux III with the standard 4.5V battery pack (which is about what your tests got).
I though this might be true as well
I don't think Xsaber tested any K2s. The most interesting of his tests was the red III at 1500mA. That's perfect for a red III. Maybe I need to get a red III for my Vader board...
I actually did test a green K2 and got the same performance as a lux 3. So at least the board I have are perfect for driving K2s, although I've always been unimpressed by K2's performance...
Also, rebels have a lower forward voltage and that is why you are getting a higher current performance out of them...
One question for Jedi-Diah - did you strip the negative wires (the rainbow of colors) coming out of the MR board nice and long? I've found that sometimes one or more leads can be missed and thus lower the voltage.