Appropriate Converter Board Question

I have been referred to your forum for help on a project I am working on. I am trying to drive a Luxeon III LED at 3.9 volts and 1000 mAh with 3 X AA NiMH rechargeable batteries @ 4.2 Volts total. I believe I am looking for the BadBoy M1000 step-up converter, but am unsure if this is the correct board. Does this board exist, and where can I purchase it? Could someone with experience with this please explain the draw-backs and issues that might make this choice more or less plausible? Does anyone have a more effective idea. TIA for any help.

for 4.2V battery source, you may get away with a simple resistored DD design.

I wanted to utilize a converter board instead of direct drive to even out the current (BB=current regulated) and give a more even light out-put over the life of the batteries. I can use different NiMH batteries to give me a total of 3.6 V. Would that work? And do they make a BB1000 mAh version?

Go to The Sandwich Shoppe for all your BadBoy info. Also there you will find Mad Max, Down Boy, and Wizard converter boards. The Badboys are regulated boost. Madmax's are boost, most are wide open unregulated. Down boy's lower voltages to match the leds when using higher input voltages. The Wizards are supposed to do both buck and boost, depending on what is needed and condition of batteries. I beleive the Wizards are still a bit of a work in progress. Check with Sandwich Shoppe for details and accurate info on these boards.
I have a BB500 from the Shoppe. In a Mini Mag host It Rocks.

cheers,
zwf

The problem with using the BB is that the battery supply voltage is greater than the Vf of the LED you intend to use. The BB will supply it's rated current at the LED's Vf. Input voltage higher than the LED's Vf will destroy the BadBoy.

The Vf and your input voltage are so close, it's kinda tough to suggest buck or boost.

If the voltage sag is enough, you might be able to get away with the BB. I think I remember Wayne saying that a couple tenths of a volt higher input voltage would be okay.

'drive a Luxeon III LED at 3.9 volts and 1000 mAh with 3 X AA NiMH rechargeable batteries @ 4.2 Volts total'- if it really is 4.2v, it isn't NiMH (see below).

This is a good direct drive application unless you want to guarantee exactly 1000ma. 3 x AA NiMH will operate at around 3.7v with a 1 amp load (they are only 4.2v hot off the charger, and will quickly drop to 3.6-3.7v, which should be just right for a K bin Lux III. I have one running on 3 NiMH Cs @ 1.2 amps and another running at 1000ma from 3 Ds. Both of my FT-3Cs run at about 840ma from 3Cs. The NiMHs have such a flat discharge that I don't personally feel a need for regulation. Note that AAs have about the same internal resistance as Cs so should give you about the same current (for 1000ma anyway).

If it is some other bin or you want better regulation, the BB or some of the other circuits posted here will work. One question is how much room do you have for it? There was a recent post about this, but I don't recall what it was called - someone will mention it soon, i'm sure..........