Celebrating the independent kiwi spirit of invention.

Fabrication: 17-mode Triple Cree XP-G R5 Caving Headlamp

By Ian Mander October & November 2010.

Various notes not used elsewhere.


Triple XP-G Possible Modes
Mode Lumens Current Duration
Low 3 x 3.3 = 10
30 mA 2.75 days
Medium 3 x 25.8 = 77.4
general caving
180 mA 11 hours
option 1
3 x 48 = 144
demanding caving
330 mA 6 hours
option 2
3 x 60 = 180
demanding caving
410 mA 4.8 hours
Turbo 3 x 350 = 1050
large chambers
3 A 35 minutes

FWIW that turbo mode would be about as much light as a 45 W halogen bulb produces (ie, almost a car headlight). Heat sinking required!

There's not much efficiency gain at low currents, so there's not actually much difference in current required to produce 75 lumens between one and four XP-Gs (for example), but the total output of over a thousand lumens from three XP-Gs at 1 amp each would be "satisfying" and different optics could be used on the separate LEDs. I suspect 4xAA Eneloops would be required to provide enough voltage for the drivers to stay in regulation at high currents using AMC7135 linear regulators. (Yes, since confirmed.)

To drive an XP-G (or an array of them) at 180 mA (total) I'll need a new driver. The AMC7135 used in my present headlamp works very nicely with 3xAA cells, but the output of each one is fixed at 330 mA. So I want a constant current driver which can be set to 180 mA output and will run on 3xAA or 4xAA, or even 3xAAA.


Completed headlamp

This headlamp became a bit of a legend, if I say so myself. See the PDF write-up posted here: Tech, AHE Science Fair Aug 2011.pdf


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