Oops, you're right, I assumed a pair of Li-Ions.. What's your setup Superdave?
lol, just a driver from a Ebay Q5 dropin, 5-12V Vin range assuming around 3.5 Vout @ 800mA. I had it on a KD 5 mode driver with a protected 18650, it's about the same brightness in both setups.
I ran the same emitter up to 5V, 5.2A last night (wired 4P) and it was screaming bright and no angry blue. I bet i could direct drive it off of 2 123's and it would be fine.. lol
as for build cost.. i'm not sure how much the light meter was, the large piece of PVC was stuck in a wall, the smaller grey piece was from a vacuum system that we were building, all the plexi was just scraps and i used a hot-glue gun, roto-zip and a hole-saw to assemble it. Took maybe 45 minutes.
I might paint the outside flat black, right now i get 5-10 lux with nothing in it.
Thanks all!
I'll post up some more measurements of common lights tomorrow.