Thank you, I’ll do some research into that suggestion.
Yes Zebralight is great and would do a good job, however part of the reason why I want to make my own design is because I want to create a smaller design for the forehead and also have the versatility of my own battery pack options e.g single 18650 on the back of headstrap (better weight distribution to Zebra), 2+ parallel in backpack/waist strap or even 21700’s etc. Not to mention I love projects like this and being able to show off my own design
Same as per my previous comment. Plus a 21700 like the Acebeam H30 is too front heavy and would be a PITA running for hours having to constantly readjust it.
Not sure about which is more efficient but i don’t think there’s any significant difference at the output you’re planning, especially when taking tolerances into account.
Another option for a cool white tint is the 3v version of the XHP50.2 which you can then use with the LD-x4 driver.
XHP 70.2 with a boost driver is hard to beat but optics choices are limited.
Buck driven triple or quad LH351D would be extremely efficient as well. And yes, buck is needed. Even with relatively high voltage emitters like LH351D we’re talking about linear driver eating a quarter of power at lower modes.
ADDED: Buck driven XHP50.2 would also work well.
The OP didn’t ask about 1 lm but 200-1000 lm range.
XHP50.2 should be just under 2.9V at 1100 LED lm or 1000 OTF lm. Considering circuit losses that’s marginally too high but close enough that maybe it would work for the OP if they are just a little short of the target. But are LiFePo4 better?
@bmengineer - Right I’m following you now, I would much rather the constant current output regulation for consistent brightness.
You’re probably right and the differences may not be worth fussing about, but it’s still something I think I’d like to test. If I was to go with 3V LEDs, I’d probably stick with the more efficient XP-L2’s plus there seems to be more CCT & Bin options.
Since making the post I have realised exactly this optic limitation for the XHP70.2. I think I’d have to stick with XHP50.2 or equivalent size - the 20mm x 10mm optics are probably the largest I’d want to use.
I don’t think Buck Driver is an option because I only want single lithium cell input (or parallel) so ~3-4V.