Hello, all. I was thinking about another build and I would like to build a high efficiency light to maximize runtime. I would primarily use this light for camping or hiking so runtime would be prioritized over output. I think I would be shooting for 250 lumens on max output. It is my understanding that certain emitters and drivers are more efficient than others and I am asking for recommendations. In true BLF style, I'd like to keep the cost down as much as possible and utilize a convoy S2+ host I have sitting around. I was thinking a low vf led with a buck driver would be possibly the best option? Thanks for the responses.
I am not sure if this will fit your requirements, but here’s my suggestion.
I’ve been using some drivers with Bistro HD OTSM, made by Lexel.
Here you can see the options you have to configure your modes: [UPDATE:v1.7.1,Q8&1chanOTSM]bistro-HD, bistro your way. OTSM, eswitch(devel), Vcc reads, safe_presses, turbo timeout...
I currently have 4 flashlights (including a Convoy S2+) configured on mode:
I have Moonlight enabled, and then this 150 lumens mode, and the possibility to access turbo and blinky modes through a longer press.
It is super useful for indoor and outdoor and you can have plenty light to navigate different spaces without blinding you or another person, and without having a lot of modes on the way you want.
Yep you want low Vf and also larger light emitting surface so using multiple LEDs in parallel or a 3V XHP50.2. There are some 17mm buck drivers on kaidomain like the BD39 and CF FX-17A. Mode levels are a bit limited on those.
Thanks for the ideas! It looks like the xhp50.2 would make (roughly) 250 lumens running at 375 milliamps (~1 watt) and have a forward voltage of 2.65 volts. This would be about 8 hours of runtime from a fresh 3000 mah battery. For a single emitter light, that seems pretty good. I’m wondering however if it would be limited by the battery voltage as the cell was depleted. How much higher does the cell voltage need to be above the led forward voltage with a small buck driver? Would a multi-emitter light fare better?
At that low current I think the driver wouldn’t need very much voltage overhead. I’m not sure how much but I bet it would be regulated for most all the battery discharge.
The 3V xhp50.2 is essentially 4 XPG3 dies in parallel so it has a very low Vf even compared with most multi emitter combinations.