Hello guys,
Please excuse me for joining this conversation, as I am a newbie in regard of the flashlight electronics topic, but I have a (general) problem, for which I think, a solution would be highly desired, as success in that regard could be perceived as a big improvement for many of us. (Also excuse me for introducing a problem, which does not match the concept of your latest conversation.)
I have read about the linear drivers across some pages and forum topics, which are used pretty much all across the baseline of Convoy products (S2+, C8), and many more similar flashlights.
Because mostly there is a significant difference between emitter Vf values (for given current), and battery voltages, they just convert the difference to heat, which leads to undesired efficiency loss, and worse heat attributes for given current levels.
I was lucky enough to make a few emitter swaps in my favourite headlamp model (Skilhunt H03), and I discovered, that heat is pretty much controlled with even the two highest output settings. I have read, that it has a driver, which converts the battery input voltage down to the Vf of the used LED (certainly, it has a buck driver), so it could stay fairly efficient, regardless the fact, that I used an emitter with considerably lower Vf across its current characteristics (change was from Cree XM-L2 to Nichia E21A).
But, that is not the case with any of the known linear drivers - so using lower Vf emitters with those drivers could mean even more heat compared to the older XM-L2 or XPL emitters, if they are used at the same current. (These emitters would be most new Cree whites, almost all Nichias, many of the monochromes /extremely low for mostly orange, red, and near infrared/ for signaling purposes) - Also, I would not like to direct drive these low Vf emitters.
Generally, I would like to ask for a solution, which could be used in a few smaller popular flashlight hosts, which can only support d = 17 mm driver plates (e.g. Convoy S2, Jaxman E2L), and probably they have limited space to fill vertically (e.g. it would be around <5mm for both of Convoy S2 and Jaxman E2L, if I remember it right).
So, for now, my question would be, that could you design a single li-ion battery buck driver for a d = 17 mm driver plate, or it has too many difficulties? (‘Moderate-to-high’ max. current, e.g. 2-3A for S2+, 4-6A for C8)
If at least one of you would like to, and would be able to put some effort into it, I am willing to donate for its development based on the needed parts list, and other factors/milestones. (I cannot offer more than a few $10, but I hope, others could join the funding of this project as well, if it can start.)
With a little exaggeration, my dream would come true, if I could use nearly any emitters efficiently and with controlled current levels with the above mentioned flashlight hosts (and it could be widely available across the flashlight users/lovers, then).