Re: What is the most efficient driver?
:welcome:
I dont know what driver to go for.
No disrespect, but if nothing in
this list grabs your fancy you're probably hard to please. :thumbsup:
One of the uses is for caveing where I do not want to carry any extra weight as I already tend to carry to much. I could easily want run times of 12 to 24 hrs. I sometimes take family and friends so have quite a few lights I do not want to spend $20US each on converting these.
The issues you raise:
1. Caving weight. Use AA NiMH cells, not those SLAs. But you knew that, right? :kiss:
I've thought many times of lugging an SLA spotlight into one particular cave just to have a look across a large chamber, but the thought of all that weight always puts me off. Three AA cells will sit comfortably on the back of your helmet - much handier than lugging an SLA around.
2. Runtime. How much light do you want for that runtime? My main caving light at the moment has three modes (four if you include a glow ring around the reflector) which have very approximate runtimes of 6 hours, 20 hours, and 60 hours (and, um, "glow all night") from three AA cells. I mostly use medium, or low in tight passages. (When I'm not caving it'll go for about 2 hours, 7 hours, and 20 hours on three AAA cells.)
3. Conversion cost. NZ$15.35 (US$11) for said light including donor body, plus NZ$5.64 (US$4) for whipping up the external AA adapter. Very versatile, efficient enough, and it's simply a very elegant solution to my lighting needs, both caving and camping.
BTW, the AMC7135 constant current regulator drivers which have the really great efficiency
IF the in and out voltages are about right can easily be used with 12V. Just use a couple of the LEDs in series with the board driving another LED. Make sure you use higher Vf LEDs to increase the efficiency. But with three suitable LEDs already you're heading toward US$20. Another reason to go with three AA cells.
IIRC the old Kennan board had an efficiency about 86% at 750 mA. (Above that and its efficiency drops markedly.) Even if you were able to find a board within budget with another 5-10% efficiency you would only have about 6-12% extra runtime. How much is that really worth?
That's probably enough food for thought for now.