I’m new at this, and I’m trying to figure out what LED requires the least current to get about 400 lumens. High-CRI and a temperature around 3000k are important. A maximum output of at least 1000 lumens at 3A is also desirable. I can drive at either 3v or 6v (two lithium cells in series or parallel). I’ll be using the TaskLED dualFlex driver
The new XHP35 and XP-L look like strong candidates, and the XM-L2 is popular as well. I’m having a hard time making sense of the cree data sheets.
Well the XHP35 is a 12v, so that might be out. Getting high CRI in a high output bin will be difficult, which is why I would recommend an XHP-70 or XHP-50. The new XP-L2 might be a good option too, but not available yet.
Yep, 12v is out. Shame, the XHP-35 looked pretty good otherwise. Output over 800 is not as important as a very pretty beam.
I’ll look into several LEDs. Would that be several of the kind mentioned above, or lower output?
If I’m understanding the data, it seems as though the XP-L offers the lowest draw around 400 lumens, and is available with a high CRI and warm temperature. Does that sound reasonable?
I’ll be having at least two emitters. One dedicated to flood and one to spot. Can the XP-L perform well in both of those roles? Are there any recommended reflectors?
Have you looked into the fat MT-G2? Nice tint, floody beam…
You should be able to get a High CRI at 3000K in the G0 bin, around 500 lumens at 1.1A and 1000 lumens at 2.5A or so. This emitter can be pushed up over 12A, peaks around 9-11A. Kept in the lower amperage like you’re suggesting it’s a pretty sweet output.
High CRI XM-L2 is gonna fall way short, only making around 400 lumens at 2A.
XP-L in a T6 bin 90CRI would only be doing some 600 lumens at 3A.
Seems like the MT-G2 would meet requirements, delivering the requested 400 at 1A or so and 1000 at less than 3A, while doing high CRI and making a beautiful beam color and shape (in the right reflector) I have 11 MT-G2 lights, love em.
Contrary to popular belief, not all my lights are extreme. I have an Eagle Eye X6 with MT-G2 and PZL driver making 4.55A at the tail and housing a Ledil Iris TIR that is a very sweet combination. It’s running on a pair of Efest 18350’s. The PZL is, of course, an 7135 chip driver with dual channel and can easily be set up to do whatever current is required.
The only Watts’s I know live in Mississippi. My clamp meter measures in Volts and Amps. So that’s what I use to measure a light. Everyone that can punch buttons on a calculator can figure watts from voltage and amps, it’s an end figure, not the means. I like seeing the bits that make the results, so I use Volts in and Amps pulled. Efficiency? Could care less, I’m looking for light and I don’t care how hard the components have to work to make it happen.
This is how non-electronics flashaholics look at it, the simplified way.
Like this… I put 4 of the same cells, at the same charge (Volts) into a TN42 and when I point it at stuff a mile away the stuff has visible light on it. Bingo! That’s all I need to know.
If I can put 2 little Efest 18350’s into a copper battery tube and hit the switch for this…
But Dale, if you’re looking to get the least amps while producing 400 lumens like the OP asked, that makes it sound like battery life is important. And if you have the option of choosing 2P or 2S, then watts and efficiency (lumen/watt) are what you really care about.
In any case, I think currently a 6v emitter will give the best efficiency while retaining high CRI. My suggestion to the OP is the XHP, at least until we get some tests of the XP-L2. Although I’m not sure what type of beam profile the OP needs…
I just can’t wrap my mind around why watts matter. Given a voltage, we need amps to get to lumens. Watts are what happens once we get there. The specifics were 6V emitter, 400 lumens. The question was how low can the amps be to derive these lumens from a 6V emitter, so we only have amperage to work with to get the lumens. Only then can the watts be determined. So it’s the current that’s the deciding factor, watts really has nothing to do with it, it’s the “The End” at the back of the book.
When you go out of town on vacation to see family, you make sure you have the money to buy the gas to get there and back. Only after the vacation is over do you worry about figuring up the gas mileage. So it’s a statistic, it didn’t make the trip happen nor did it make it any more enjoyable, it’s just numbers crunching after all was said and done. Sure, you can figure before hand what your mileage Might be, so you can sort of guesstimate if you have enough money at current gas prices, but that won’t take into account the wind that turned and got in your face, or the long traffic jam you sat in and burned gas with the AC on. The final story always takes something different than the early numbers crunching, so again, you can’t figure how many lumens you’re going to get based on watts, you have to use amps, which is why all the spread sheets from Cree and Nichia and Oslon and Luminus state forward voltage and current.
Read the specifics again. It said 3v or 6v. If we are comparing an XHP to an XP-L, 1amp on one is not a direct comparison to 1amp on the other. That’s why watts matter for this particular question.
I read some more and played with some numbers and I think you’re right, the xhp 6v should be pretty good.
I’m making a caving headlamp. Battery life is important as I often spend over 12 consecutive hours underground and I don’t want to change batteries every two hours or carry that many spares.
As for beam profile, think of it as two lights. I’ll need a pure flood light that will be used a majority of the time and a spot light to supplement it when I need to see far. 400 lumens is the about the ideal output for moving around, but more is always better for lighting up a big room.
