I’d like to hear anyone’s thoughts or experience on modding/building an XHP35/XHP50 single cell tube light.
EDC size using Convoy s2+, s3 host or similar.
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Many production lights on the market now in similar size: Tube Style lights with XHP35/XHP50
For myself I see no reason to use the XHP35 in a small flashlight. There are single 3.7 V LEDs with similar power or slightly less power but better tint on the market. The XHP35 needs four batteries or a 12 V boost driver like the H2-C (22 mm, may not fit into a Convoy S, but there will be a great new 17 mm boost driver from Schoki and Lexel soon.). The boosting losses kill any advantage of the lower losses at 12V between the driver and the LED.
The four dies of the XHP35 together are not smaller than that of single die LEDs so it will not make a thrower out of your light.
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The XHP50.2 has much more power than any single die LED but it needs two batteries or a 6 V boost driver like the H1-A (20 mm, fits into the Convoy S with some filing). The XHP50.2 peaks out at almost 5000 lm near 10 A so if your 18350 cells are not the best you can use a direct drive FET driver (like the Texas Avenger) to run it.
You will get a pocket rocket that runs crazy hot very fast and drains your batteries quickly. Without thermal control this light will self-destruct if you leave it on full power for too long.
Not a good feature for an EDC.
If you want the full power a triple or quad would give you a wider choice of LED types and tints. If you want a reliable EDC much less power may still be enough.
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Older mods with XHP50 and XHP70 suffer from holes in the beam spot. The new XHP50.2 and XHP70.2 are much better.
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In a nutshell: Both 35 and 50 (and 70) can be done, soon easier than ever. It just might not be what you really want. But who knows…
The XHP35 is especially redundant in this application due to the existence of the XP-L2. Any theoretical output advantages of the XHP35 are lost due to boost driver inefficiencies.
The XHP35 HI is useful in 26650 or multicell lights, where there is more space for a larger inductor, and you can use cells in a series configuration so you don’t have to boost as far.
Thanks, I didn’t know this! Can you reference or link any threads/posts where someone has done this?
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Thanks for your input and valuable info!
To clarify things, in the OP I only said “EDC size” 
…not necessarily for actual EDC use. :smiling_imp:
XHP35 HI is among the throwiest stock LEDs that exceed 1000 lm. Also, is we consider both throw and efficacy, it’s a Pareto frontier. The fact that it is not 3V is good - because it enables the use of boost drivers, adding to overall efficacy (6V would be better though).
When money is not scarce, I consider it the best LED for general purpose 1*18350-1*21700 lights.
Interesting. With that in mind I have to wonder then why so many manufactures are now producing smaller single cell 18650 lights with XHP35?: Tube Style lights with XHP35/XHP50
But maybe all of these were released before the onset of XP-L2? Don’t know.
Recently I was considering some XP-L2 emitters for an upgrade and asked Richard at MTN if he was planning on stocking them, (he said he wasn’t until the supply of regular XPL begins to diminish) but he added: “In my opinion, optically the XP-L is superior to the XP-L2, with less tint shift”
…Which for the time being steered me away from pursuing them.
Are XHP35 only available in 12v?
Yes, they are only 12V.
And AFAIK 12V boost driver is still significantly more efficient than a linear one….
Yeah, the tint of the XP-L is better (especially if you use an XP-L HI), and for most uses, the increased output of the XP-L2 isn’t worth the faster stepdown and worse tint shift. Likewise, the XHP35 also has to deal with increased heat generation, leading to faster stepdowns, compared to the XP-L.
The XP-L HI is still my favorite Cree emitter, and I think the XP-L HD (slightly more output) or HI (more throw) are still the most practical options for a straight body light. But the XHP35 HI is nice if you are looking for a thrower in 26650 or multi-18650 configurations. If you are looking for a hotrod, and don’t want to use a triple or quad setup, the XHP50.2 in the 6V configuration could have a niche use.
BTW. as to XP-L2:
At all but the lowest currents, XHP35 is more efficient.
That’s not the case with Samsung LH351D though.
Quite the opposite…. XHP35 is more efficient at modes other than low and always uses an efficient driver. This means that for any given output (other than low) it uses less power. And therefore generates less heat. And therefore overheats slower.
I’m curious as to how efficient the XHP35 drivers used in straight body lights really are. Reviews of the Klarus XT2CR, Armytek Prime C2 Pro, and other straight body lights using the XHP35 seem to show they fall short of their claimed lumen outputs, and struggle with fast thermal stepdowns. XHP35 lights with multiple cells in series seem to have fewer issues. My best guess is they are struggling to build a boost driver that can boost a single cell to 12V efficiently while fitting in such a small package.
And relative to the XP-L, some of the increased heat generation is simply going to be due to higher output - even if the XHP35 is more efficient, if it is putting out 1600 lumens compared to 1200 from an XP-L, you are going to get more heat.
I recently bought a Zebralight SC600w MkIV HI. It uses a XHP35 HI emitter. It seems very efficient, although Zebralight is known for efficiency.
So, you don’t have to mod a light. You can buy one stock.
As far as performance goes, it’s doesn’t have quite as much output as a XP-L HI light using a FET driver (and a high-drain battery). But, Zebralight runs the LED within spec, so it’s very efficient, and relatively constant-output.
Zebralight seems to be the exception. With the MkIII lineup, they were only aiming for ~1300 lumens out of the XHP35, while others were claiming 1600+ lumens. It looks like they are pushing their current lights a little harder. Would be interesting to see a review of the SC600 MkIV or SC64 by somebody with an integrating sphere to see how close they are getting to their target.
Yeah I’ve been looking at the SC600w MkIV Plus with XHP50.2 (2300lm) Very interesting flashlight, only 96mm long.
Exactly the same body as the one you bought, but much more output (and much more than an XP-L HI light using a FET driver and a high-drain battery). I’m thinking it may also have good efficiency / constant-output, being a ZL as you said.
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I’m aware that you can buy one: 
However, most are quite pricey, in the $100 range, there are a few that can be had for < $50 but no NW version for those ones.
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The purpose of this thread was more specifically about getting one of these emitters into a “Straight” Tube style light such as (S2+ S3 etc.) using a single cell, along with the possibility of building one with a NW emitter for around $50 or so. Plus I enjoy building things and the satisfaction that comes with it, even if it’s only assembling from off the shelf parts.
Yes, I considered that one when I was buying a couple of weeks ago. Looks very nice, although I decided it would be too floody for my intended purpose. I already have a few other Zebralights, and they’re generally pretty floody lights to begin with. The SC600 Plus model is even more floody than standard.
It is supposed to be their most efficient light, though.
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Ah, okay, yes that makes sense. You want an S2+ host, and a new driver and led combo. I’m not aware of any drivers that would fit, but I’m sure they must be out there.
Thanks TBone, this is exactly what I’m looking for, no time to try at the moment but hopefully I will be able to translate it with google.
Khas has also pointed me to a post where the H1-A was also stuffed into an S2+ (thanks Khas)
I also had the Desert Tan color S2+ in mind.
Or the S3 because I really like the SS bezel.
But it may be too hard (or impossible) to do with the S3 because of its integral LED shelf?
Also not sure if there’s actually any benefit for thermal management with the integral LED shelf vs the brass pill?
As Khas also pointed out to me, the Shoki / Lexel 17mm BLF 1S 6-12V Boost driver is in progress, so that should be perfect for this.
I think something like an MT-G2 or XHP50 would be very desirable in something like an S2+ so I don’t think it’s silly to try it.
I hope you do a mod thread if you ever go through with it because it is something I plan to get to eventually when I have more time.