The 95+ CRI SST-20's seem to do about the same throw as XP-G2 S4's, little lower in lumens, nice upgrade in throw and CRI bump from 219C's
The 5000K SST-20 seems like a great compromise of excellent throw, lumens, and tint, if the lower CRI and tint is ok for you
Of course this depends on bins of the LED's used... Also what's missing is the amps these are pulling. You would assume the XP-G2's and XPL's would pull less amps.
So, finally did the tests with the 3500k SST-20 vs the LH351D 4000k.
Picture of die size comparison
Tint comparison with SST-20 3500k and LH351D 4000k on similar reflectors at 1 amp.
And by god is the 4000k LH351D green compared to the 3500k GA3 SST-20!
I also got a significant throw increase by swapping in the SST-20 in my Thorfire TK15, and a nice increase in red color rendition, probably given by the lower CCT and lower duv. It’s a pure 3500k tint at 1 amp.
I don't notice the green much in the LH351D's, but comparatively it could be lot more obvious. Also I got mine from Richard at MtnE - it's a P6 bin but that's all I know bout the tint.
So, after seeing the reports of the small springs being a bit too big sometimes, I have made some tweaks to the design:
Material: Beryllium Copper C17530 38% IACS Spring upper diameter: 4,5mm Spring base diameter: 6,0mm
Spring thickness: 0,8mm Spring height: 10,5mm
Total number of coils: 5
Plating: Silver electroplating
Same thing for the large spring:
Material: Beryllium Copper C17530 38% IACS Spring upper diameter: 6,50mm
Spring base diameter: 9mm
Spring thickness: 1,0mm Spring height: 12,5mm
Total number of coils: 5
Plating: Silver electroplating
Blue, i’m happy about the spring changes. I agree the first batch was sometimes too big and sometimes just right. Even with the new dimensions the “just right” cases would still be good and not too small.
I do wonder though, instead of changing the height have you considered just removing a coil and letting them be wider spaced? Once compressed with the same number of coils the height change will not be very noticeable. However, if you keep the same height, remove a coil, then after the first compression they will be shorter w/ less material so possibly even lower resistance?
Can’t really do this without making the spring quite a bit smaller, or affecting mechanical properties.
Did the math using 4 active coils instead of 5(the ones that affect conductivity in a flashlight spring), and it would make the spring deformation much higher. Instead of being 1mm of plastic deformation, it could easily go at 3mm, or even higher theoretically.
Even the manufacturer warned me about it, and recommended me to stay with 5 active coils.
You can do this easily with a steel spring of thinner wire, but not with a 1mm thick BeCu spring wire.
TLDR: Tried already, but the real world consequences would be too great to consider changing the design too much.
For my use in lots of different lights, I do have to be conscious of clearances, because many of the stock springs will compress flat into the thickness of one coil because of the conical shape where these don't because they are more cylindrical shaped. So the stock springs could probably handle longer cells. Of course if I used inner bypasses, I sabotaged the collapsing down of the spring anyway.
Also these springs are mostly stiffer than typical stock springs I see. But of course, a lot of my lights are true "budget", UltraFire and other no name brands. For ZY-T11 clones I'm working on, I'm cutting the small springs down to reduce the height of the compressed state of the spring. Should reduce resistance as well.
Not suggesting any changes, just have to bare in mind this stuff.
Even with 3mm plastic deformation it puts it from 13mm to 10mm, which is right where most medium/large sized springs are at. I’m no expert though. I think only the large spring could afford to lose this much height though. I’m biased since I (will) have both though.
Similar issues here. I find I can typically use 1 Blue spring on either end but then I have to bypass a stock spring on the other end to make up for the size/compression differences. I can rarely use both a large and small spring together as is.