Final arrangement to reduce tension on solder joints. Hope it lasts.
I like my olight st95utvn. This sample have xhp50.2. 4200 lumen and 300k lux. I run 10 minutes on high and this light can take heat very well. True search and rescue light.
very nice light you have, I guess it is de-domed to throw 300kcd.
I was thinking about bigger LED too, but I don’t like to throw away the stock driver. I was hoping CREE come out a XHP that is 3V, so that I can use the stock driver.
One thing I find is that the flashlight body is still warm after 10 minutes I switched it off from Hi mode.
It feels like it has a lot of heat to dissipate. I don't know is it normal, feels like heat is trapped inside.
But the flashlight body warm up fast.
I wonder what is the MCPCB temperature. I tested with 3.3V for like 5s, and it is already too hot to touch.
At 50cm you should be getting a “dark heart”. Otherwise the focus is probably off. The bigger the difference between reflector diameter and led diameter is, the bigger the distance where you will still have a “dark heart” in the spot.
At what distance did you measure the candela value?
I measured it at about 5.6m.
Do you think I should put the led further from reflector and measure candela at longer distance?
Thanks for sharing.
This reflector seems to be designed to have almost zero dark heart(donut) if the led is fit nicely inside. Right now my led is (maybe almost) fully inside the reflector and I can see the donut at maybe 5cm. But if I move the LED away from reflector by about maybe 0.5mm to 1mm, the donut will show easily.
I will experiment with it again with slight adjustment and measure candela at different distance.
Measuring at 5.6m is easily good enough (this has actually been tested for this light here with the stock SBT-70, which has almost the same diameter als the SST-40). You can check this by standing where the sensor of the lux meter is and looking straight at the light. The entire reflector needs to be reflecting the LED die, meaning that it needs to be yellow. The outer edges if the reflector are the most important.
Checking the focus should be done by shining the light outside at an evenly colored object which is at least 15-20m away. In this distance you want to make the hotspot as “sharp” as possible.
Did another round of adjustment and measurement at 12meter, didn’t notice huge improvement. Betore adjustment, candela measured higher at about 400kcd at 12m though. After i adjusted reflector to have donut in hotspot, candela is measured around 390kcd. I would say no obvious improvement after i adjust and measure for about 45 minutes. I still believe there is maybe 10% of improvement by adjusting reflector to nicest spot with the led. But donut might be visible at short distance.
After focussing the next step is increasing the current. The SST-40 can take much more than 5.3A. I would try around 8A.
Thanks for the info.
I measured at 12m distance and got 400kcd but it could be my lux meter to be at different sensitivity range.
A lot of factors and i could not get obvious improvement by adjusting distance between reflector and led alone.
Maybe i should fully dedome sst40 next time.
Yes, it is sucking 8A now. I didn’t measure current though, but i measure led forward voltage to be 3.66v.
The Vf can’t tell you much, there is a lot of variance from one LED to the next. It also depends on the temperature of the LED. The Vf changes with temperature. Deducing the current from this doesn’t really work.
What driver are you using?
Stock driver by Olight
I think the voltage should be good indicator of led current with good heatsink. Of course it’s still a indicator.
I just calculated what the maximum possible throw with this LED should be:
Area of reflector: 4185mm^2
reflectance: 85%
Transmission of lens: 96%
All three of the above where measured here.
Luminance of SST-40 N4 de-domed: 173cd/mm^2 @ 8.4A (see here, very close to maximum)
Maximum possible throw: 173cd/mm^2 * 4185mm^2 * 0.85 * 0.96 = 591kcd
Ya, i think i modded it, it was 4years ago. I can’t recall how i did it, but after searching excel files, i found some info that i calculate what resistor to put to lower the voltage from 4.5v to 3.8v for xml2. End up it is around 3.7v then. Now i use the same driver for sst40.
I can’t recall how i did that at all. I actually found my excel file in an old thumbdrive.
Very nice. I shall aim for this when i fully dedome sst40.
Since i didn’t dedome fully but should be close, let’s put 0.9*173cd/ mm^2.
Assume it is driven at 8A, let’s put 0.9*0.9*173cd/ mm^2
0.9*0.9*591=478kcd
Haha, i know nothing about the formula but it’s fun to have this calculation. Thanks for the formula.
I went with a de-domed XHP-50 in my SR90 but I also gutted/converted the battery pack so that I could use 6x 18650 batteries of my choosing, now they load in like a SRK does, only with 6 of them. I also changed the driver out for a Direct drive FET so I could max out the XHP-50. A de-domed SST-40 would most likely throw further and a de-domed XP-G2 might throw even further than that. I guess it all depends on which you prefer, more lumens or just trying to max the throw out. I really like this light with the de-domed XHP-50 in it, throw is incredible and the amount of lumens that it throws is ever more impressive. I have lights that on paper throw further, but in real time use the de-domed XHP-50 in this light is far more impressive.
Ya, these are very attractive light by Olight. I am not impressed with their X7 or X7R nowadays. I use highest mode for 5-10 minutes. I prefer big one for that purpose.
My battery pack is under a lot of stress with this SST40. With 3 dots battery remaining, when I switched on Hi mode, it will become zero/one dot battery remaining. One day I will need to gut it too.