Sst light mod ?
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DIWdiver
Flashlight Enthusiast
It depends. Looking at my old Luminus data sheet, it shows a range of 500-1200 lm at 3.15A, depending on which LED you have. So to get 900 lm, you could have a driver set as low as 2.3A or as high as 5.4A. But depending on who built the light, you might not even want to depend on that range.
An XM-L2 is generally though of as a 3A led, but if you have a poor heatsink, you can burn it out below 3A, and if you have a really good heatsink... Let's just say people have driven XM-L's over 5A. I don't know, but Gen2's should be as good or better.
My gut says that if you have a decent current-regulating driver, you should be fine. The Cree will give you more light and less heat, as well as longer battery life.
On the other hand, the Vf is much lower on the Cree, so if you have a really cheesy driver (or none at all!) you could end up seriously overdriving it.
I don't know if that helps much. Maybe if we knew more about the device it's in, we could help more.
An XM-L2 is generally though of as a 3A led, but if you have a poor heatsink, you can burn it out below 3A, and if you have a really good heatsink... Let's just say people have driven XM-L's over 5A. I don't know, but Gen2's should be as good or better.
My gut says that if you have a decent current-regulating driver, you should be fine. The Cree will give you more light and less heat, as well as longer battery life.
On the other hand, the Vf is much lower on the Cree, so if you have a really cheesy driver (or none at all!) you could end up seriously overdriving it.
I don't know if that helps much. Maybe if we knew more about the device it's in, we could help more.
Thanks man , sorta backs up my thinking, but im not really sure how drivers work . The overall power should be ok but will the voltage which I think is higher for sst kill the xml2 ? Thats what I am worried about. Basically im looking at turning an old light into a thrower, hopefully with just a simple emitter swap. The sst was only chucking out 900 lumens max, which isnt alot for it which is why I thought the xml2 might be ok.
Thanks
Thanks
DIWdiver
Flashlight Enthusiast
What's the light? If we can identify what the driver is doing, we can be pretty sure whether it will be okay for the XML.
A good driver keeps the current constant and allows the voltage to change. This is because you want to put a specific amount of current through the LED to get the light you want, and you don't know exactly what the voltage will be. In fact, even once you build the light the voltage isn't constant. As the LED heats up, the voltage is reduced, but the current stays the same. A good driver will handle all this for you without you even knowing what's going on.
A good driver keeps the current constant and allows the voltage to change. This is because you want to put a specific amount of current through the LED to get the light you want, and you don't know exactly what the voltage will be. In fact, even once you build the light the voltage isn't constant. As the LED heats up, the voltage is reduced, but the current stays the same. A good driver will handle all this for you without you even knowing what's going on.
http://www.candlepowerforums.com/vb...rom-S12-including-outdoor-beamshot-comparison
One of these. I would have thought the driver is on the better side of things but who knows !
One of these. I would have thought the driver is on the better side of things but who knows !
DIWdiver
Flashlight Enthusiast
Based on that review, I would say that light is capable of substantially overdriving an XML. Note 18W input at 4.0V. With lower Vf, an XML2 would probably be driven at 4.5-6A until the battery is even further discharged, meaning it will be overdriven for some time after the battery is charged.
I would agree the driver is probably pretty good, just not well suited to an XM-L2. A low-Vf LED that could handle the higher currents that driver puts out would really be a great performer in that light.
Perhaps you could ask 4sevens if there is a fairly easy mod to reduce the max output current. Changing the max current and the LED would be a pretty sweet mod to that light. You'd get longer time before thermal protection kicks in, much longer battery life, and possibly even higher output as well. But it might be a real challenge fitting an XM-L where an SST-90 was intended to go.
I would agree the driver is probably pretty good, just not well suited to an XM-L2. A low-Vf LED that could handle the higher currents that driver puts out would really be a great performer in that light.
Perhaps you could ask 4sevens if there is a fairly easy mod to reduce the max output current. Changing the max current and the LED would be a pretty sweet mod to that light. You'd get longer time before thermal protection kicks in, much longer battery life, and possibly even higher output as well. But it might be a real challenge fitting an XM-L where an SST-90 was intended to go.
