Here is the data from the datasheets presented by emitter, and by temperature, i didn’t extrapolate beyond 3A, but someone else can feel
free to do so
I wonder what real world values will be like. I use the panasonic 3400s which don’t hold their voltages too well. I was planning on building an XML-2 drop in with sinkpad + linear driver which would only make this high Vf issue worse.
Do you guys think it would just be better to use the standard XML or maybe just not use a sinkpad?
I just added a feature to my LED analyzer device (Any interest in a LED/Battery analyzer device?) that lets it sweep the LED with a range of voltages and records the various LED parameters. He it is sweeping an XML from 0 to 1.8 amps. At an LED Vf of 3.000V the LED was drawing 1.225A and 3.675 watts. Don’t have any XML2’s to play with.
I’m considering using a sinkpad and XM-L2 in a host too small to dissipate all the heat, so being a bit warmer will lower the Vf, i haven’t done the math, but i am hoping for more output vs the stock XM-L on aluminum pcb
Looking at the first two graphs GB posted in #6, if you take into account the different scales at the bottom they seem almost identical. Both start and end at about the same place. To be usefull as a visual comparison, the scales need to be the same.
If you keep the XM-L2 around 2.5A you should be good to go. I look at it this way, you can get a nice neutral tint XM-L2 with about the same brightness as a XM-L U3 but the U3 will have a cool white tint.
I only use high mode for short 3 or 4 second bursts anyways, low and medium mode is what I use the most.
Exactly, me too - considering it for a Convoy M1 - got it running at 3.85A but with the stock U2 emitter and getting only 10% better over the 2.8A stock setup. Interesting because it gets hot quick and on the light meter in the lightbox, it dropped quick, real fast for the first 2 secs - seems like no where to go with the heat. Im suspecting maybe a bad LED reflow or bad star maybe because I got a good thermal grease under it, and sanded/polished the contact surfaces, but no room to add any copper in the pill - really like the quality of this small host though. Think a SinkPAD could be a big benefit for this type of small host design - will be doing it and checking the result.
funny, thats the light i am currently using
Anyone know if the LG 4.35v batteries up on FastTech today would help the Vf issue with XM-L2 single cell lights? I suppose it helps if you could charge them to 4.35v - I don't have a charger than can do that.
Another interesting battery today up on FT is: Sony US18650VTC3 18650 1600mAh 3.7V , rated at 30A discharge. If it's lower resistance than the 20A rated Samsung 20R's, it should do better on the XM-L2/SinkPAD high amp single cell lights.