I’ve got two zoomable 1x18650 ebay flashlights which are the same. When zoomed to the max, the pattern of the emitter looks like a XP-G2, according to Cree, Luminus, Seoul … LED comparison. The XP-G2 is rated for 1.5A whereas the XML-U3 is rated for 3A. What’s really odd now is that both flashlights appear to have the same brightness, but the one with the XML-U3 get’s noticeably warm. This brings me to the conclusion that the led is probably driven at 2-3A. But as the XP-G2 is rated for 1.5A it should be the one which gets really hot, but it doesn’t.
Without knowing more about the actual lights and taking some readings you simply won’t know.
CREE’s rated specs are not always what can be used. For example, many here have run XP-G2’s at 3-5amps and XM-L2’s at 6amps+
That said, most stock off the shelf lights are not driven hard. If you have a DMM you can take a tailcap amp reading and see what they are pulling from the batteries easily, this will give you an idea how hard they are being driven.
In terms of heat, well this is likely to come down to the thermal path and heat sinking from the different torches, just because they look the same/similar on the outside, doesn’t mean they are constructed the same.
As for brightness, the XP-G2 has a smaller die and higher surface brightness than an XM-L emitter, although is physically smaller. It puts out less lumens, but due to the higher surface brightness means it works well with a zoomy light.
To complete CD's story, the XP-G2 has a higher spot brightness compared to the XM-L and that is easily interpreted as more light coming out. It is actually easy to solve that with zoomies: did you asses the brightness difference when zoomed out?
@ CD, both lights are part for part the same, I completely disassembled them.
Unfortunatelly I don’t have a meter to measure the brightness yet. I visually compared both of them in max/min zoom levels at a wall. But since they have different color temperatures it’s quite hard.
I think I have to do some more testing, measure the amps (but first I need a new fuse), make some beamshots.
Everything is exactly the same aah, shit, I forgot to mention that I modded one of the lights so it now uses the XM-L2. My humble appologies for the confusion :(. To ensure that the previous discussion still makes sense I decided to explain it again in this post:
I’ve got two zoomable 1×18650 ebay flashlights which are exactly the same. When zoomed to the max, the pattern of the emitter looks like a XP-G2, according to Cree, Luminus, Seoul … LED comparison. The XP-G2 is rated for 1.5A and a XML-U3 is rated for 3A. In on of the lights I replaced the emitter with a XML-U3 from fasttech. What’s really odd now is that both flashlights appear to have the same brightness, but the modded one with the XML-U3 get’s noticeably warm. This brings me to the conclusion that the led is probably driven at 2-3A. But as the XP-G2 is rated for 1.5A it should be the one which gets really hot, but it doesn’t. Also my modded one with XML-U3 should be brighter I guess
emitter amperage readings, tail cap amperage readings, Vf of each emitter, actual OTF lumens readings, Lux numbers, winning lottery numbers…
And specifics on the cell you’re using. The XP-G2 can have a higher Vf and the cell might have issue giving it equal power. Or, with some of the recent findings on the XM-L2 U3 it could be that one with the higher Vf and it’s producing much more output, which it should be.
So there are variables in the numbers that will show you a lot of what you’re looking to find out.
Look at the charts here that our dear friend Match assembled for us, these should show you a lot … Emitter Test Results
Look at the amperage number of the XM-L2 U3 on copper (assuming you put a copper star in there) and see that it should be making around 1100 lumens at 2.8A. Then check the same 2.8A for the XP-G2 on an aluminum star (assuming this in a stock light) and you’ll see output falling off at 550 lumens.
The tighter hot spot of the smaller die might appear to be equally bright, but the larger die is making twice the output at the same current draw, producing more heat in the process. yes?
Sorry, I’m guilty of transposing the XM-L2 U3 on the stated XM-L U3 used here. Been trying the newest emitters lately and have it on the brain I guess…
Both lights are the same? Only difference is the emitter?
When you zoom into spot mode, the image of the XML should be much bigger than the image of the XPG2. The intensity of the images may be the same so they might have similar throw, but XML’s wider image means you’ll illuminate a larger area.
If both lights are run at the same current, I’d expect the image of the LED in spot mode to be wider with the XML, but the image would be dimmer than the XPG2. Result is the XML would have more flood, but less throw.
As I wanted to test dedoming anyway, I’ve dedomed now both of them. It also appears like both lights are getting equally hot now. It seems to me that the stock wires which were used in the original flashlight were pretty bad.
Now both lights have the same wiring, and both LEDsare dedomed, drivers, heatsinking etc stays the same. I made an amp reading, and both lights were between 2.5A-2.7A.
Dedoming was done using acetone and 2-4 hours waiting. I highly recommend that!!
Here’s an image of the I suspect XP-G2 dedomed:
This is the XML-U3 dedomed:
These are the drivers:
Both heads with LEDs:
“Beamshot” Smartphone just sucks for that, but it doesn’t make sense to buy a camera just for some beamshots . You can see there’s a little bit of glue from the dome left on the left LED
I also went out into the fields to see which distance can be reached with each light. Both seem to have the same brightness now.
Oh, and I’m using: Sony US18650NC1 - 2900mAh, 3,7V Lithium. And here’s a test of them - Credit goes to HKJ from the candlepowerforums.
The green substrate is indeed 1st generation XM-L and the silver substrate is, you guessed it, XM-L2. The XM-L2 should be making ~20% more light from the same current.
Both are on junk aluminum stars. These kind of factory stars have a dielectric layer under the thermal pad, separating the metal pad from the aluminum star. This interferes with the heat flow and causes the emitter to run hotter.
Copper stars with Direct Thermal Path are MUCH more efficient, even at 2.7A. But especially as that current goes up.
aah, shit, I forgot to mention that I modded one of the lights so it now uses the XM-L2. My humble appologies for the confusion :(. To ensure that the previous discussion still makes sense I decided to explain it again in this post:
