I’m a complete noob when it comes to flashlights, and this one is bright enough and stuff, but I did some googling after buying it just to find out that there are many counterfeit Cree leds from China.
Just out of curiosity, do you think this is a genuine Cree XM-L2?
Excuse the poor quality of the pic, hope it’s good enough to at least draw some conclusions
I also run a lux test with a friend’s meter (an el cheapo HS1010, so might not be relevant) after removing the lens so that I’m measuring the led’s direct output.
At 1 meter distance I measured some 105 lux. The flashlight runs at 1A on high with a 3.7V 18650 battery. According to the Cree specs, that should translate to some 460 lumens.
Going by Cree’s specs, an XM-L2 should throw at a 125º angle, so at 1m, 125º and 105 lux, no optics involved, the result is about 350 lumens, which seems a bit low
Fake LED or not, that flashlight is not worth $8.40, for a few bucks more you can get a much better light with genuine CREE LED and a proper driver. Convoy S2+ and convoy C8 for example.
Very hard to determine from your picture but that mcpcb seems to be the same ones used to host LB leds.
If you want a better light for your bike just tell us your budget so we can help you out.
I guess I got bit by the flashlight bug LOL. Having a backup light seems good enough an excuse to get a “proper” one, haha, if only to figure out what an actual Cree LED looks like
I got this one because I didn’t want a spotty light, (and it seemed cheap, LOL), and I don’t think 3A drivers on 18650 batteries would last more that 45 mins on a trustfire 18650 batt (2400mAh)?.
Are there any flashlights with 26650 batteries and good flood out there?
What should I be looking for in a driver?
As for my budget, I would say some 30€, give or take
I’m googling “solid pill” as I type, but what do you guys think about the lux - lumen calculation based on the approach I took (no optics involved + claimed angle + measured lux.)? Is it meaningful in any way?
I’m still set on buying a 100% sure Cree quality flashlight. I’ve also recently read that even if mine was a genuine XM-L2, it might be a lower bin led. Boy, is this complex
In your calculation, you are assuming the Cree LED’s light is in a cone with an 125º tip angle. If it is the case, when project it to a wall, you should see a light disk on the wall (or floor). From what I can see from my LEDs, I don’t think it is the case at all. The calculation that you did would not be accurate by any means.
I removed the lens, it was direct light from the LED to the meter. I’m assuming 125º because that’s what Cree rate their leds at. Am I missing something?
I definitely see a uniform disc of light projected, can post a pic if needed
I am certainly interested to see that. Please also make sure the LED is stand alone, i.e., there’s no flashlight case surrounded it. Otherwise, you will see a light disk but the flashlight case will form a reflector and cause the light disk non-uniform.
A better way I think is to check the lux readings from multiple points inside the disk. You can then manually integrate these values and using your lux to lumen conversion formula. If there’s no or very little light outside the disk you should have an accurate lumen value. The only error would be due to reflection loss from the flashlight case, if it indeed behaves as a reflector as I suspected.
Oh, OK, I see what you mean. The led was still installed in the flashlight, I just removed the lens. I guess it was plain stupid on my part to assume that was equivalent to removing all of the the optics.
There’s what seems to be a copper heat sink disk that is probably going to effect reflection, but if I could remove it all, wouldn’t be the lux reading even lower? meaning that it would support the idea that it’s far bellow what a genuine XM-L2 led should be emitting?
Yes it could still be a fake emitter on a solid shelf. But having a solid shelf is a good thing. If it ends of being a fake emitter, you can always get a genuine XM-L2…better yet a XPL-Hi emitter on a Noctigon from here..
However to find out for sure, you’re going to need a macro shot of the emitter so that people here can have a better look at it.
If you are talking about the flash light Ultrafire E17 XM-L2 you mentioned above, I have the same flashlight. No. I was not talking about the aluminum pill. I was concerned about the piece surrounding it (the one with zoom scales). I don’t think it is easy to remove and assume you leave it on. Even if you push it all the way in, it still limits the light so that is why you can see solid light disk. However, if you look carefully, you can see the center is brighter than the ring near the edge. I really think you need to measure multiple points and do integration to calculate the lumen value.
Gotcha. It’s definitely a little brighter in the center, and I used the max lux value for the calculation, which means that actual lumens must be even lower. That seems to suggest that it is indeed a fake LED. I’ll see if I can get a better quality pic anyway.
Good to know I can at least use the flashlight with a new emitter. Thanks once again for all the help and all the suggestions guys
Well, well, well. I’ve been searching for info on that Convoy S2+ and it definitely looks like I wasted my money, LOL. It seems to be plenty floody for my needs and is supposed to go for some $15
I live in Spain tho, and I’m struggling to find it at that price here. It sells for $50 at Amazon! What gives?
