Good Morning!
I just got a flashlight with a Cree XHP 70.2 chip (please confirm me if the chip is not fake) and since I am very maniacal and I like to trick everything, I have had some questions.
1- If I paint the interior area, where the LED is allocated, with a paint that has a reflective effect or something, like aluminum foil, and that this paint acts as a reflector, would it increase the output lumens a little more?
2- In the photos of the driver that I attach below, how could I modify it to further increase the output current? Because in my opinion this driver does not take full advantage of the LED. An observation that I have noticed is that the 4 SMD resistors that seem to be in parallel (R750) are the ones that get the hottest in the entire circuit and already have a roasted whole. Is it normal for them to get so hot? My theory is that the autonomy could be much higher because these resistors consume part of the circuit current, correct me if I’m wrong


1: Is there no reflector for the flashlight?

2: You should first measure the current at the LED, then you can decide, if you want to increase it.
How is the flashlight powered? Maybe the batteries cant handle more power draw

Welcome to BLF, eliasklk_04! :partying_face:

The led you are using seems to be a genuine XHP70.2.

If you paint the internal area silver and zoom the flashlight it will project some rings and artifacts in the beam. It may increase the lumen output but most prefer a pitch black interior for an artifact free beam.

The four R750 resistors are the sense resistors that limit the output current. They will get hot because all the current passes through them. If you want to increase the current you need to replace the resistors with lower values or place some new resistors on them. These resistors are needed and can be found on every buck and boost driver to limit the output current.

If Skylight is right and the LED is really a xhp50.2, you can give it as much power as you want, as long as your host has enough cooling potential and your batteries are strong enough. They can be driven at up to 10 Amps (if you have the 6V variant) but they will make a lot of heat then

The flashlight seems to be one of the generic big XHP70 zoom flashlights that are around.

What led me to the conclusion that this is a genuine XHP70.2 is the following:

- No spaces between the dies and regular positioning. Fake leds have large irregular spaces between dies.

- Typical flip chip design with whole led covered with yellow phosphor

  • Circle for plus, square for minus

Judging from the lemon yellow it is a pretty cold white emitter.

My Post was no contradiction, I am just too new to the flashlight comunity, to decide, whether a Chip is original or fake, sorry if I insulted you.
English is also bot my Main language, so this creates even more missunderstandings

You didn’t insult me. I just wanted to tell you some of the criteria to recognize a genuine chip. But I can never be 100% sure, maybe the Chinese reached a new level in faking leds. :wink:

English is not my native language, neither, so welcome to the club. :smiley:

Here is an example of a knock-off XHP70. It is a chinese 7070 led taken from the Haikelite Q30.

In comparison, these are the real XHP70.2:

Thanks for the information, it’s really interresting. Now I should be able to spot a fake xhp chip

Hi to all. The flashlight is the common zoomeable flashlight like the XML-T6 and others. I power it by two 5000 mah Liitokala 26650 batteries in series. Happy to hear that the LED is genuine :slight_smile:
devryd Skylight

My guess is that emitter isn’t being driven that hard since that zoomie would become a great hand warmer in no time if it was. You can swap out the driver depending on the size. It sounds like the 6V version of the XHP70.2, so you might be able to run a FET driver with it for insane power, as it will draw well over 10A. Or get a nice buck driver like Lexel sells.

You can use a online parallel resistor calculator to figure out your total resistance. PARALLEL RESISTOR CALCULATOR
Looks like it has a total of .187 ohms now. Cutting that in half theoretically doubles its current.
I would stack more resistors on top of the existing resistors to lower the resistance and help with the power handling. Adding one R750 on top of each R750 should double the current and double the power handling. There’s other limiting factors like wire, spring and battery resistance that’s not figured in but that should get you close.
Most of the time all the other components can handle the extra power but sometimes they can’t. Depends on the components and how the driver is made.
Its possible it could destroy the driver, just so you know the risk before hand. Usually a slight increase is no problem but there’s always a potential of having to replace the driver. If no one ever tries it though, then we never know.

Hi to all, I will solder today the SMD resistors after few researches that i´ve made. I will post here diferences between original driver and Modded driver. Thanks!

The area around the LED is supposed to be black because otherwise instead of a nice spot meab you end up with something that looks like saturn with a bunch of rings and spill and overall light coming out in every direction.

Hi to all, I´ve made the mod with a SMD 0.5 Ohm and the light output is the same. I´ve even tried with 0 ohms resistance (removing all resistors) and the the output light is exactly the same. I suppose that the driver cannot give more. Can you recommend me a driver that has a good lighting / autonomy ratio? Thank you