Help modding dive light

[straycat]

here's some more pics:
https://drive.google.com/file/d/1a5J6hDxwba5p4MnkYNKiA8GdTEtsrAKM/view?usp=sharing
https://drive.google.com/file/d/1_AILDi6ndVZF7fuHKStpP-Aq_O0l8RTd/view?usp=sharing
https://drive.google.com/file/d/1_NkMAvRFqY9XuAAFmIOQMrYwGeUXM2FY/view?usp=sharing
https://drive.google.com/file/d/1CkUQcP0Xvww-aofhSF4ztrucAUHLAo9H/view?usp=sharing
https://drive.google.com/file/d/1skol8sdFx9HX4h97QmLJ5D1LxbeLlrNy/view?usp=sharing
https://drive.google.com/file/d/1a5S79UtWhuqUabMsTY6krUQ6hJMI2jDy/view?usp=sharing
This is the LED in the light presently, it works but, not real bright w/1x26650
https://drive.google.com/file/d/1zIeM_kAiJizWyytVGM4hFFu8-i-7EbOO/view?usp=sharing

 

[DIWdiver]

Okay, now we're getting somewhere. I'm going to guess that the driver is a FET driver. I see no inductor or current sense resistor, and it's definitely not a '7135 driver (pinout is wrong). The part marked 11N06 looks like a PHT11N06 FET, and the part of the circuit that I can see is consistent with this. This is the part that might be mistaken for a '7135, but it's definitely not that.

If correct, what this means is that the LED current is determined by all kinds of factors throughout the light. The voltage of the battery, Vf of the LED, resistance of everything in the circuit (battery, switch, wiring, LED, FET, connections) all factor into the current. And the current determines the brightness.

Running a light like this on 2 LiIon Cells in series would be insane. If it didn't instantly fry the driver, it would cause currents massively higher than the light is designed for. It would be a race to see what component failed first. If the driver sensed the overvoltage and shut down (causing brief flash on the LED), and still survived the high voltage, then kudos to the designers for surviving a potentially catastrophic situation.

In general I would say a FET driver designed for alkaline cells (high resistance) and older LEDs (higher Vf) is probably unsuitable for use with modern LiIon cells (low resistance) and LEDs (low Vf). Both of these upgrades could significantly increase LED current and lead to rapid overheating. However, if you have it working with a 26650 and what I'm guessing is an older LED, and it doesn't seem to be very bright, and especially if it doesn't seem to be getting hot very quickly, you could probably upgrade to a newer LED with lower Vf. This would increase current, light, and heat. It could be quite a dramatic increase, but it's hard to know for sure.

The XML3 compared to the XML has about 0.2V lower Vf at various currents. Since small changes in Vf can result in large changes in current (which is the whole reason we shy away from FET drivers and tend toward CC drivers), this might be enough of an upgrade for you.

That would be my first attempt - replace XML with XML3. If I could make some measurements, I might make a different recommendation, but with the information we have, that's what I would suggest.

 

[straycat]

As I am new to this modding, where can I purchase one of the XML3 preferably MCPCB and exactly what is the part #.
3,6,12,volt?
My existing led MCPCB is 23.2 mm

 

[DIWdiver]

The bare emitter you can get lots of places. I would probably go to Digikey, maybe Mouser.

I'm no expert on buying emitters mounted on MCPCB, but there are a number of places that sell them - Mountain Electronics and LEDSupply come to mind.

 

[straycat]

I purchase a XML3 on mcpcb.
What voltage do I need and any other specs I should be concerned with?

 

[DIWdiver]

I believe the XML3 only comes in 3V version. Make sure you get the color temp and bin that you want. Make sure the MCPCB will fit your light. I think that's about it.

 

[straycat]

Whats a BIN?

 

[DIWdiver]

After they build the LEDs, they test them and sort them into 'bins' (probably not literally) by luminous efficacy. Bins with the higher efficacy will be more expensive. It's usually not a dramatic difference, but it can be more than a little bit. Back in the day when I was building lights, the highest XML bin was U2. R2 was a pretty poor bin.

 

[straycat]

So how do they grade the bins?
I there any logic to it, like 1 is worst than 10 best ?
From your comparison seems like U2 is very good so would U20 be really bad?
Where's the R come in?

 

[DIWdiver]

You have to read the datasheets to find out. There is some logic to it, but you have to know where to start, and what's actually available.

Or, some vendors have enough specs on their websites that you can figure it out.