Modding dive light question

Thats definitely not a FET direct drive circuit.
Curious, Have you tried running the stock light with either the OEM or swapped-in emitter but using a single 26650 and a dummy “cell” to bridge the gap? If it works in that scenario, I would expect it to work fine with a 3V 50.2.

Thought about it a little further… A good 26650 IMR can pass WAY (!!) more current than 3xC alkaline. So on paper theres potential here for a significant increase in brightness. But then again it all depends on that driver and all the current limiting resistors. That stack of springs also looks like it could limit current. And we still know nothing about the switch itself.

FWIW I dont think any of the LEDs you posted are 12V.

Mmmm, I’m pretty sure those aren’t ballast resistors, but like I said, bleeder resistors. Ie, they’re in parallel with the LED to let modest current through without the LED’s voltage-drop.

When the driver’s in the tail, it can’t get power directly from the cells when powering the LED. So it turns off the LED for brief pulses, maybe 1–2 or so, so that now it’s the load, and sees full battery voltage minus the small IR drop across those 2 resistors (look like 200Ω in parallel, so 100Ω total).

That current spike gets stored in a small cap just long enough for the µC to do its thing ’til the next turn-off.

Trying to ignore the glare from the light, it certainly looks like those resistors are right in parallel across the LED.

But without having Big-Clive-type breakdowns and schematics, there’s no way to be positively sure. 95% or so, sure, but not 100%. I’ll still take those odds.

Point being, if that’s indeed the case, the existing driver and contact board ain’t going anywhere. Only the LED can be swapped, and I doubt that’d buy much.

The original led burned out when I put 2 x 26650 in series.
The one in the pic is from a friend and it does work with 1x 26650 but lumens are low like approx 500
The “12 volt??” led that a freind gave me to try with 2x 26650s was real bright probably 2000 Lumens , but the tailswitch wold not turn it on. so we had to run a wire from the last 26650 to the outer shell of the light.
I have good unprotected 26650’s

I understand that this mod is probably not cost effective, but I just got into flashlights as a hobby and would like to learn more about the inner workings. This light is something to play with/ take apart/modify.
I probably will purchase the Sofirn SD05 light you recommend as it seems as good as my primary dive light: Wurkkos DL-40

Taking the light apart is no problem, it’s the posting of pictures on the site I have problems with.
How does “clientequator” have the pictures show on the forum, where mine are only links?

That whole goggle-drive thing. Tried rightclicking on the image to view directly, nope, won’t let me.

Imgur is worse, and sucks bigtime. Half the time I don’t even see embedded imgur pix, and clicking on them and going on the actual imgur page just nets me a blank dark-gray page with header, but no pic. And that’s on my ancient laptop here and the way more modern one at work.

If you wanna display a pic, like this

You’d either use the bang notation


or actual tagging

<img src="">

Where to get the url of the pic? Well, that’s something else…

Usually rightclicking on the image can get it, select [view image] then grab the url, but some asshat sites disable that nicety.

Should be easier.
Other forums I am on it’s real easy

It is just as easy here… I just click the image button and enter the URL.

Yep or just paste the image URL link address and add an exclamation point immediately in front and behind.

Yeh, that’s bang notation, but if there’s anything immediately after (eg, the close-quote tag), then the quote will display with the url and not the pix, so I go through the extra “trouble” to put the actual image-tag.

RC has a thread about how to post pictures

I tried that 2 x no luck , URL from google drive


I give!


A display page is not an image.

Well, you got the pics, not in the format I would like to see, so lets address the original question.