i modded a BJ08A recently with a triple XP-E2 (parallel board and XP-E2s from IS). The pill is such that the original emitter was sitting kind of deep in the pill, and right now, I just have the emitter PCB sitting on the edges of the pill, with thermal compound around the edge. I haven’t filled in the “hole” where the original emitter was yet, as just getting started.
I have a stock 2.8 amp 105C driver in it, and it works fine.
However, if it’s left on high, and obviously gets hot, I’ve had one of the leads to the emitter PCB detach itself, probably because the solder holding the lead to the pad just melts :(… The solder pads on this board are TINY, so it’s tough to get a good joint.
I’m thinking of filling in the hole, maybe with Fujik, or maybe with copper wire and solder, but was wondering if, for a triple, where the emitters are on the perimeter of the PCB, is there something different about doing heat sinking?
Normally, on a single emitter PCB, the heat source is in the middle of the PCB, but with a triple, it’s at 3 places near the edge of the board, right?
I made a metal disc that fit into the hole where the emitter board used to go into and press-fitted it into the hole, so now the triple emitter PCB should be sitting on metal entirely. Then I put some thermal compound on that and re-assembled the light. Hopefully, that’ll work ok now, and won’t be melting the solder joints :)…
If you still have problems, OL did a post where he used copper shot to add some mass behind the PCB (limited by driver height). That or some solid mass might be needed with triple the heat!
Can you grind down the perimeter of the pill to make the whole thing flat?
You want as few layers as possible between the LED and the main heatsinking surface. Filling in the space won’t be as good as eliminating the space altogether.
The BJ08A pill is a little unusual. I has 2 sections that have threads on the outside, and the driver goes into one of them, and originally, the emitter went into the other. The body/battery tube screws onto the threads on one section, and the head screws onto the threads on the front section. So, if I were to file down that front section, the head would have any way to screw onto the pill.
I’ll be doing some extended testing with high mode and if the emitter-lead-to-solder pad joint pops off, I may try that, or something similar (I was thinking of adding some pieces of 14AWG wire inside the pill and then solder).
Cut out the center of the pill so there's nothing left but a tube with threads on the OD, press in a chunk of 5/8" copper bar stock. On most lights the optics will be shorter than the reflector so the copper bar lets you move the star forward while keeping the driver in the original location. That's how I'm doing the Convoy S2 & S3 for the Noctigon triples (if packages ever start leaving the Far East again anytime this decade, that is).
Thanks for the link to the copper bar. I may try that also, if the testing I’m doing now doesn’t work out.
I’ve already tried several 3 minute runs on high, banging the light around (gently) to see if the solder joints might’ve melted, but so far, so good.
By about 2 minutes the entire body of the BJ08A (this is a 1xAA light) gets almost too hot to hold… by 3 minutes it IS too hot to hold.
I’ve been thinking that I might try switching from the IS triple PCB to one of the Noctigon triples (should be an easy swap - just desolder the XP-E2s and reflow them onto the Noctigon, and then solder on leads), but am waiting for results from you all on that other Noctigon triple thread. I’m also waiting until I have more stuff that I’d want to order from IOS so that I’m not ordering just the Noctigon triple boards.
EDIT: FYI, with the board sitting on the front of the BJ08A pill like it is now, it fits perfectly with the IS triple board, the Carclo 10507 optics, and original O-ring. I don’t use the original lens (it’s not in the light).
5/8" aluminum bar stock is an option considering the threads would still be crappy brass, but yet be so, so much easier to machine. But copper & brass can be soldered, AL would have to be more precise and rely on only a press fit which would have to be really tight, as screwing the pill in will try to push the bar stock rearward in the pill.
If the stack height is close to what it was with the original reflector and you don't need to extend the mounting surface forward, a copper disc to fill in the 16mm pocket would perform just as well.