Holy hot stuff Batman, that thing is a portable reflow oven. Glad you found a use for the copper. Let me know if you see anything else in my builds(rare as they are) that you might use.
Trying to follow the logic on how the top of that cell heated up so fast, I think I might be on to something.
I’ve got a spring on the driver, with a 22 Ga wire inside to carry current, right? So this ends up making a point of contact at the cell that is on the very small side. Okay for 6A, but with 15A… maybe not so much! With that much current flowing through a small space what does it do physically to the wire and spring? Heats em up! Immediately!
So I’m going to put a 5/16” diameter brass post on the driver this morning. Far more current carrying capacity and a major contact surface improvement, giving full contact to the top of the cell. That should solve the PTC shut down issue. I’ve already put a solid copper plate at the negative end, with a beefy spring and also wire bypassed…I’ll put a copper top on that spring for a larger flat surface as well. 
The Sony C5 is a flat top, it ran 54 seconds on the light box without shutting down. The button top Efest shut down within 10 seconds. Smaller top plate, smaller contact surface. (granted, the spring with wire soldered in still gives a small surface contact either way) Could simply be that the Sony has higher quality components.
Does that sound right?
Thanks Scott, that copper sheet has been really coming in handy! 
The really thick stuff not as much as the thinner, scissor cut capable sheet. But I’ve used the thicker stuff as well, albeit with some more work getting the piece desired.
Edit: I might even see higher current with the blockages addressed! :bigsmile:
It’s hard to say for certain, and I already mentioned some of this, but here goes:
- HKJ managed to get full 30A discharges out of the ones he tested.
- The PTC responds directly to temperature, not current.
- I think it’s a temp issue, not a current issue.
- The PTC on the Efest may simply be using different materials which change more aggressively with high temperatures.
- I think a battery spacer which blocks the flow of heat from the pill to the battery is what you need. Maybe stainless or maybe delrin/whatever with a 12AWG solid copper wire hammered into the middle.
- If problems persist then maybe your Efest batteries are mildly damaged? Although I thought a PTC was supposed to be tough, repeatable, and difficult to damage by it’s nature.
Ever hold a wire on cell while pulling high current through it? Current IS heat! You can’t have high current through a wire in a transition without some heat, the springs get hot that’s why bypassing their current handling makes it work.
HKJ didn’t test 30A on the cell installed. Big difference. I’m sure his connection wasn’t a pinpoint of solder by spring contact either.
Yes, high temperature causes the polymer to cease being electrically conductive. The design is to protect against a short circuit, high current-high heat-shutdown. After cooling the physical properties of the polymer switch are supposed to go back to normal and continue being electrically conductive again, according to experts that put together a paper from Cambridge, NASA and YALE.
At any rate, putting the solid brass contact in place of the spring was one too many times working on it. It’s DIW.
I realize that a high-resistance path (such as a small contact point) generates heat. I’m a little frustrated that you find the need to mention all that again. OTOH I suppose it’s only fair since I was repeating myself as well.
It’s your light: if you’re happy with it on the Sony cell then there’s certainly no need to ‘fix’ the light’s behavior with the Efest cell.
Working again, soldering on the brass post caused the diode to lose contact on one leg opposite the battery contact.
I mentioned it again for 2 reasons, one to be sure I was understanding it correctly and 2 this is an open conversation that others with as little understanding as myself can get it.
And besides, isn’t the actual pcb of the driver a FR G10 laminate? Doesn’t this separate the battery contact from the pill? Isn’t most of the heat brought through at the contact point itself, regardless of being surrounded by FR G10 or Delrin or whatever?
I don’t know these things, just going on reasoning and what little common sense I have left to me…
All fair enough. I agree, it seems that most of the heat must be finding it’s way back through the positive contact… or the battery tube?
I’m not really certain what the best way to block the heat transfer is. A stainless steel spacer might be an OK option, assuming that the heat is coming through the positive terminal.
I had it too tight with a beefy tail spring and the glass lens broke. Cutting a UCLp down to fit, then I’ll see what the Efest cell does on it with the brass contact.
Had to come in, cordless drill battery died and my backup wasn’t charged, go figure.
Efest 35A runs 15.10A at start, fresh off the charger. It’s down to 14.10A at 36 seconds and the head of the light was uncomfortable to hold onto. Stuck the cell back in the charger, showing 4.06V.
Little power hungry beastie is what it is! The FET on this A17DD-S08 performs just fine, both it and the MCU now have a thermal pad on top of em.
I find it amazing that a single cell can run that kind of power. Crazy stuff. And I love it!
Thanks Wight for a job well done with this driver! This will be a staple for me now, the single sided layout is just so much easier to build and install.
Edit: might should mention that in all the rebuilding and messing with this light, 2 of the 4 XP-L’s have become de-domed…one was mysteriously so and the other had a loosened dome that I pulled off with my fingernail. Lucky that they oppose each other on the board so it looks ok.
Edit II: Cell recharged, 4416 lumens at start, 3743 at 30 seconds. Efest 35A works fine now.
Thanks for the complements and for keeping us up to date. I’m glad that the Efest is playing nicely now. So do we think it turned out to be contact resistance after all? (eg the heat from high current across high contact resistance was tripping the PTC?)
I addressed multiple issues by putting thermal pads on both the MCU and MOSFET, and also gave that larger contact point for the cell. The combination works, not sure if any one would have done it stand-alone.
This host is really a bad choice for this, as it has poor head-to-heat sink contact and no cooling fins at all. I’m thinking of using a mix of JBWeld and copper sanding dust to fill in around the copper heat sink in the head, there’s enough space for a 22ga Silicone coated wire to fit all the way around from about 1/4” up from the base of the heat sink…so a little more than 3/4” of the heat sink has no host contact. I really should have used a larger diameter copper bar to start with and totally filled the head, but I used what I had.
This design puts all the thermal path contact right down there at the driver, no contact anywhere else.
@ DBCstm - I’ve been thinking of getting one of those PH-08. Maybe to build a triple in since I have no quad MPCB’s. I do have a lathe, so the pill isn’t the end of the world to me as long as there is a nice cylindrical area to interface with. Knowing that, would you recommend something else in the price bracket?
In the meantime:
I’ve created a new derivative driver from this project, eliminating the Zener in favor of an LDO with a much lower parasitic drain: 17mm++ single-sided / DD driver w/ low parasitic drain for e-switch lights: AxxDD-SO8+LDO
A17DD-SO8+LDO
FastTech has this one for around $11, don’t know that they can be had much cheaper. This one is kind of an odd duck, but for some reason I like it. It’s not any bigger than it has to be, has some mass in the head albeit not a lot, the only thing I can think of as a true con is that…on mine…the tail threads are sorta weak. They’re not very deep and the tail cap is a bit oversized so it’s not a good solid threaded fit. Mine’s an older one though, so maybe they’ve gotten a little better.
I had a few Quad optics and boards and the 24mm size fit this one perfect, so I used it. It’d do good as a triple, there’d just be some space around the lens with the 20mm optics.
My 7 yr old just decided the PH-08 is a heat lamp and started singing a song about it. Crazy kid…
I wrapped the copper heat sink with an appropriate ga bare copper solid wire and sealed it at the top (between the star and host) with Arctic Alumina Thermal Adhesive. The heat goes into the full head now, but while it does ok for the first 30 seconds or so by the time it’s hitting 50 seconds you can feel the heat (head only) really cranking up. At 55 seconds it’s about to leave burns on the hand. (Edit: I guess it’s safe to say that if it were turned on to the highest level and laid down, left alone, it would self destruct in a fairly quick manner)
Serious amount of light coming from a very small source. The 2 domed and 2 de-domed XP-L V6 2C gives a nice neutral/slightly warm tint and is nicer than I expected.
The driver, with ToyKeepers ramping firmware, will make a bit of song at certain levels but it seems to be more during ramping than when sitting on a level. With 64 levels there’s a decent place to stop it pretty much whatever the need. Really like it, very useful light and easily maintained at decently high levels without getting crazy hot.
Edit II: Further testing (and some assistance from younger ears) proves out that the singing is done just below max level. Silent at max though. Then it quiets down toward medium levels and is silent on the lower levels.
Heh, I have placed on in my cart at FT to “think about.”
Did you build it with fast PWM or phase-correct? It’ll make sound with phase-correct, but shouldn’t be audible with fast PWM.
BTW, the Roche F6 is a nicer-quality host than the PH-08, and with Comfychair’s driver it also provides battery indicator lights. I really really like mine. I don’t think a quad would fit though; IIRC it’s a bit smaller.
Dale - on the PH-08, do you find the button is pretty stiff? Is it a hard rubber? I got two XP-11's from WallBuys that seem to be the same exact light with a hard rubber button cover. Weird brass pill that sort of fits snugly into the body with no threads? I know you replaced the pill though... After some usage and time with them, I prefer the Small Sun's of a comparable size with the e-switch, basically same cost, ZY-T11 or ZY-T29 with the alum reflector.
One of my XP-11's side switch had a short, couldn't see how to get the rubber cover off, so ended up ripping it. I repaired the short on the switch, but now it's switch is exposed - not too water resistant... Tried gluing the button back, seemed to work for a while but didn't hold up with usage.
I used phase correct, knowing it might sing a little but I don’t mind. I wanted the 64 position ramp so went with the phase correct.
Yes, the button is pretty firm on this e-switch…I consider that a good thing because it won’t accidentally turn on very easy. I built a Small Sun ZY-T29 and was using these 2 side by side with single emitters. The build quality is probably a bit nicer on the Small Sun but for some reason I like this PH-08 quite a lot. Gave the Small Sun to my mom with a reversing UI.
If I was buying a light to do a mod like this I might would get the Small Sun ZY-T29, it just happened that I had this one sitting here when I was looking for something that would be a likely candidate for a quad that I could try wights driver out on. And it also just so happened that I had a 3/4” bar of copper sitting here that I’d gotten months ago for a project I canned. AND it just so happened that the machined sleeved area that the PH-08’s brass pill slides into easily accepted that 3/4” bar with just a light touch from some sandpaper.
I get lucky far more often than I should, I know. Someone upstairs has my back, which is really good, because my front is very faulty…
Thanks ToyKeeper, I’ll have to mull this over.
I’m getting a PH-08 eventually for a project, so I should be able to post comparison pics then. However, shipping from China (and everywhere else) is now in crazy-holiday mode so it might be a long time before anything arrives. Comfychair’s thread on Roche F6 hacking provides lots and lots of details though, if you’re curious.