M4D M4X wrote:

LinusHofmann wrote:

Fingers crossed!

+1 !

Thanks, looks like it works.

I just ran the new slave in free air with no additional heatsinking and it didn’t throttle back at all even after 2mins @ ~6A! Yay! Pack voltage was around 7.6v in this test which should represent the kind of voltage the slave would have to deal with in the light. Obviously the whole thing got quite hot (over 60degs C ) because the heat had nowhere to go, but no drop in power during that duration so all the chips seem to be getting evenly hot, awesome. Same conditions on the old slaves would see instability and step down after about a minute.

With a fresh pack at 8.4v the slave stepped down after about 20s! Haha lots of energy being burned off there but that’s obvious (I think that’s around 6W of heat being dumped into the poor little slave)!

Ok feeling optimistic that this will work well in the light, let’s get to building the other two

Urgh, 2 down 1 to go. :exmark:

Nearly two hours of squinting through solder fumes to build the second one, is it all worth it?
I certainly hope so…Hah

Probably time to learn how to draw up custom pcbs

Will to live…gone…

But these 7135s are very well sinked now and soldering thermal pathways to the outsides is a piece of cake so getting the heat away from the slaves quickly will be much more easier than before.

Quote:

Looks nice! You’ve got the same amount of .380 chips per emitter as I have in my M6 build. How noticeable was the throttling back before your latest changes? A sudden drop or graduate?

I didn’t notice anything on mine during the hot potato test, but maybe I wasn’t looking close enough (not all that comfortable holding on to a light with this amount of juice for over a minute… yet). I’m not running stacked chips though, and there is a decent bit of space between my driver and the LED shelf.

Have you done the hot potato test?

Well tbh I don’t think you’d see the initial gradual throttling behavior unless your measuring current. I believe the 7135s ramp down output as they approach their ciritical temperature range so it’s hard to tell by eye if the temperatures are at the threshold. If the chips get very hot (120deg C iirc) it seems they’ll try to shut off completely and you’ll notice some flickering and larger instability in the output.

In my experience seeing as you’re running your light off 18650 cells, the voltage sag associated with that power source and the high current draw is probably enough to bring down the amount of energy that needs to be burned off by the 7135s pretty quickly after turn on. You may well be dropping out of regulation well before the 7135s start having a hard time.

I have a fairly hot Apex 5t6 running 20Amps and I don’t think the 7135s are ever taxed too hard even with realtively poor heatsinking, simply because the batteries can’t maintain a high enough voltage for very long.

It’s really a matter of looking at battery specs, taking note of their voltage sag and the vF of the Mt-g2 at that current and hooking up an Ammeter to check your current draw during the test.
If you notice your current dropping out of regulation well before you expect your cells to drop below the vF required to maintain that drive level, then it’s likely the 7135s are getting too hot.

Hot potato isn’t too relevant for me because of the handle, as long as I can keep the 7135s below critical and stop the Mt-g2s from desoldering themselves I should be alright
But tbh I’ll need to really tune in the Turbo timeout to avoid causing damage, this thing gets HOT!

Mike C wrote:

Yeah, I know you have the handle, but would be interesting to know how long it took without using it

Will do when I have the light assembled again.

Boom! Driver puck V2.0

Two copper tabs soldered to each slave provide a solid ground and heatsink connection to the rest of the assembly.

Very pleased with how this came together, took a while but it’s a much much better design than the first attempt. :bigsmile:
Now back to assembling this thing properly!

M4D M4X wrote:

I love it!

Thanks guys

Well guys, this is the moment… first full assembly and test complete! :bigsmile:

(Nearly scorched the faux leather material on the chair taking this shot!)

Haha I’m loving it, this thing is so awesome!
And fortunately everything works as it should, no flickers or wobbles or shorts. Also delighted with the beam profile and tint, just lovely. Was worried I would see some mt-g2 ringyness at the center of the hotspot but the three intersecting beam profiles really hide all of that.

It even handles the heat surprisingly well once fully assembled and with the reflector doing it’s part in sucking some of those joules. I’ll do some runtime tests monitoring temperatures and currents and all that good stuff of course.

It’s not quite done yet though. The reflector I have in there is my spare which has some cosmetic flaws and will eventually be swapped out for a nicer specimen. Didn’t want to risk damaging the good one in a test assembly so this one acted as a guinea pig.

(All emitters nicely centered, happy with that)

You’ll also notice the dark surround on the reflector, that’s something I definitely want to try and get on the final light to give it a bit of a unique look. Fortunately/Unfortunately the approach I tested on this reflector didn’t work as well as I was expecting, the vinyl material I was sticking on was too thick and wouldn’t mold well over the edges of the Oring groove so it left a bright edge and other flaws.
Need to find a method that works before I try it on the good reflector.

Moon mode

—

And yes, beamshots will be happening soon.
First sleep though

lionheart_2281 wrote:

I was thinking more of a “I’ll send you a blank cheque, just write whatever you want on it so long as I get a light like that!”

RaceR86 wrote:

Epic, just epic.

LinusHofmann, while you are at it and have lionheart_2281`s blank check. Just double your amount and send one light to me as well.

Thanks man, appreciate it!

Haha, reminds me of this quote, “First rule in government (or blank check) spending: why build one when you can have two at twice the price?” ( Zemeckis’ Contact ) lol

If you’re serious lionheart_2281 , once I have things finalized I’ll have a little think about what would be feasible.
DavidEF there’s just so much work required on every corner of this light that I don’t think a group buy would do much to the overall cost, but I dunno maybe if a few people are interested.

And because it’s always hilariously awesome, here’s the C8 piggybacked onto the BTU again

..hell just because it’s Christmas… why not a Flashlight on a Flashlight on a Flashlight :bigsmile:

Haha it’s a silly light, my wrist is starting to complain already! Even without all the extra passengers the BTU itself now weighs 1.4kg, not exactly the most ergonomic feature for a handle light haha.
Need to get one of these steadycam rigs for it!

Alrighty, first test results are in.

For now it’s just a full output test versus heatsink temperature to see at what point I should be programming the turbo mode to ramp down.
It’s interesting to see, over the initial 30s there’s the expected turn-on heat sag. Then it’s relatively stable for the next 1.5mins as the hefty mass of the light absorbs the heat. Finally things start gettting a bit too hot overall and the output starts taking a nose dive. This is also the point; right about the 2minute mark, with a heatsink temperature of 50degrees, where the hot potato would be hitting the deck

The light was already slightly warm at 30degs before beginning the test, and ambient temperature was ~22degs C. I would expect better performance outside obviously.
I’ll set turbo timeout to a maximum of 255 (255*0.5/60 = 2.125mins so that’s just about bang on)

What I can’t determine precisely from this test is whether the drop in output after 2 mins is as a result of thermal perfomance drop at the leds or if the 7135s are throttling back because of heat. I’m struggling to get a sturdy enough setup going for measuring current during these tests. Ran out of deans connectors to make a harness so that I don’t drop any extra voltage while measuring.

RaceR86 wrote:

Interesting to see.

I get the impression that output seems to be dropping a lot quicker compared to what the heat sag is responsible for after the 2 minute mark.

Yeah I think you’re right, believe it’s most likely the 7135s ramping down because of heat. But it’s a gradual ramp down rather than the silly flickering and stuttering I was seeing after only a minute with the first iteration driver, so I’m pretty ok with that. In any case I know where to set the turbo step down now

I was also taking note of pack voltage during the test (not on the graph) and that only dropped gradually and linearly from 8.25v (under load) at the start to 8.08v by the end so there should still have been enough voltage overhead to maintain max regulation current. Hard to be sure of that with the light fully assembled though, I could be getting some extra resistance loses that I’m not calculating for.
Should know more when I get a harness made up to splice my ammeter into the situation correctly.

Leaving the light to cool a little (just a minute or so, it’s still >50degs on the outside) and turning it back on returns the output to near the maximum.
Seems to me that’s another indication that the biggest decline in output is related to driver heat.