BTU Shocker Triple MT-G2 with a twist -- Aiming for >100Watt ~9000Lumens -- With external 2S power pack, handle etc...

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blueb8llz
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This was and is a very enjoyable read. Job extremely well done. Looking forward to beam shots!

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Well done! Bravo!

~ Ledsmoke ~

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LinusHofmann
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Quote:
This was and is a very enjoyable read. Job extremely well done. Looking forward to beam shots!
Quote:
Well done! Bravo!

Thanks guys Smile

MRsDNF wrote:

I cant find where you said you current draw was. In djozz’s graph I can confirm my measurements were close to this. Post 16.

http://budgetlightforum.com/node/22636#comment-417559

If you take away a conservative 10% in losses could it still be a voltage issue? Can you stick the probes on a single led without the reflector installed without blinding yourself?

Max drive current should be 5.84A x 3 = 17.52Amps (I was lazy and used the 8× 0.350A 7135s already on the boards and added 8× 0.380A ones so total current is a bit lower than the first set of drivers which had 16x of the higher binned chips)

I was also using djozz’s great graph and it seemed to measure out correctly for me when I verified voltage across the emitters at 6Amps.
I was using ~7v as a minimum target voltage to feed to the drivers while still maintaining regulation (think I verified 6.9v at the leds @ 6Amps). So I have faith that the basic calculations are near enough correct.

I know I drop around 0.6v by the time the cable plugs into the back of the light including connector losses and I was using a 0.2v drop across the 7135s. What I didn’t get round to measuring was how much I drop across my twisty contact interface going into the driver contact board. That’s the last place where I would imagine larger losses are to be found, unfortunately I didn’t have access to the resistor array dummy load and 1000w psu that I used to test for resistance losses within the rest of the system.

So, starting with an 8.25v battery voltage (under full load) I should have a vF overhead of 8.25 – 0.6 – 0.2 – 6.9vF = 0.55v

—-

Here’s the same graph with pack voltage included. It’s still well above 8V at the end when output has collapsed down to 50klux. And again, turning the light off for a bit then on again the pack voltage will return to that same level but output will be up near 70klux again. Can’t explain why that would happen if the pack voltage was inherently too low to maintain that level of output right?

Urgh I dunno, I’d be rather surprised if the voltage was limiting output this drastically but I may still have some extra resistance losses eating into my overhead.

I’ll need to get some accurate current measurements to figure out what is going on. I did do a test with my crappy harness but that was dropping 0.36v before it even left the battery pack and ammeter so that’s a bad test setup. Max drive current I saw in that test was still 16.7A though and it held it up for 1.5minutes fairly steady before again starting to drop off more quickly.

—————-

At the end of the day it’s a bit of a catch 22 with these linear drivers. Especially with a battery pack like this which doesn’t really sag.

If I improve resistance losses and get a higher voltage to the drivers

  • Theoretical longer time in regulation
  • More energy for the 7135s to burn off
  • Possibly getting 7135 overheat, throttling and flicker earlier negating the extra regulation time. Silly
LinusHofmann
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Well I’ve been having fun with graphs again.

To check whether my thoughts in my last post where correct I did another test. This time eliminating the battery pack and cable entirely, plugging the two packs across a reinforced harness and directly into the light. I also rigged up my hefty power meter to measure current.

Here’s my test setup

And the balance board reinforcements I needed to make to reduce resistance losses to a minimum

This way (by eliminating the resistance loses across the spiral cable and relays in the pack) I am verifiably gaining 0.6v in voltage overhead compared to the fully assembled light. That should eliminate any concerns that the voltage is dropping too low and causing the sag in output/regulation.

The test was carried out in two parts.

1. I ran the light on high from cold taking Battery Pack voltage, Battery Current, Lux, and Heatsink Temperature readings every 30 seconds.
2. After 6mins I turned the light off and let it cool down for around 5 mins.
3. Then I ran the light again for another 3 minutes taking all the measurements again.

So here’s the graph.

It’s quite interesting, and I think it verifies quite nicely my thoughts that driver heat is the primary cause of the drastic output drop overall, but especially after about the 2minute mark.
In fact with the higher voltage reaching the driver this time, I see a less stable regulation phase initially that drops more quickly and more steadily than with the fully assembled light. Last time between 1:00 and 1:30 I saw a flat spot in output (indicates decent regulation), this time it’s all downhill from the start.
After the 2 minute mark again output takes a nose dive. And this time it took only 4 minutes before the output had collapsed to 50klux while on the fully assembled light it took a minute longer to drop to the same level.

The voltage gradually drops as expected during the test but the crucial bit regarding this aspect of the situation happens after the cooldown period.
At the 6minute mark battery voltage under load was 8.08v, during the cool-off period with the light off it recovers up to 8.15v however crucially upon turning the light back on for the next part of the test it is bang on again at 8.08v.

As a result the output and current readings taken right after the light is turned back on can be compared directly to the ones taken before the cooloff period. With battery voltage being bang on identical between these two points the only variable to blame for the massive difference in output/current draw has to be heat. Aha!

You can also see that with the lower battery voltage at this point, the driver actually has more of a chance to try and regulate current and there is even an increase in driver current and output a minute after the restart. Unfortunately it doesn’t last long before the sharp drop once again kicks in.

Finally, having the current readings and seeing them track pretty neatly with the output measurements rules out thermal deterioration at the leds being the primary cause of output sag.

My conclusion is that the driver assembly is choking on it’s own heat and can’t shift it away quick enough, as a result it drops output prematurely.
It’s probably just keeping up while the temperature of the pill is below 50degress, but once it’s environment has reached that temperature and beyond it’s a losing battle and things start getting really toasty quickly.

I will try to do something to maximize thermal contact between the aluminium driver assembly and the walls of the pill. Maybe by stuffing some aluminium foil in there are and applying a bit of thermal grease. In any case I’ll redo this test to see if it has made any noticeable difference at all, suspect it won’t do all that much but it’s worth a try.
There’s just too much heat involved here, liquid nitrogen might be the only solution Smile

Next one of these will have a copper slug sinking those 7135s! Or a bunch of ventilation holes and a blower fan keeping things in check :bigsmile:

If anyone has any thoughts on this dataset it’d be appreciated, hopefully I’m interpreting the data correctly and not barking up the wrong tree here.
Cheers

MRsDNF
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Nice testing LH. I wonder how a small fan blowing on it would go to simulate the light being taken for a walk?

 

djozz quotes, "it came with chinese lettering that is chinese to me".

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LinusHofmann
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MRsDNF wrote:

Nice testing LH. I wonder how a small fan blowing on it would go to simulate the light being taken for a walk?

Not a bad idea, how about two? Wink

Does BTU actually stand for “Bi-Turbo Unit”?? :bigsmile:

lionheart_2281
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This light just keeps looking better and better!
I know it’s just a concept, but hot damn that’s awesome

Ervin Anastasi
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i was pretty sure heat generated from amc was the problem. they have some sort of self protecting thing regarding temperature . when u push hard them and they cant radiate enough heat, u could have than all sorts of exotic problems in output. in one of my projects one stack with amc start to periodically change output for example. apart from this little problem everything looks cool on your project and i am enjoining the investigative part of your project with graph and so, even more.
seeing all this new projects and cool works that is being done around here, is starting to awake my sleeping appetite for projects.

usually its hard to realize how complex similar projects can be and how much work and effort they require. thank you for your effort and for sharing this.

some of my actual experiments and reviews:
UF-T20 review and mod —->http://budgetlightforum.com/node/30186#node-30186
My EBRZM, over 1 million cd thrower—-> http://budgetlightforum.com/node/30274#node-30274
Ervin’s try (2nd. Annual BLF Scratch Made L

zelee
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LinusHofmann wrote:
MRsDNF wrote:

Nice testing LH. I wonder how a small fan blowing on it would go to simulate the light being taken for a walk?

Not a bad idea, how about two? Wink

Does BTU actually stand for “Bi-Turbo Unit”?? :bigsmile:

make it liquid cooled version Wink

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LinusHofmann
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zelee wrote:

make it liquid cooled version Wink

I do like the potential or these new integrated water cooling solutions don’t see a way of making it work here though. Maybe someone else can build/modify a light around something like that, be cool to see.

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i always “ shoooh! “ my thoughts away when a liquid cooled Light comes into my mind.

(un)fortunately i don´t have access to a lathe and a mill…

 

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kronological
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I just caught up on this after a few months…WOW!

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LinusHofmann
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M4D M4X wrote:
i always “ shoooh! “ my thoughts away when a liquid cooled Light comes into my mind. (un)fortunately i don´t have access to a lathe and a mill…

Yeah it’s not gonna happen here, best thing I can try is something like that concept with a blower a form of duct that directs the airflow around and over as much of the limited fin area as possible. Think it could work and I have a couple of those fans on order to give it a go.

Fan noise is pretty lame though, so not sure how much use something like this would actually get, if nothing else it would at least look cool and act as an anti roll aid. Can’t have this thing flopped on it’s side or sitting on it’s face and hiding those lovely emitters when it’s sitting on the shelf now can we. Smile

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DIWdivers 13.5 amp linear driver may be of interest to you. It is fully dimmable via potentiometer. There are also 10, 8, and 5 amp variants.

Very clean mod btw. I like it. Party

LinusHofmann
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Hoop wrote:
DIWdivers 13.5 amp linear driver may be of interest to you. It is fully dimmable via potentiometer. There are also 10, 8, and 5 amp variants.

Very clean mod btw. I like it. Party

Thanks, I didn’t know about that option.
Tbh I like having a standard clicky ui on a light like this (with all the nice firmware options that this hacked up 7135 driver offers), but there’s something to be said for a nice clunky multi position pot switch or dimmer combined with a driver like that. Bit more old school.

Tempted to find a use for it somewhere now. I’m also fond of the predictability of linear drivers, every time I play around with switching boost or buck drivers something usually ends up smoking…haha Wink

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Well I asked Ric about his BTU shocker stock and apart from a few battery carriers and switch boots he’s completely cleaned out. Until I asked him the BTU kit (no driver) was still on the webpage, looked like it was still in stock and available for a good price, now that’s gone too.
Looks like this is the end of the shocker. Sad
I did ask about another possible production run but he didn’t get back to me on that yet.

FmC
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LinusHofmann wrote:
…… but he didn’t get back to me on that yet.

lol – don’t hold your breath.

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LinusHofmann wrote:
Well I asked Ric about his BTU shocker stock and apart from a few battery carriers and switch boots he’s completely cleaned out. Until I asked him the BTU kit (no driver) was still on the webpage, looked like it was still in stock and available for a good price, now that’s gone too. Looks like this is the end of the shocker. Sad I did ask about another possible production run but he didn’t get back to me on that yet.

Don’t give up mate! PM Vinh on the other forum, he has rooms of spare parts! Perhaps slight exaggeration!

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Alright, hope everyone had a good break over the holidays!

Still no beamshots I’m afraid, we have half a meter of snow outside so those will have to wait a bit.

-

I’ve got some new super exciting runtime graphs though! Yay! Wink Silly

I had a go at maximizing the heatsink stuff inside the driver cavity and then ran the same setup as the last test to see if I could see any difference in the output behaviour.
All I really did was wedge some bits of thin aluminium sheet in between the driver assembly and the cavity wall, press some TEM cubes into the middle of the 7135 slaves (just to try and homogonize the temperature within all those 7135s) and apply a bit of thermal paste where needed.

I also touched up a solder joint on one chip that looked suspect and could potentially have caused a flicker on one particular emitter. That was something slightly annoying I noticed each time the light was warming up. I probably didn’t solder one 7135 ground tab perfectly with the copper sink rings causing it to heat up faster than all the others.
Not sure yet if that has been fixed but I definitely hope so.


It’s a mess in there and I wasn’t too hopeful that it would actually do all that much but the test results are pretty significant!

( Faded graph is old comparison test done before the heatsink improvements, solid is the new test. )

Everything was set up the exact same way as the first test except that the starting temperature of the light was around 4 degrees C cooler.

So I’m very pleased with these improvements. It’s really obvious that the light is now able to maintain considerably higher output for longer, the steeper part of the output curve now starts at 4.5mins rather than at 2. Temperature on the outside of the light also gets considerably higher and continues on towards 70 degrees, at around the 5.5 minute mark I saw a larger flicker in the output and decided to call it a day at that point! Haha, made me jump a bit tbh! Silly
I suspect that was caused by one entire driver puck getting too hot and calling it quits, didn’t investigate which one because I wasn’t too happy running the light at that kind of temperature.

Next I’ll do a test with the battery pack cable again and see what real world performance looks like now.
Seeing how much better things are running now, I may well go back in and pot the entire driver assembly.

Cheers
Linus

MRsDNF
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You gotta love that temp line. Smile

 

djozz quotes, "it came with chinese lettering that is chinese to me".

                      "My man mousehole needs one too"

old4570 said "I'm not an expert , so don't suffer from any such technical restrictions".

Old-Lumens. Highly admired and cherished member of Budget Light Forum. 11.5.2011 - 20.12.16. RIP.

 

LinusHofmann
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MRsDNF wrote:

You gotta love that temp line. Smile

Haha there’s no stopping that bugger! If I keep tweaking I might just get it vertical! Wink

But to be fair I’m loving the waft of nicely heated air rising up to my hand on the comfy cool handle! Only need to bring one glove out in the snow. 8)

Edit: Dammit, the flicker is still there. Number 1. driver/emitter (top center) is the culprit, my re soldering didn’t do the trick. Really hope I don’t have to take everything apart again…urgh…
I’m really starting to hate these 7135s! Sad

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Test done with fully assembled light, (no current measurements for sake of seeing real world output performance)

…too tired to really figure out what’s going on but I’m a bit surprised. Is driver heat STILL the dominating factor dropping performance or does pack voltage now come more into play?

You can see the two output lines are perfectly parallel for a small section of the test, the cable setup a bit lower output (are we seeing the 0.6v cable losses?) but not much resembling a regulation phase before that. Just a bigger collapse in output over the first 1.5minutes.

LinusHofmann
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Aha! Think I’m onto something here, environmental cooling system! Bet you wish you had this type of thing down in Aus ey MRsDNF? Wink

Not the most portable system but very effective! 8)

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The driver issues have driven him insane! J)

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DavidEF wrote:
The driver issues have driven him insane! J)

Certainly seems that way, I must have truly gone insane to drown my entire driver assembly in fujik!
…what have I done…. seriously hope it helps! Silly


It looks like the worst kind of chinese assembly line practices in there! Wink

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I just got back up to speed on this (I was ~79 posts behind…). Lots of impressive work. The new driver stacks look great, big improvement. >16W through those 7135’s sure is tearing stuff up. Your graphs are great and informative.

LinusHofmann wrote:
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 Wink But tbh I’ll need to really tune in the Turbo timeout to avoid causing damage, this thing gets HOT!
Don’t forget the risk of an accidental hot dedome.

MRsDNF wrote:
Can you stick the probes on a single led without the reflector installed without blinding yourself?
It’s best to solder an extra pair of wires onto the emitter MCPCB and bring them off to a test point on the side. I’m not saying I always do this (I do not always do this.) but it’s much safer for both the operator and the $20 LED.

LinusHofmann wrote:
Edit: Dammit, the flicker is still there. Number 1. driver/emitter (top center) is the culprit, my re soldering didn’t do the trick. Really hope I don’t have to take everything apart again…urgh…
I’m really starting to hate these 7135s! Sad
Don’t hate me<ducks>, but I’d better suggest the standard troubleshooting step: swap emitters between two driver sections. Flickering at high currents could be caused by damaged bonds in the emitter itself.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

LinusHofmann
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wight wrote:
Don’t hate me<ducks>, but I’d better suggest the standard troubleshooting step: swap emitters between two driver sections. Flickering at high currents could be caused by damaged bonds in the emitter itself.

Hmm, good point I hadn’t thought of that.
I have some heavy welding glass, maybe I can watch the emitter closely while it happens to make sure there aren’t specific sections of the array going offline. It certainly seemed like behavior I’ve come to expect from a single 7135 chip going toasty but I’ll investigate.

It’s not a tragic problem, not really noticeable during normal operation but still a little annoying if I can’t get rid of it. The emitter isn’t losing a lot of output, it’s really just a small drop in brightness that starts with a twitch or flicker and then seems to stay at the lower level from then on. My power meter isn’t quite granular enough in it’s current reading to show exactly by how much the current drops during the flicker but gut feeling is I’m losing about 0.380ma of brightness… Silly

Similar stuff happens later at a much greater extent when the other drivers reach critical temperatures.

-

First I’m hopeful that my fujik drench did something to help the situation, if not I’ll have to see further. Frankly I’d be much happier to find a dodgy emitter at this stage than the thought of having to dig out and disassemble the whole driver assembly! |( :_(

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Now that you mention welding glass that stirs my memory. IIRC another BLF member had a failing MT-G2 they viewed under welding glass. Probably DBCstm. Ah yes, here we are:

  1. - http://budgetlightforum.com/node/33066?page=13#comment-635770
  2. - http://budgetlightforum.com/node/33066?page=13#comment-635788

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

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wight wrote:
Now that you mention welding glass that stirs my memory. IIRC another BLF member had a failing MT-G2 they viewed under welding glass. Probably DBCstm. Ah yes, here we are:
  1. - http://budgetlightforum.com/node/33066?page=13#comment-635770
  2. - http://budgetlightforum.com/node/33066?page=13#comment-635788

Damn that’s crazy, I didn’t know they did that. Never had an emitter fail on me before so I didn’t even consider it.
I’m really curious now to take a look at the emitter at full power to see what’s going on there.
I did have to reflow one of these emitters back when I got them, but checking back on photos there’s no correlation to the troublesome emitter.

I wonder if this might also explain some of the strange current draws I’m seeing, never quite getting up to where I expect them to be even with what I consider plenty of voltage overhead. Maybe the 7135s aren’t completely to blame after all, we’ll see if they can redeem themselves. Smile

Cheers for the heads up!
Linus

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Ok, here are the final results after the fujik potting.

The graph is a bit of a mess because I overlaid the first two no-cable tests to show the direct differences that upgrading the driver heatsinking has made.

I’m glad to see that potting in fujik has shown another improvement, more subtle this time but still a worthwhile improvement resulting in a flatter overall current/output plot. Particularly obvious after the 3.5 minute mark where current seems better regulated (why it jumps up suddenly I have no idea, but I’ll take it!) and output is considerably higher than before as a result. The output heat cliff is pushed further back and is now very close to my 70degree temperature cutoff on the heat sink. When I called it a day at 5.5minutes I was still seeing 16.31 Amps draw. Nice!

Output heat sag at the emitters is obviously also a factor in all this, but even without considering the drop in current from the start of the test I’m only seeing about a 15% drop in lux over the course of the test. That’s pretty acceptable to me considering the exceptionally high power levels we’re talking about here.

I also tried to repeat the cool off and retest method of the very first test to see how things compare. I failed to get the light back to the same temperature but pack voltage and output was very similar. Actually they track amazingly well just after the turn on and even with a higher overall starting temperature it’s obvious that performance is maintained far better than before.

-

Overall I’m pretty pleased with the output characteristic of the light now. I still need to see how things have changed in the fully assembled light but this gives me confidence that the driver heatsinking related performance is now about as good as I can get it. Anything I can do to improve resistance losses from here will likely result mostly in higher output.

-

Unfortunately the bloody flicker is still present, it seems to start right around the 2.5 minute mark and looking closely at the offending emitter through the welding glass I see nothing at all dodgy with it. All array tiles are fully lit, very even and frankly I can’t directly see any flicker at all while looking at the emitter this way. It’s only really obvious when shining at a white wall and covering the other two reflector wells with my hand, it’s the kind of thing you catch in your peripheral vision more than when directly looking at the hotspot.

Well I was hoping it was the emitter that was obviously at fault, it might still be but if so only in a subtle way, maybe it will get worse and become more clear as the light is run in?

I think it’s most likely that I damaged a 7135 chip in the stacking process, either through bending the legs (not recommend I know but had to be done) or through applying too much heat. It may even heat up, flicker, go offline completely and then flicker back online as the overall temperature gets higher. Possibly a stretch but it might just explain the jump in drive current I see around the 3.5minute mark… Flat Stare

I dunno it’s too complicated with all these chips, trying to keep track of all the variables is doing my head in. The 7135s are probably all going through varying degrees of not working 100% right at these temperatures and all I’m seeing is the sum total if their combined agony! Silly
I don’t really want to desolder the emitter wiring to swap over and test since that part of the light, i.e the ground flat insulated solder blobs and the alignment of the emitters is quite a pain to get right. I think I’ll live with the problem for now.

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Edit: And here is the test setup. Got this going pretty well at this stage, I can just snap a photo with my other phone every 30secs and get all the data bar the lux reading in one easy snapshot. :bigsmile:

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