# "Dark Star" quad SST-90 Elephant II @ 9000 lumens -video added-



## overdog (Mar 27, 2010)

Hello,
tonight I had to put some parts together:
-Fivemega´s Elephant II
-Fivemega´s 3X Turbo Head
-Custom made heatsink
-Ledil Lily-S reflectors from PhotonFanatic
-4x SSR-90-W65S-R11-GN-100 
-4x AW IMR 18650 cells

All the parts ready to go:








The SSR´s on the heatsink, wired in series:







Everything in it´s place:







Here it is:







Current measured at the tailcap, once I got over 10Ah, but got no pic:







"Dark Star" quad SST-90 Elephant II @ 9000 lumens, beamshot at white wall:







Beamshot DX SSC P7:






Quad SST-90:







Frankfurt Ho**day Inn:






"Dark Star" Ellie II quad SST-90 @ 9000 lumens:






*--- More beamshots in post #51 ---*
*--- Videolink in post #73* ---

...thank you for watching,
best regards from Frankfurt,
Steffen.


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## Dioni (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Wow... 9000lm  I hope the night come soon.


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## Yavox (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

What is the cost of all parts you have used to build the light, in total?


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## Eric242 (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Pay attention, you could sizzle your retina while taking those beam shots 

Eric


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## csa (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Wow... that's a LOT of light! I'm jealous...


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## Dioni (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



Yavox said:


> What is the cost of all parts you have used to build the light, in total?


 
+1
I think the OP could make a "cake recipe" for us [all jealous]!


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## led-it-be (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Wow! 9000 lumen AND you were able to convince your Gf/wife to help holding the multimeter probes?


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## tino_ale (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



led-it-be said:


> AND you were able to convince your Gf/wife to help holding the multimeter probes?


Good one 
Very nice setup :twothumbs


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## spencer (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



led-it-be said:


> Wow! 9000 lumen AND you were able to convince your Gf/wife to help holding the multimeter probes?


Good spot.

This is insane.


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## pepko (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

nice work ...


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## aurum (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

lol .... Runtime until it ? 2 or 3 minutes? :green:

cheers


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## PolarBearX (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

I was just drooling over the beamshots from the Black Star, and now this...  ..subscribed for the darkness

PBX


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## toby_pra (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Awesome mod again! :thumbsup:


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## rayman (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Great mode :twothumbs.

How does the switch handle the the current?

rayman


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## Dioni (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



led-it-be said:


> Wow! 9000 lumen AND you were able to convince your Gf/wife to help holding the multimeter probes?


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## TorchBoy (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Is that 10Ah for the battery with the cells in parallel? But you say the LEDs are in series, direct drive. Wouldn't the battery capacity be about a quarter of that, then?


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## jeffosborne (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Very sweet light, overdog! We did not see any driver - is this (gasp...) direct drive? Good work! Jeff O.


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## overdog (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Thank you for nice words!
@ Torchboy and Jeff: this light is direct driven- batteries and emitters in series.
@rayman: switch is little bit modified- too thin electrical leading contacts inside are thikened with solder- sorry, cannot better explain this...

best regards,
Steffen


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## don.gwapo (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Man, that thing is so bright. . You made us all jealous. :thumbsup:. I wouldn't call it dark star instead i call it shining star.


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## okarina (Mar 27, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

It's nice to see that someone do it and builds a really monster LED light 

What kind of betteries do you use?

I would liked to ask you at the Black Star's thread, but I ask you now: so, why don't you use some bigger, deeper and smoother reflectors? A lot of light just go out at the sides, so it's a big waste of power and light...

What's the temperature of this thing? After 5-10 minutes? Anyway, can it go for 5 mins?


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## moviles (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



TorchBoy said:


> Is that 10Ah for the battery with the cells in parallel? But you say the LEDs are in series, direct drive. Wouldn't the battery capacity be about a quarter of that, then?




what? sorry I cant understand what you say

I think the current draw its 10 amp

the leds and batteries are in series 

the capacity of the battery its 1.6 a/h 

18.8v x1.6a/h 23.68 w/h


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## moviles (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

nice mod :twothumbs

where you buy the ssr-90? MR muller?

what tint bin?


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## toby_pra (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

WUHUUUUUU

nice bamshots. Thats a white wall holymoly! :twothumbs


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## lucca brassi (Mar 28, 2010)

*SST-90 glue it or screw it ?*

I have a little insecurity with star SST-90 mouting.

I made some adjustable cooper heatsinks for my lights and I have noticed that SST-90 have not very clear grooves for screwing. 
I think now what it is better to glue it with thermal compound glue (AS) or fix it with screws and grease it with arctic silver ?

I see you choose glue ..... good decision ?


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## PolarBearX (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

looks like that used to be a pretty dark area of the city at night, I think I can see the Main in the second night shot :candle: 

How do you like this torch compared to others? Does it have noticeably more WOW factor?

PBX


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## Apollo Cree (Mar 28, 2010)

*Re: SST-90 glue it or screw it ?*



lucca brassi said:


> I have a little insecurity with star SST-90 mouting.
> 
> I made some adjustable cooper heatsinks for my lights.



The heatsinks are made from wooden barrels?


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## Dioni (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

 Thanks for the amazing beamshot!


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## TorchBoy (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



moviles said:


> the capacity of the battery its 1.6 a/h
> 
> 18.8v x1.6a/h 23.68 w/h


And now you're not making sense. Capacity is measured in amp-hours, not amps per hour. Energy is watt-hours, not watts per hour.


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## MrGman (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Based on what was given. 18.8V times 1.6 ampere hour rated battery should be 30 watt hour capability. If its really drawing close to 10 amps thats over 6 Couloumb draw from the batteries, not good. That would also be at 18.V (must assume some sag, probably more sag than that) X 10 amp draw, close to 180watts of real power consumption. 30 watt hour rating at best divided by 180 watt draw is actually 10 minutes of theoretical run time. Lets say 18V times 9 amps average 162 watts, brings you up over 11 minutes but still, I say that's a good way to have the batteries explode, be careful. Its better that its not a good constant current driver as that would be more likely to reverse charge a battery and have a  if the runtime was too long and the batteries not well balanced to each other. 

Another ouchmaker.


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## cmacclel (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



MrGman said:


> Based on what was given. 18.8V times 1.6 ampere hour rated battery should be 30 watt hour capability. If its really drawing close to 10 amps thats over 6 Couloumb draw from the batteries, not good. That would also be at 18.V (must assume some sag, probably more sag than that) X 10 amp draw, close to 180watts of real power consumption. 30 watt hour rating at best divided by 180 watt draw is actually 10 minutes of theoretical run time. Lets say 18V times 9 amps average 162 watts, brings you up over 11 minutes but still, I say that's a good way to have the batteries explode, be careful. Its better that its not a good constant current driver as that would be more likely to reverse charge a battery and have a  if the runtime was too long and the batteries not well balanced to each other.
> 
> Another ouchmaker.


 

I thought the IMR cells where good for 10c discharge. So that means the 1600mah 18650 would be good for 16 amps.

Mac


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## milkyspit (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



cmacclel said:


> I thought the IMR cells where good for 10c discharge. So that means the 1600mah 18650 would be good for 16 amps.
> 
> Mac




My recollection is 8C for the IMR cells, whereas more typical Li-ion chemistry should never be run beyond 2C. So 1600mAh capacity suggests max safe discharge rate of 12.8A. If the OP is reporting roughly 10A current draw, it's quite a bit but should still be within spec for the IMR cells.


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## MrGman (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

I didn't see that he mentioned they were IMR batteries, I am guessing you recognize them from the picture and the reduced current capacity. All well and good then. If someone were to do this with non IMR cells that would be far more dangerous. He should state that with big letters he is using IMR style batteries only to help keep the risk of explosive level venting down to a far more reasonable minimum.


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## milkyspit (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



MrGman said:


> I didn't see that he mentioned they were IMR batteries, I am guessing you recognize them from the picture and the reduced current capacity. All well and good then. If someone were to do this with non IMR cells that would be far more dangerous. He should state that with big letters he is using IMR style batteries only to help keep the risk of explosive level venting down to a far more reasonable minimum.



Yup. Look at the second cell from the right... the letters "IMR" are clearly visible, and the cell itself is in the characteristic red jacket of the AW branded IMR cells.

*You're absolutely right... regular lithium-ion cells would be a VERY BAD IDEA in this application. The protection circuit on the AW protected 18650 would theoretically disconnect the circuit before bad things could happen, but that's mostly a failsafe, not something to rely on as a primary line of defense. Even worse would be unprotected lithium-ion cells, which would run happily until they... well, pretty much exploded in a big cloud of flames and noxious fumes. (I've boldfaced this paragraph to highlight its importance to safety.)*

Going the other direction, best cell chemistry of all might be A123Systems cells, though the voltage is a bit different so one would need to play with the setup a bit to get the right match between cells and LEDs. A123Systems cells are fully capable of delivering far more current than this application requires, and have demonstrated themselves to be non-volatile (no flames, no big boom) even when badly abused... at least last time I'd spent the time to research them.

SilverFox would be a great resource on these cells. Perhaps he might drop by at some point?


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## NightTime (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

More beamshots please !



Just amazing !


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## richardcpf (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Runtime?

:naughty:


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## flashfiend (Mar 28, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Is the concern about batteries mostly for a series setup? I have a parallel wired dual bore powering 1 sst-90 using 2 AW Protected 18650s and it ran fine. I got into trouble when I ran it with 2 IMR 18650s (Led got fried).


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## moviles (Mar 29, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



MrGman said:


> I didn't see that he mentioned they were IMR batteries, I am guessing you recognize them from the picture and the reduced current capacity. All well and good then. If someone were to do this with non IMR cells that would be far more dangerous. He should state that with big letters he is using IMR style batteries only to help keep the risk of explosive level venting down to a far more reasonable minimum.



yea it use aw18650 imr 1600 mah batteries with safe chemistry (16 amp max ) :thumbsup: 


*IMR18650 Specifications :
*
Nominal Voltage : 3.7V
Capacity : 1600mAH 
Lowest Discharge Voltage : 2.50V
Standard Charge : CC/CV ( max. charging rate 4.5A )
Cycle Life : > 500 cycles
*Max. continuous discharge rate : 10C*








its true.maybe He should state that with big letters he is using safe IMR batteries


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## overdog (Mar 29, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

...unfortunately I did not win in the lottery at the weekend to get my budget back in balance , but thank you all for nice comments- this is much more worth to me:twothumbs!
@moviles: good idea- I changed post one and specified which kind of batteries I use for this setup... your question. for exact binning I have to look at home- still at work..
@okarina: I tried to keep this mod as simple as possible for me - the Ledil Lily-S are the first reflectors I know that are especially made for the SST-90 and they are really short- using any deeper and modified reflector would also have meant to me to change the design of the heatsink, to make it smaller in depth or to complicate its building in any way- so I have chosen the Lily-S´s for fist try and I am really confident with their performance- may I will try some optics from PhotonFanatic in the next step... total runtime of this light should be less than 10 minutes, I ran it for 4-5 minutes nonstop at the weekend and nothing exploded, melted and no airplane landed besides of me...
@lucca brassi: the stars are glued with arctic silver, they are also kept in place by the lens, when bezel is completely screwed down.
@flashfiend: in my opinion 2 parallel IMR 18650 cells cannot fry your SST-90, I would say that your emitter may was not connected proper enough to the heatsink?

I will find a good place outside for some more beamshots later this week and post them.

Best regards,
Steffen.


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## okarina (Mar 29, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



overdog said:


> no airplane landed besides of me...



:twothumbs

It would be the smallest problem... I fear that one day NASA will get your *** f*cked, because you blinded the crew on ISS


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## flashfiend (Mar 29, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Sorry Steffen, I'm not trying to hijack your thread but this is a picture of my LED that got fried. I thought the LED was mounted to the heatsink properly. What do you think?


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## okarina (Mar 29, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



flashfiend said:


> Sorry Steffen, I'm not trying to hijack your thread but this is a picture of my LED that got fried. I thought the LED was mounted to the heatsink properly. What do you think?



I think the major problem is that you bought the LED alone. Why don't you bought it on a star?  Or why don't you soldered it on a star? Just soldering two wires on it and just put it on the thermal compound is the worst you can do, especially with such a special LED...

Too much thermal compound will thermaly isolate the LED.

Buy another one on a Star :thumbsup:


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## darkzero (Mar 29, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



okarina said:


> I think the major problem is that you bought the LED alone.


 
I disagree. The issue that I see is way too much thermal epoxy that was used. Using a very thin layer of thermal epoxy to mount the emitter to that heatsink it should perform just fine.


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## okarina (Mar 29, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

QUOTE


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## gringo1 (Mar 30, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

nice work steffen:twothumbs


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## David Gretzmier (Mar 31, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

wow. 9000 lumens. from basically putting parts together that anyone here can buy for around 600 bucks, except for the flying saucer heatsink. so about 15 lumens per dollar. if you are pulling 10 amps from each cell, they are 1.6 amp hour rated, then 1.6/10 hours or 15 minutes or so. 

I think I like the 3 x sr-90 earlier from basically the same parts, with the d2flex that lets you dim and use everyday.


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## calebra (Apr 1, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

hmm, i understood an sst-90 could take a maximum of 13.5 amps, and it could take more but no extra light would be given off over that, just extra heat. i wonder if one of the electrical boffs could chime in here, as to me some figures arnt adding up, nice build anyway.


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## overdog (Apr 1, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

@flashfiend: not easy to judge from a pic, but from what I can see and my little experience (same configuration- same problem- no proper contact because of too much thermal epoxy...) I agree to darkzero.

@David: I am thinking about putting in a D2Flex- but I am not really shure if the board will survive in this constellation- in my Mag 1D at 9Ah it worked without problems- but in this light it has to handle the 9Ah + voltage x4!--- But I will not find out without trying.. (before this I´ll take some more beamshots...)

@calebra: sorry, but my english does not last for understanding the meaning of your words...If there is a question in it, please let me know in other words.. 

best regards,
Steffen


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## flashfiend (Apr 1, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Darkzero & overdog. Thank-you for your input. I will consider the thermal compound issue but honestly this was a light built for me not by me. I don't have tools to build myself. Overdog, as for your setup I thought yours have been using nimhs and a single led not parallel Li-ions. Darkzero I may pm you with further questions.


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## overdog (Apr 1, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Hello flashfiend, (from what I learned here two IMR cells in parallel are able to deliver more energy to the emitter than two Li-Ion cells cause of their chemistry- may your heatsinking worked well with two Li-Ions, but with two IMR-cells the emitter decided to get more input to produce more power what caused increasing heat- enough heat to bring your emitter to the limits with bad heatsinking, caused by too much thermal epoxy...

?


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## flashfiend (Apr 1, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



overdog said:


> Hello flashfiend, (from what I learned here two IMR cells in parallel are able to deliver more energy to the emitter than two Li-Ion cells cause of their chemistry- may your heatsinking worked well with two Li-Ions, but with two IMR-cells the emitter decided to get more input to produce more power what caused increasing heat- enough heat to bring your emitter to the limits with bad heatsinking, caused by too much thermal epoxy...
> 
> ?



Yes, my builder suggested the same thing but I am still running into problems with 2 protected AW 18650's. I am going to try and find out if anyone else with the exact same setup as mine is running into the same or similar problems. I have built PC's before and I know excessive thermal compound is not a good thing. At this point I am just trying to get my light to run with no issues. Btw, a 4xAA Nimh setup by the same builder has no issues and is amazing. Hopefully parallel Li-Ions is not the reason for my problems.

Sorry overdog if this is hijacking your thread. 

To get back on topic...

The lights you have built overdog, have been nothing short of amazing and the Dark Star is no exception. I can't wait to see more of your creations.


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## overdog (Apr 4, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*

Hello,


this evening as soon as it was not raining cats and dogs I took the chance to get some more beamshots- although I fixed my new M8910 handycam, I only got blurred pictures- but I hope there
is still enough to see...


Frankfurt Ho**day Inn:







beamshot with XPG-R5:







quad SST-90:







little higher:







quad SST-90:







Thank you for watching & happy easter,
Steffen.


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## Dioni (Apr 4, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

Wow.. 
Its insane! Thanks and happy easter too!


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## David Gretzmier (Apr 5, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

normally to uplight a 24 story building, we would use 4 1000 watt metal halides at the corners. or you could just use a flashlight. that thing is scary bright.


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## guiri (Apr 5, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

Sweet! 

So, our German friend. Will you make and sell something like this?

George


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## don.gwapo (Apr 5, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

Whoa. . Imagine a single flashlight that almost light up an entire building. I'm sure those people inside that building are surprised/puzzled when you light it up. . Looks like spotlights will become obsolete soon replace by led flashlights. :naughty:. Thanks for sharing.


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## ti-force (Apr 5, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



flashfiend said:


> Yes, my builder suggested the same thing but I am still running into problems with 2 protected AW 18650's. I am going to try and find out if anyone else with the exact same setup as mine is running into the same or similar problems. I have built PC's before and I know excessive thermal compound is not a good thing. At this point I am just trying to get my light to run with no issues. Btw, a 4xAA Nimh setup by the same builder has no issues and is amazing. Hopefully parallel Li-Ions is not the reason for my problems.
> 
> Sorry overdog if this is hijacking your thread.
> 
> ...


 

If I were you, I'd start a new thread about this problem. There are plenty of knowledgeable people on here, and I'm sure someone will help you figure out your problem. Of course, you will need to have, or have access to the tools needed to diagnose your problem in the manner that's suggested. To me, it sounds like you need a driver or added resistance of some type; I think you're experiencing thermal runaway. As the emitter heats up, the emitters vf drops and the current goes up and up and up until .


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## Justin Case (Apr 5, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



MrGman said:


> Based on what was given. 18.8V times 1.6 ampere hour rated battery should be 30 watt hour capability. If its really drawing close to 10 amps thats over 6 Couloumb draw from the batteries, not good.


 
When a cell is rated for some discharge rate of 2C or 10C or whatever, the "C" is not Coulombs of charge. The "C" refers to the cell's capacity in mAh.

Six Coulombs is the amount of charge passed in six seconds by a 1A current. That doesn't make a lot of sense in the context of this Dark Star thread.

AW's IMR18650 cells are rated at 10C, which means that those cells are rated up to 16A discharge.


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## Justin Case (Apr 5, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



okarina said:


> I think the major problem is that you bought the LED alone. Why don't you bought it on a star?  Or why don't you soldered it on a star? Just soldering two wires on it and just put it on the thermal compound is the worst you can do, especially with such a special LED...
> 
> Too much thermal compound will thermaly isolate the LED.
> 
> Buy another one on a Star :thumbsup:


 
This is not correct. If you used a star, you'd still have to use some sort of thermal compound or thermal adhesive under the star. But now you've also added the thermal resistance of the star to the system.

The SST-90 datasheet states that the thermal resistance from junction to case is 0.64 C/W. That's the best you are going to get. When you add a star, the thermal resistance from junction to MCPCB is now 2.02 C/W. You've increased the thermal resistance by 3X by adding a star.

The added thermal resistance from the thermal compound or adhesive is given by

bond line thickness/(thermal conductivity of the thermal material you are using * effective contact area)

Thus, you want to have a thin layer of thermal compound or thermal adhesive between the SST-90 and the heat sink. You also want to make sure that there are no bubbles between the SST-90's thermal contact and the thermal compound or adhesive. Finally, you want to use a material with thermal conductivity consistent with what you need to keep your LED cool.

Let's assume that you choose Arctic Alumina or similar thermal epoxy. The thermal conductivity of alumina-filled epoxies is about 2.5 W/m-K.

The SST-90 thermal contact area is 9mm x5.1mm = 4.59x10^-5 m^2.

Let's consider two different bond line thicknesses -- 0.001" and 0.005".

For the thinner bond line, I calculate a thermal resistance of 0.22 C/W. For the thicker bond line, the thermal resistance is 5X greater, or 1.1 C/W.

Thus, the total thermal resistance is 0.22+0.64=0.86 C/W or 1.1+0.64=1.74 C/W. Basically, a 2X difference total.

If you run your SST-90 at full power (9A at about 3.6V, or 32W), the SST-90 junction temperature can be 0.86*32=28C to 1.74*32=56C hotter than your heat sink. Strictly speaking, perhaps I should multiply the 32W by the inefficiency of LEDs in converting electricial power to light (i.e., about 80% of the power goes to waste heat), but you get the idea.

Pretty clearly, it is advisable IMO to use a bare emitter if possible, not a star, and to use as thin of a bond line as possible. I'd probably also use Arctic Silver adhesive, which has about 3X better thermal conductivity than Arctic Alumina adhesive. Or use Arctic Silver 5 compound, with even better thermal conductivity, and then use regular epoxy around the perimeter of the SST-90 to glue it in place. Using Arctic Silver gives you some leeway in case your bond line is not as thin as it ought to be.

A single IMR18650 can definitely hold above 3.6V at 10A draw for at least a minute. 2P should last longer. Is this long enough to fry an SST-90? Perhaps, especially if the LED is poorly heat sinked.


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## Justin Case (Apr 5, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



flashfiend said:


> Yes, my builder suggested the same thing but I am still running into problems with 2 protected AW 18650's. I am going to try and find out if anyone else with the exact same setup as mine is running into the same or similar problems. I have built PC's before and I know excessive thermal compound is not a good thing. At this point I am just trying to get my light to run with no issues. Btw, a 4xAA Nimh setup by the same builder has no issues and is amazing. Hopefully parallel Li-Ions is not the reason for my problems.


 
Measure the current draw for a single cell, 2P IMRs, and 2P ICRs.


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## ti-force (Apr 5, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



Justin Case said:


> Or use Arctic Silver 5 compound, with even better thermal conductivity, and then use regular epoxy around the perimeter of the SST-90 to glue it in place. Using Arctic Silver gives you some leeway in case your bond line is not as thin as it ought to be.


 

That's an excellent idea! What do you consider "regular epoxy" for applying around the perimeter? Just an epoxy that's meant for bonding the types of materials involved?

Thanks


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## Justin Case (Apr 5, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

That's right. Just some plain 2-part epoxy that you'd use as a general glue. Devcon, Loctite, whatever. You could use thermal epoxy, but since it wouldn't be in contact with any decent thermal path (the PCB is probably a poor conductor), thermal epoxy wouldn't do anything to improve thermal management.

If Arctic Silver 5 is too expensive, you could go for Arctic Alumina compound, which would still give you close to 2X thermal conductivity improvement over AA epoxy.


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## ti-force (Apr 5, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*



Justin Case said:


> That's right. Just some plain 2-part epoxy that you'd use as a general glue. Devcon, Loctite, whatever. You could use thermal epoxy, but since it wouldn't be in contact with any decent thermal path (the PCB is probably a poor conductor), thermal epoxy wouldn't do anything to improve thermal management.
> 
> If Arctic Silver 5 is too expensive, you could go for Arctic Alumina compound, which would still give you close to 2X thermal conductivity improvement over AA epoxy.


 

Thank you:thumbsup:


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## ramrod1708 (Apr 5, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

Hi Steffen. 
Are you from Frankfurt am Main? 

Best regards,
Patrick


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## flashfiend (Apr 6, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens*



Justin Case said:


> Measure the current draw for a single cell, 2P IMRs, and 2P ICRs.



I have a DMM but I was unsure of how to do this in my Mag setup with D2flex (I knew how to do it in my 6P clone builds and attempts using a similar method proved unreliable. Could be due to my cheap DMM). I actually had issues just with a single IMR. Two has already killed one LED. Anyways, the light has gone back to the builder for evaluation. Thanks for all the help. If you or anyone else has anymore tips, please PM me as I've taken away enough attention from Steffen's fantastic build.


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## overdog (Apr 9, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

@ Dioni, David, George, don.gwapo: Thank you- I think I have to find some more interesting objects to get beamshots- I for myself am still impressed by the output of this light- Maybee this weekend I will put in D2Flex to make this light more usable to get different modes- But I am still not sure if this light will bring the driver to the limits... (anybody has an idea/ similar experiences?)
...I got some requests per PM if I will sell this light- thanks for, but at this time I am not going to sell it..
@ Patrick: close to Frankfurt.... 

Have a nice weekend,
Steffen


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## guiri (Apr 9, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

Hell, last time I was in Frankfurt was in 76 and I was at the airport. All I remember is that damn terminal seemed to be ten miles long and I had to walk from one end to the other 

George


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## overdog (Apr 12, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

Hi George,
...in the 90´s they finished a second terminal and meanwhile the whole airport seems to me to be much bigger than the little 10000 souls city close to FfM I live in- may I should take some beamshots at the airport- but I am sure they would arrest me for that... ...


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## guiri (Apr 12, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

They might arrest you and make you WALK THE DAMN THING! 

I remember the damn thing was huge and that's ALL I remember


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## rizky_p (Apr 13, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

Oh man that is awesome. I wish i could afford the host itself..lovecpf there goes my saving


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## Kestrel (Apr 13, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

Great beamshots illuminating the side of the building like that. Sweet light. :huh:



MrGman said:


> If its really drawing close to 10 amps thats over 6 Couloumb draw from the batteries, not good. That would also be at 18.V (must assume some sag, probably more sag than that) X 10 amp draw, close to 180watts of real power consumption. 30 watt hour rating at best divided by 180 watt draw is actually 10 minutes of theoretical run time. Lets say 18V times 9 amps average 162 watts, brings you up over 11 minutes but still, I say that's a good way to have the batteries explode, be careful.





cmacclel said:


> I thought the IMR cells where good for 10c discharge. So that means the 1600mah 18650 would be good for 16 amps.





milkyspit said:


> My recollection is 8C for the IMR cells, whereas more typical Li-ion chemistry should never be run beyond 2C. So 1600mAh capacity suggests max safe discharge rate of 12.8A. If the OP is reporting roughly 10A current draw, it's quite a bit but should still be within spec for the IMR cells.





Justin Case said:


> When a cell is rated for some discharge rate of 2C or 10C or whatever, the "C" is not Coulombs of charge. The "C" refers to the cell's capacity in mAh. Six Coulombs is the amount of charge passed in six seconds by a 1A current. That doesn't make a lot of sense in the context of this Dark Star thread. AW's IMR18650 cells are rated at 10C, which means that those cells are rated up to 16A discharge.


 
Good posts. I think that one lesson here might be, better to remain silent and be thought a fool than to open one's mouth and remove all doubt. 



MrGman said:


> I didn't see that he mentioned they were IMR batteries, I am guessing you recognize them from the picture and the reduced current capacity. All well and good then.


I'm sure the OP is quite relieved to find that his expertise in custom builds meets your high standards of technical accuracy. 

BTW since you mentioned it though, IMR cells have *increased* current capacity but *reduced* overall energy capacity - probably just a typo in your post though. I'm surprised you didn't recognize the (very distinctive) AW IMR cells in the OP's picture, do you have any of them?


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## MrGman (Apr 13, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*



Kestrel said:


> Great beamshots illuminating the side of the building like that. Sweet light. :huh:
> 
> 
> 
> ...


 

Kind a late to the party on that discussion aren't you? 

Just for the record I still cannot read that it says IMR on the cells in the original photo at the start of this thread on the lap top monitor I am using and my eyeglass prescription. Forgive me for not having enough visual quality on the monitor or acuity. My eyes are not what they used to be. Maybe someday yours won't be either. Yes I am aware the IMR cells have less energy capacity even though they are rated to deliver higher rates of current. I didn't bother to go back and correct my post, no longer interested. Even though the IMR cells are far safer to deliver the current I still don't like the design in general of such a high current draw device with 4 cells in series or 6 or 8 or whatever. In light of other recent flashlights that have exploded when I first saw this and did not recognize the cells as IMR I thought the warning was appropriate. 

Some one else may see this and try to duplicate it and not use IMR cells for some strange reason and may have a big poof in their face. They might think that if they only turn it on for 30 seconds it won't hurt. That's where I am coming from. Don't mine being the safety fool at all.

I only apologize if I stated it in an incorrect manner that could not be understood.


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## wheelema (Apr 13, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*



Justin Case said:


> That's right. Just some plain 2-part epoxy that you'd use as a general glue. Devcon, Loctite, whatever. You could use thermal epoxy, but since it wouldn't be in contact with any decent thermal path (the PCB is probably a poor conductor), thermal epoxy wouldn't do anything to improve thermal management.
> 
> If Arctic Silver 5 is too expensive, you could go for Arctic Alumina compound, which would still give you close to 2X thermal conductivity improvement over AA epoxy.


Justin,

Do you have any opinion re: 3M thermal tape instead of Arctic Silver? My perception is that you pay more in exchange for a consistent bond. Do you have any insights?


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## overdog (Apr 16, 2010)

*Re: "Dark Star" quad SST-90 Elephant II @ 9000 lumens -beamshots added-*

Hello,
I posted a short video with beamshots, you can watch it 
HERE
- don´t wonder, why I "dance" around the flashlight- I do not wait for rain, I just wanted to make sure this way to some critical viewers that there is no additional light behind my handycamera- Some said that about my first video with the triple SST-90... Have fun...


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## guiri (Apr 17, 2010)

I personally like your little dance there brother. Should have worn the lederhosen though and of course, you should have had some accordion music in the background 

George


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## overdog (Apr 19, 2010)

Hello George,
...like this?


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## guiri (Apr 19, 2010)

Absolutely 

I had a pair when I was a kid and I loved them. Of course, I outgrew them but hey, those are some long lasting things


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## guiri (Apr 19, 2010)

Damn! That is soo wrong on so many levels... 

Anyway, as I was saying....


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## Mettee (Apr 19, 2010)

dude I just looked at this thread and now I am real scared.


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## guiri (Apr 19, 2010)

What? The light scared you? 

Surely it wasn't the long legged chick that did it was it? If so, I sincerely apologize.....


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## was.lost.but.now.found (Apr 19, 2010)

guiri said:


> What? The light scared you?
> 
> Surely it wasn't the long legged chick that did it was it? If so, I sincerely apologize.....


 
Juts tell us which one of those is you and you'll be forgiven.


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## guiri (Apr 19, 2010)

Actually, I AM the long legged chick...


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## Kestrel (Apr 19, 2010)

C'mon, folks, ~9 more posts and we can get this thread to page 4 - safely cycling off the disturbing pics to the previous page. :green:


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## Mettee (Apr 19, 2010)

Kestrel said:


> C'mon, folks, ~9 more posts and we can get this thread to page 4 - safely cycling off the disturbing pics to the previous page. :green:




Yes please! Ha


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## David Gretzmier (Apr 20, 2010)

also watched the video of the 3x sr-90, with d2flex. sweet dimming.


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## was.lost.but.now.found (Apr 20, 2010)

Kestrel said:


> C'mon, folks, ~9 more posts and we can get this thread to page 4 - safely cycling off the disturbing pics to the previous page. :green:


 
I'm on a 50 post/page view, so as of this post I still need 15 more.:mecry:


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## overdog (Apr 24, 2010)

...was a week not on forum... - you are all completely crazy 
@ David Gretzmier: ...thank you...
@ all: shall I put in D2Flex or not? - will the driver stand the conditions or not? anybody has any experience with?

Best regards from Lederhosentown,
Steffen.


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## guiri (Apr 24, 2010)

Welcome back boss 

Alright, if someone is getting physically sick, I can remove the pics :devil:


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## overdog (May 1, 2010)

Hello George,
I cannot forget the pics, so I´ll have to do this ...
:whoopin:


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## guiri (May 1, 2010)

That's right, I'll take the blame!


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## cherrymonkey (Mar 29, 2011)

Great beam! What was the total cost for all the parts?


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## Volvo (Jul 24, 2011)

Holy crap.

9000lumens. :naughty:
That´s what i called a nice flashlight.


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