# My 1st 2D Mag SST-90/SSR-90 build...I have ??'s



## bigchelis (May 28, 2010)

Hi folks,

I am getting help from a buddy to build me non-pedestal heatsinks. It looks all that is available is raised on a pedestal. I will make 3 heatsinks; copper, aluminum, and brass. I will run the SST-90 direct drive with stock 2D Mag Switch. Powered by 3 NiMH Tenergy C cells or 4 SubC NiMH cells. Then I can see which heatsink material works best. Oh, and 24gauge wire will be used. 


I wanted to purchase one of the SST-90 sold at 4sevens, but it doesn't have a star. If I will only use this direct drive; do I still need the SSR-90???

My goal is to get 1800 OTF lumens and still have 1500 OTF at 3~5 minutes So, far not even the mighty SSR90 from Olight can do this.

Thanks,
bigC


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## Hill (May 28, 2010)

Hi Big C,

Some quick thoughts on your idea (I'm sure TJ will chime in since he has had vast more experience)

Use 20 - 21g wire (24g is only rated to 3.5A according to this chart)

SST-50 wo/ star is ok, but make sure it's firmly attached to the sink. As I'm sure you know, heatsinking is critical as this sucker produces massive amounts of heat.

Isn't the stock mag switch 5A max?? You may want to check on that.

Not sure about those battery combos. I know others have gone dd with NiMh. I want to say you may need to have 4 x SubC to get max output.

Good luck!


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## bigchelis (May 28, 2010)

Hill said:


> Hi Big C,
> 
> Some quick thoughts on your idea (I'm sure TJ will chime in since he has had vast more experience)
> 
> ...


 

I will go for the 20~21g wire then. 

The stock Mag D size switch I been reading is good up to 10A.


I figured that I will need 4 NiMH C cells to run the LED at full 9~10A since 3 of them might give me just 3~5A:thinking:

Now I still not sure if I can purchase the sST-90 without the Star or not:candle::candle:


EDIT: I am going with an SSR-90 from Photon Fanatic and at $60 dollars those 65k color ones are not cheap.

I am doing a heatsink similar to this one from Lambdalights.com, but I plan on putting a lip on mine and making it 1.5in~1.8in in total lengh.









Thanks,
bigC


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## ti-force (May 29, 2010)

This will definitely be interesting :thumbsup:, but my money is on the aluminum, then again, I'm not a betting man and there's a reason for that.

How are you planning to attach the star to each heatsink? Will you drill and tap each heatsink so you can tighten the star down with screws? If so, I'm assuming you will apply AS5 under the star for each heatsink.

Also, I have very little experience with direct drive applications, but I do know that you can fry one of these emitters very quickly if you're not careful. I fried one pretty darn fast with a Li-ion, but I gained some knowledge from it; when the tint starts shifting to blue, see just how fast you can cut power, then let the emitter cool for a minute.

I don't really have much experience with NiMH cells either, but if they have a nominal voltage of 1.2v per cell, 4 cells would be 4.8v. The SST-90 datasheet says a typical vf of 3.87v at 9A and 3.9v max. I would also keep in mind the "burn-in" that Techjunkie discovered which lowers the vf of the emitter. Click here for the thread. If you lower the vf, the current will likely go up. Like I said though, my experience with direct drive applications is limited, so I'm just thinking out loud here.


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## Hill (May 29, 2010)

bigchelis said:


> I will go for the 20~21g wire then.
> 
> The stock Mag D size switch I been reading is good up to 10A.
> 
> ...



Hey bigC,

That's a sweet heatsink!! You do that yourself? All my custom sinks are painstakingly had cut and glued. They work, but are a difficult to make and never look pretty.

I'm betting on the copper sink to be the best.


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## FroggyTaco (May 30, 2010)

Using my knowledge from PC CPU cooling, the aluminum will be worse than the copper. The CPU cooler people never use brass so either it's too expensive or isn't a good enough conductor to compete with brass.

The evolution of PC CPU cooling stared out with aluminum, then the better companies started using copper baseplates that transitioned to aluminum fins/pins, then all copper, then heat pipes came on the scene. 

When absolute max performance is required, all copper is employed regardless of the cooling technique. So my vote goes for the copper. Make sure you use your AS5 when install that slug in the tube.

Travis


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## vestureofblood (May 30, 2010)

Hi Bigchelis,

Cool project. I will be interested to see how this works out. 

In my xp 20 awg wire has perfect for this type light. I use Accupower C cells in mine and on only 3 cells DD current draw was about 11-12 amp. Depending on what you use to measure the current you may need the extra cell during your test. I made a set of leads for my DMM using some thick copper wire ( 12 AWG ish maybe) to more accurately simulate the output with the tailcap on.

Good luck and thanks for sharing


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## bstrickler (May 30, 2010)

If you're going to use 20g wire, I would get some silicon wire from here:


http://www.radicalrc.com/shop/?shop=1&cat=64 $3 for 1 meter of red & 1 meter of black

You could always get 4 sub-c cells, then drive it with 3 sub-c's first, and check what the voltage drop is, and how much current you're putting to the LED. A 4th cell may make the LED go , which I don't think you want!

~Brian


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## HarryN (May 30, 2010)

Thanks for the link to the wire.


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## ti-force (May 30, 2010)

FroggyTaco said:


> When absolute max performance is required, all copper is employed regardless of the cooling technique.
> 
> Travis



I know very little about thermal transfer rates with different materials, but I do know that copper tramples aluminum in thermal transfer. I just wonder if the heatsink will get saturated, or too hot, too quickly, but maybe the copper will transfer the heat to the aluminum body quickly enough that it will keep the heat moving. My choice of the aluminum heatsink winning in this showdown was really just an uneducated guess , and I thought I'd root for the underdog.


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## FroggyTaco (May 30, 2010)

ti-force said:


> I know very little about thermal transfer rates with different materials, but I do know that copper tramples aluminum in thermal transfer. I just wonder if the heatsink will get saturated, or too hot, too quickly, but maybe the copper will transfer the heat to the aluminum body quickly enough that it will keep the heat moving. My choice of the aluminum heatsink winning in this showdown was really just an uneducated guess , and I thought I'd root for the underdog.



You hit upon the the crux of the issue. Can the entire heatsink system ie: the emitter heatsink & the flashlight body cope with the heat dump of the emitter.

The copper is better not only in heat transfer, but also heat absorption capacity. Think of it as a bigger sponge if relating to absorbing water.

Travis

p.s. I like rooting for the underdog, but since there is no heart in the matter were screwed! :buddies: :lolsign:


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## Al Combs (May 30, 2010)

Three heatsinks from different metals. This should be interesting. I'll be curious to see the results of that comparison. Do you have a DMM with a thermistor probe? I have a really cheap DMM. When I put together my SST-90, I thought about buying a small SMT thermistor. I was going to make a chart of the resistance vs temperature for say every 5°C from the mfgr. data. I had nothing to compare it to. I just wanted to see how long a Mag-D with an SST-90 can run before it gets too hot. I was in too much of a hurry to see a 2,000 lumen flashlight though.:devil:

I use the same table Hill pointed to for wiring. Maybe you can make some good use of wire that's "too" small. It would act like a built in resistor. The 4/5SubC Sanyo NiCad's I bought have a 5.5 milliohm internal resistance @ 50% charge according to Sanyo. They only drop about 1/8 volt under the 10.25 amp load my DIWdiver regulator puts on 4 of them. Under load they measured 4.96 volts. The Vf of my LED is 3.88 volts at the moment. Three of these high drain batteries would only be about 6 amps. And 4 of them would definitely blow the LED. I think if you get the highest capacity SubC you can find would be the best for a 4 battery direct drive setup. High drain and high capacity are to some extent, mutually exclusive. So high capacity cells and thin wire might work very well together. The bad thing about direct drive testing with a DMM on the amp scale is it will take more power when you remove the meter. Unless of course you are lucky enough to own a clamp meter. Keep an eye out for an "angry blue" LED.

I'm betting that a solid hunk of copper will not work as well as aluminum or brass. Brass and aluminum are about the same. Since brass is so much more expensive, the only reason to use it is if you want to solder to it. The specific heat (amount of heat required to raise the temp) of copper is much lower than aluminum. So copper gets hotter faster. Even though copper has more than double the thermal conductivity of aluminum. Specific heat as a measurement involves the weight of the material as well. Even after you factor in copper's higher density, aluminum still has a better specific heat characteristic than copper.

I wouldn't have picked copper (read stole the design:naughty for my heatsink core if I didn't think it had awesome thermal properties. As FroggyTaco said, modern day CPU coolers all use copper. I just think it depends as much on good design as on the properties of the metal.


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## aurum (May 30, 2010)

The best material for heasinking is silver (430 W/mK) ... coper is 401 W/mK, gold 314 W/mk (!) Al is 230 W/mk and brass is 120 W/mk .... coper is able to store lot more heat compared to Al. I always use coper for my SST/SSR builds  -> In Germany we call it Wiedemann-Franzschen Gesetz. It explains the reason for this behavior (siehe auch: Pauli Prinzip)


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## admacdo (May 30, 2010)

It always impresses me just how much knowledge one has to aquire when going into something like this which covers so many areas. As many people have found, it's not just a case of whacking it all together. Current carrying capacities, and accumulated resistance in the circuits all start to get individual attention. I'll be watching this thread to see how things develop. Good work all!


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## Justin Case (May 30, 2010)

Al Combs said:


> I'm betting that a solid hunk of copper will not work as well as aluminum or brass. Brass and aluminum are about the same. Since brass is so much more expensive, the only reason to use it is if you want to solder to it. The specific heat (amount of heat required to raise the temp) of copper is much lower than aluminum. So copper gets hotter faster. Even though copper has more than double the thermal conductivity of aluminum. Specific heat as a measurement involves the weight of the material as well. Even after you factor in copper's higher density, aluminum still has a better specific heat characteristic than copper.



Yes, the specific heat of Al is about 2X that of copper. But that isn't the relevant spec here. Since the heat sink is going into a fixed volume (a 2D Mag body/head), the relevant spec is probably thermal volume. Copper is superior to aluminum on a per volume basis by about 50%. Of course, one could always make the relevant spec to be specific heat by making the max acceptable mass your constant instead of volume. But then the heat sink using a more dense material would get shortchanged because it would be smaller in volume that the heat sink using a less dense material. There would be little point, IMO, to make a heat sink undersized for the available volume, especially when you are looking at something as high-powered as an SST-90/SSR-90.

BigC, if you can max out the power delivered to the SST-90/SSR-90, you will be looking at around 32W of power draw by the LED, or perhaps about 25W of waste heat generated that has to be dissipated by your heat sink and Mag host. That is a lot of heat. In some ways, it is fortunate that you aren't going to use a driver because between the driver's waste heat and the LED's waste heat, you'd have a real thermal management challenge to keep the system happy.


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## bigchelis (May 31, 2010)

The heatsink is actually something Lambdalights has been working on to help with his heat issues on the Vara2000 SST-90. He gave me his specs and pictures of his for me to attemp to duplicate it, since he already saw improvements with his heatsink.

The heatsinks will have holes big enough for 14g wires to fit and I think I should try both 14g and 20g just for kicks.

I will try SST-90 with 3 NiMH cells 1st and if I get sub 5A curret then I will try 4 NiMH cells. I hope I get full power with just 3 cells, but so far it looks like the 4 NiMH cells will win.


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## kito109654 (May 31, 2010)

Two words: liquid cooled. 


 Subscribed.


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## FroggyTaco (May 31, 2010)

kito109654 said:


> Two words: liquid cooled.
> 
> 
> Subscribed.



If we look to PC CPU cooling, the next evolution is heatpipes. No moving parts, no maintenance, & amazing ability to literally move heat to a different part of the host.

How that would work in a ergonomic flashlight is beyond my comprehension though.

Travis

p.s. I am on my 5th water cooled PC so I am all for it but.....


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## flashfiend (May 31, 2010)

FroggyTaco said:


> If we look to PC CPU cooling, the next evolution is heatpipes. No moving parts, no maintenance, & amazing ability to literally move heat to a different part of the host.
> 
> How that would work in a ergonomic flashlight is beyond my comprehension though.
> 
> ...



I'm thinking of a single unit head and heatsink/heatpipes w/reflector and glass held down by bezel. Of course extending to the PC world I'd like to see where the LED attaches via pins or a ball grid array and becomes upgradeable like a CPU.


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## Al Combs (May 31, 2010)

Justin Case said:


> Yes, the specific heat of Al is about 2X that of copper. But that isn't the relevant spec here. Since the heat sink is going into a fixed volume (a 2D Mag body/head), the relevant spec is probably thermal volume. Copper is superior to aluminum on a per volume basis by about 50%.


Pure copper has about 40% more volumetric heat capacity than pure aluminum. Funny all the sites I Googled for specific heat were a little different. Anyway I think the relevant spec is a type of aluminum someone would actually use in a flashlight. Here is a data chart showing T6061 aluminum vs C110 copper. Not the last word, but typical of what I saw. The adjusted volumetric specific heat put copper in the lead by only 1%. If you use draw copper then T6061 is the winner by slightly under 3%. Too close to call I'd say. My mistake guys, I thought aluminum was the clear winner.


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## Justin Case (Jun 1, 2010)

The problem is that the linked aluminum alloy data for specific heat capacity is questionable. It seems about 30%-50% higher than several other sources:

http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA6061t6
http://www.sas.org/engineerByMaterial.html
http://edboyden.org/constants.html


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## HarryN (Jun 1, 2010)

The real challenge will be how to move that heat out of the light body into the air. The body can move about 12 - 15 watts from the light using "liquid cooling". (blood flow). After that, it gets dicey.

I suggest holding / drinking an ice cold drink during the test, ideally from an aluminum container to improve heat transfer. 

As a practical matter, fan cooling will be needed to hit your targets.


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## Techjunkie (Jun 3, 2010)

BigC,

I think you'll do fine with Aluminum. That much copper is super heavy. Also, that much copper will store a lot of heat and take a helluva long time to cool down - probably not ideal if you find yourself in a situation where your emitter is at the overheating point. With the heatsink that tall/long, you'll want to bore out the bottom, maybe in steps, or even in a cone shape. That'll reduce the weight but not the surface area, so It'll transfer heat to the host just as fast without storing as much of it.

For the emitter mounting, you've got to go with a star board, silver thermal grease and tap some screws for the best possible heat transfer. Paste is OK, but not nearly as good. As you know from your sphere testing, heat robs you of lumens, so you want to shed it as fast as possible.

Don't use 4 cells in direct drive - you'll make popcorn of your SSR-90! (Especially with 20awg wire and other electrial resistance reductions.) My recommendation for direct drive is to go with 3 AccuEvolution LSD NiMH C-Cells and reduce resistance in the switch by cleaning the parts with steel wool and then treating with de-oxit. Sink a Mag shorty gold spring from KD into the tailcap (deano'd on the inside with drain cleaner) and you'll be sure to pull 9A+ from the LED. The Mag switch can certainly handle the current.

If money's no object, then you could go with a DerWichel 9A regulator and 3 AW IMR26500 cells instead, and have a constant 9A for the entire battery discharge. I've yet to try that myself, but only because spending >$100 on just the batteries and driver vs. ~$20 on the NiMH cells doesn't appeal to my frugal nature.

Thanks to Hill and ti-force for the mention. I feel like I've "arrived" when I see people do that in threads I didn't even know existed.  Thanks to CPF, I'm _internationally known_


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## flashfiend (Jun 3, 2010)

Why would you need 3-LiIons to drive 1 regulated LED?


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## FroggyTaco (Jun 3, 2010)

Techjunkie said:


> BigC,
> 
> I think you'll do fine with Aluminum. That much copper is super heavy. Also, that much copper will store a lot of heat and take a helluva long time to cool down - probably not ideal if you find yourself in a situation where your emitter is at the overheating point. With the heatsink that tall/long, you'll want to bore out the bottom, maybe in steps, or even in a cone shape. That'll reduce the weight but not the surface area, so It'll transfer heat to the host just as fast without storing as much of it.



Could you elaborate on why you believe the copper is gonna take a "long" time" to cool down. I could see that with just a copper slug & no real way to dissipate the heat. But when the heat is gonna transfer to the flashlight body & and be heatsinked from the hand holding the light I don't see the copper slug becoming heat-soaked.

Travis


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## Techjunkie (Jun 3, 2010)

flashfiend said:


> Why would you need 3-LiIons to drive 1 regulated LED?


 
As long as they fit in the host, you'll have more capacity/runtime, and by having pack voltage greater than Vf for the entire discharge, you'll have buck regulated constant output for the entire runtime (unlike a direct drive setup).



FroggyTaco said:


> Could you elaborate on why you believe the copper is gonna take a "long" time" to cool down. I could see that with just a copper slug & no real way to dissipate the heat. But when the heat is gonna transfer to the flashlight body & and be heatsinked from the hand holding the light I don't see the copper slug becoming heat-soaked.
> 
> Travis


 
Among two like sized/shaped pieces of copper and aluminum, the copper piece, besides being heavier, has the capacity to store more heat. My statement assumes that both heatsinks will have the same thermal contact to the host and therefore will transmit heat to the host at the same rate. The one with more heat stored will take longer to shed all its heat in the same way that a heavier frying pan will stay hot longer than a lighter frying pan after both are removed from the range. This is all just theory based on my observations with various aluminum, brass and copper heatsinks used in my recent SST-50 projects (and my experience with frying pans :laughing: ).


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## flashfiend (Jun 3, 2010)

Don't you reduce efficiency with more cells? (Depending on the driver, of course)


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## Stereodude (Jun 3, 2010)

flashfiend said:


> Don't you reduce efficiency with more cells? (Depending on the driver, of course)


Yes, generally speaking, the larger the gap between Vin and Vout the less efficiently the driver runs. Still, it beats the alternatives.


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## flashfiend (Jun 3, 2010)

So some of that extra power goes to heat right?


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## Techjunkie (Jun 3, 2010)

flashfiend said:


> Don't you reduce efficiency with more cells? (Depending on the driver, of course)


 
It depends on the driver. The Der Wichtel 9A driver that I mentioned is 90-98% effiecient up to 20V input. Instead of the three IMR C cells, I suppose two LiFePO4 D cells or two IMR 26650 cells might provide the same runtime / capacity, although I trust AWs capacity rating more than the latter two (which both claim 4AH per cell).

Also, here's a good thread about heatsink mass and heatsink vs. heatspreader design:
https://www.candlepowerforums.com/threads/253367


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## ti-force (Jun 3, 2010)

flashfiend said:


> So some of that extra power goes to heat right?



Yes, waste heat. In a situation like this though, the benefits outweigh the side effects . Like medication


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## Stereodude (Jun 3, 2010)

flashfiend said:


> So some of that extra power goes to heat right?


Yeah, but it's not a lot and there are other significant benefits. The bottom line is that when it comes to batteries your options are somewhat limited if you're trying to not exceed 2 cells in series. You could get 2 5.2Ah "D" Li-Ion from KD, but that's the largest I've seen single cells. Or, you could do 2S2P with 18650's in a bored mag, but that's still only 5.2Ah. On the other hand, if you went with 4 LiMn 4.0Ah 26650 cells sure you'll lose a few % on the efficiency side in the driver, but you've got 64% more battery capacity than the 2 KD "D" cells or a 2S2P 18650 setup.


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## PCC (Jun 6, 2010)

Hey, BigC, the batteries I mentioned the other night have a manufacturer-rated max discharge rate of 70A (!) so I don't think that those cells will be a problem. Four of them with a resistor might be what you're looking for. Three of them DD might work as well but the resistance from the host is the biggest obstacle that I see for this project right now.

What would be the best route for a low resistance switch or this monster? The stock Mag switch probably can't handle the strain, at least not in the long run. Any other ideas?


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## bigchelis (Jun 6, 2010)

PCC said:


> Hey, BigC, the batteries I mentioned the other night have a manufacturer-rated max discharge rate of 70A (!) so I don't think that those cells will be a problem. Four of them with a resistor might be what you're looking for. Three of them DD might work as well but the resistance from the host is the biggest obstacle that I see for this project right now.
> 
> What would be the best route for a low resistance switch or this monster? The stock Mag switch probably can't handle the strain, at least not in the long run. Any other ideas?


 

Cool. Let me get this heatsinks back and I will PM you for a possible meet where we can see what my particular SSR-90 pulls with 3 NiMH cells. If it pulls low current like 3~5A, then we will have to use 4 of those cells and put the resistor in the switch.

I will PM you as soon as I get any update.

bigC


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## PCC (Jun 6, 2010)

Sounds good. What about that big heatsink idea?


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## js-lots (Jun 14, 2010)

bigchelis said:


> Cool. Let me get this heatsinks back and I will PM you for a possible meet where we can see what my particular SSR-90 pulls with 3 NiMH cells. If it pulls low current like 3~5A, then we will have to use 4 of those cells and put the resistor in the switch.
> 
> I will PM you as soon as I get any update.
> 
> bigC



I too am currently in the market for a maglite mag with a sst/ssr 90 However I a really stuck on form factor. The options out there for a direct drive in a maglite 2c is either a 26650 or three 4/5 sub c nimh. My problem is no one is really sure what kind of amps a sst 90 can draw from the three 4/5th sub c nimh's and how long. There is plenty of info on the on the single lion setup but not the nimh. Anybody have any further insight on this? I really want to get this project going. Thanks


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## bigchelis (Jun 15, 2010)

js-lots said:


> I too am currently in the market for a maglite mag with a sst/ssr 90 However I a really stuck on form factor. The options out there for a direct drive in a maglite 2c is either a 26650 or three 4/5 sub c nimh. My problem is no one is really sure what kind of amps a sst 90 can draw from the three 4/5th sub c nimh's and how long. There is plenty of info on the on the single lion setup but not the nimh. Anybody have any further insight on this? I really want to get this project going. Thanks


 

Sorry, but from what I have seen the current is a coin toss. Although Nailbender seems to be getting lucky with his Mag builds and super current levels.

A 2D with 3 NiMH Tenergy 5000mAh C cells is the route I will go and if I get ideal conditions = 9~10A :candle:


SSR-90 6500k is what you need for max lumens. If you get the emitter by itself with no star then heatsinking will not be as ideal.


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## ma_sha1 (Jun 15, 2010)

bigchelis said:


> Sorry, but from what I have seen the current is a coin toss. Although Nailbender seems to be getting lucky with his Mag builds and super current levels.
> 
> A 2D with 3 NiMH Tenergy 5000mAh C cells is the route I will go and if I get ideal conditions = 9~10A :candle:
> 
> SSR-90 6500k is what you need for max lumens. If you get the emitter by itself with no star then heatsinking will not be as ideal.



I can't imagine 3 NiMH could get to 9-10A. 
I got 8 Amp using 4x 4/5 Sub C NiMH (In a 2D Mag), DD with tail cap resistance mod. Battery are 1.38v each freshly charged. Perhaps bigger Sub C could get to 9A, Full size C NiMH may get to 10A, but I would imagine it'll take 4 of them, which would not fit your Mag 2D plan. 

Previously, I made a 4AA Eneloop DD SST-90, also got 8 Amp. I am using the same meter as you.
I've seen some posts with cheap meter/thick wire trick & some Amps appears inflated.

Also, I am not sure you can fit 4 Sub C in Mag 2D, I used smaller 4/5 sub C, there's may be 20mm room left to bottom.
The regular Sub Cs are 10mm longer than the 4/5 Sub C, so 40mm longer total & possibly 20mm too long.


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## Techjunkie (Jun 15, 2010)

oops, posted in reponse to 2C while thinking 2D... deleted.


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