Direct drive an SSC Led in a 2D mag?

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davenlei

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I was thinking of buying a 2D mag and direct driving the 'D' cell batteries (2x1.5v) to a SSC LED I was going to affix to a solid piece of copper where the regular bulb went.
Will this work? What will the current be to the LED if this is possible? Will it fry the emitter after it heats up due to the thermal conductivity issue?

I am just trying to see if I can get even more light out of an SSC in a Mag than my current SSC modded 3DMagLED module.
 
davenlei said:
What will the current be to the LED if this is possible?
Click to expand...

I don't know if SSC publishes accurate forward voltage curves in their datasheets. If so, it would give you some idea of how much current (and thus how much brightness) to expect.

I have measured the current drawn by a Cree P4 star when directly driven with two cells (3.2 volts). The Cree's specs should be similar the SSC part - It measured almost exactly 0.03 amps (30 mA).

(BTW, even at this low current, the LED produced quite a bit of light in comparison to most 5MM LEDs - very efficient little suckers! - but nowhere near the kind of brightness you're looking for. Naturally, the star stayed cool to the touch.)

BOTTOM LINE: My guess is that even 2 brand-new cells won't provide enough voltage to drive the LED at anywhere close to maximum brightness.
 
Last edited:
ah, I see. And running it direct in a 3 cell will burn the LED out unless I put a resistor in line right? The downside would be that I am burning up energy by heating the resistor.
 
Yeah, unless you use a driver board, you'll need three cells to get the SSC up to the brightness you're probably expecting. You do know the issues with focusing an LED in a Mag mod, I hope. It really needs to be mounted at the exact right spot to get any sort of decent focusing. Usually with a custom made mod, an O-sink will be used which is a large heatsink which puts the LED at the right height. Then the reflector needs the cam cut off of it.

The nice thing about using a board is you get consistant output over the life of the batteries. The nice thing about running direct drive is, though the output dims, you can get CRAZY long runtime of the lower output. I'd guess something like 24 hours of decent brightness then another 3 days to maybe a week of lower output.
 
If you already have a 2D maglight, you can either buy a boosting circuit---or put 3 C cells in it, and resistor it down. I haven't done it in a while, so I might be confusing this with some other battery configuration I've tried but if I remember right you just deannodize the inside of the tailcap and then turn the spring around to make room.

Don't get too intimidated about using your own heatsink. There is enough room between the switch and where the LED needs to be, so if you put it too high, you can trim things down and try again. Also, although there is a very fine line between being in focus and looking awful---maglight was kind enough to make a rather long threaded area between the head and the body. This translates to a certain amount of grace in adjusting the focus.

You'll need tocut the cam off the reflector for clearance.

One suggestion I'll give you if you're making your own heatsink: If you set it ontop of the black plastic bulbholder---that plastic is real easy to cut with a utility knife--so you can slowly keep cutting it back until you've got it where you want.

You may want to power one up and stick it close to the hole of the reflector so you can get a good feel for roughly how high it should be before you start.

Anyway you do it though---this will be an inexpensive, good throwing light.
 
Cool. I have already modded my MagLED module with an SSC LED and it is crazy bright. I just don't like the reduction in brightness 10 minutes after turning it on due to the throttling down of the current due to the unit heating up. I wanted to bypass that 'feature' and also give the LED it's full 1000ma rather than the 700ish ma that the MagLED module puts out.
 
If you want to do that, then modify the mag itself. Get a DHS heatsink or hotlips/etc and mount the SSC down. Then get a circuit to regulate 1000ma to it. That way it will be bright and stay cool.

Nothing beats well modded mag. Gives you pride that you built it and the heat sinking lets the led shine to it's full potential safely. :)
 
Ok, sounds good. So I have a listing in the buy section of the site looking for all those things.. :grin2:

Can't wait to do the mod.
 
Hmm...Alot of luxeons handled being direct driven with 3 alkalines just fine. Are the crees and ssc's more fragile?
 
Hey D, i just completed a 3D mag conversion to led and used
- one seul led
- one gd750 (from the shoppe)
- one hotlips sink.

It was my first one and quite straight forward. I keped the current to 750ma for 2 reasons. First the increase in brightness was not realy needed and would not be that noticable. Second, standard alk's lose out in internal resistance at around 1A, so 750 was a good compromise.

Did a runtime test on alks, it has run for 10hrs and is still going strong... will resume the test tonight :)
 
Minjin said:
Hmm...Alot of luxeons handled being direct driven with 3 alkalines just fine. Are the crees and ssc's more fragile?
Click to expand...

I think it's more of a matter of Crees and SSC's having lower forward voltage - which means that they draw a lot more current for any given supply voltage.
 
Whether it will work has to depend on the Vf of the specific LED thats' to be used. An LED that has a low Vf will burn up if you use too much voltage.

I have an SSC P4 that pulls 1 amp at 3.7 volts. It would burn up at 4.5 volts. You can buy an L or M binned lux III will do OK on 3 C cells.

It's not BAD to burn off excess power with a resistor when the voltage is close to correct. Using a higher binned Vf instead of a resistor in direct drive uses exacly the same amount of energy. If the voltage diference is large, a down converter is likely to be more efficient.

Daniel
 
Don't forget you need to isolate the emitter base on an SSC LED !
Litemania has some anodised SSC mag C or D heatsinks for sale in the dealers section.
I've been planning to make one soon myself, staying with two D cells, and using a pair of Micropuck drivers (http://www.leddynamics.com/LuxDrive/content/Page_Micro_App.html)
to give approx 700-800Ma to the SSC. There so are many ways to make the same thing. Let us know how you get on.
 
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