Mag sst90 mod

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Flanders

Newly Enlightened
Joined
Dec 7, 2009
Messages
16
hi, I have just finished my first mod :)

it is a 2d mag with an sst90 on a britelumens heatsink,

i dont have any c cells right now, so i am using 3 AA's in c adaptors

i have measured the current and i am only getting .8 :(

will some decent c cells fix this? or should i be getting a bit more on nimh aa's?

anyone recommend where to get some good nimh c cells in the uk?

these are the cheapest high power nimh C cells i can find, would these be a good buy?
www.storacingproducts.com/ansmann-1-2v-sub-c-single-4500mah.html

Thanks, Stu
 
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Are you using alkalines? Give us some more info on your light. Is it a direct drive setup or do you have a driver? How much current do you want to drive the emitter with?
 
thanks for reply...

I am currently using 3 nimh AA cells direct drive.

I was hoping for atleast 4 or 5 amps :)
 
You should be getting a lot more from those aa's. It depends on the brand but I would say at least 2 amps is normal from a decent brand. Is it low in output?

Those look like decent cells. 4500mah is average for subc batteries. There was a member on here that mentioned that brand. Do a search and see what he says about them.

btw your link includes too much, erase http://.com from the beginning.
 
yes 3 in series :)

i am thinking i have a bad solder joint on the led or the switch? although the light is still bright
 
Flanders said:
yes 3 in series :)

i am thinking i have a bad solder joint on the led or the switch? although the light is still bright
Click to expand...


I would definitely check all solder joints if you're in doubt. What is the measured voltage of the adapter with all three AA NiMH's installed in the adapter? I don't have much experience using NiMH cells, but if these cells have a lot of voltage sag, I would think that might explain the problem. Again, I don't have much experience with NiMH cells, so this is just food for thought. Maybe someone else can comment.
 
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Also check your Amp meter, before I upgraded my meter, I had a cheap Multimeter
(It does have a 10A connection) that measures 1 amp when it's really 4 amps on a 26650 IMR DD SSR-90. :ohgeez:

It does better when measure 2 Li-ions/8V set-up, but useless on low volt 4-5V set-up.
The wires are too thin, my new meter now has thick wire like those used in 110v AC applications.
 
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I found when playing with a SST-90 emitter I could only get about 4.4 amps when direct driving it with 3 D size NiMH batteries. When I added a 4th D cell in 2 seconds it shot to 12.5 amps and I chickened out and disconnect. These same 3 D cells would easily push a SST-50 in the 7 amp range. I theorized that it was a combination of the Vf of the emitter and voltage sag under load of the batteries. If you are actually getting .8 amps and some lumens I would guess that the build is ok. I will take a wild guess and say it could be the adapter. What kind of 3AA to 1C adapter are you using? Perhaps try this. Fully charge the batteries and line them end to end. Now connect your meter and SST-90 emitter to them. What kind of amp draw do you have? I know from experience some of those cheap adapters out there are horrible when you start putting some decent load on them. By cheap I am not talking about the fine adapters fellow CPFers have available out there like FiveMega and Mdocod. Happy Mods!
 
thanks for all the replies!

I am just using the plastic 1xAA to 1xC cell adapters for now, I have ground out the tail cap and I am using a smaller spring to fit 3 c cells.

I only have a cheap old meter with thin leads, so I just stuck some thicker wire in the holes and it jumped up to 1.8a !

So I think I will buy a new multimeter next :)

Thanks again

Stu
 
Bingo! You are welcome.

The meter I got was referred to me by Big C, the model is:


IDEAL Test Pro Digital Multimeter Model 61-340. Cost only about $40 that I sniped off ebay NIB.


Boy, what a difference, now I can trust the readings.
 
ti-force said:
He's direct drive, so the voltage would be WAY too high unless he ran them in parallel. Maybe that's what you meant.
Click to expand...

oh of course, that would instantly fry the LED. considering its 3x the voltage. I think it'd a great move to use 14500's w/ a driver. I dont see any real advantages in having direct drive... besides not spending $12.
 
SmurfTacular said:
oh of course, that would instantly fry the LED. considering its 3x the voltage.
Click to expand...
3x 14500's wouldn't be able to provide enough current to fry the emitter, or even produce decent output from an SST90. With or without a driver.
 
gswitter said:
3x 14500's wouldn't be able to provide enough current to fry the emitter, or even produce decent output from an SST90. With or without a driver.
Click to expand...

I have a question for you. I've pulled 2.3A from a 14500 before, and that wasn't even a direct drive setup. It was a 7135 based driver, which wouldn't pull as much as a direct drive setup would it? I understand it's not safe to exceed the limitations of a li-ion cell, but it was a burst lasting less than 30 seconds. Anyway, that was with 1 cell, so wouldn't it be possible to pull more amps from 3 cells because of reduced resistance? If so, and if the cells were being ran in series in a direct drive setup, couldn't it produce a lot of light? I know it would be short lived and un-safe, but if we could draw 2.5A with a voltage of 12.6 wouldn't that be 31.5 Watts? I'm still learning here, and I've wondered this before.
 
More than likely the batteries would explode in the flashlight. The current output of batteries in series is only as much as any single cell can dish out. Basically the cells would be limited to as much current as one cell, but they would have 3 times the voltage. I think the voltage would drop similar to a power blackout because of the current draw. Think of your household wiring. It's 110 volts but relatively low current. If it was the other way around with 110 amps and 15 volts nothing would last because the current is what destroys contacts.
 
Okay, what if some resistance was introduced and the current dropped to roughly 2xc, 1.4A, and an additional 14500 was added to the mix for a total of 4- 14500's. Fully charged, we would have a voltage total of 16.8v. Would this give us roughly 23.52 watts? I understand it would have a short runtime.
 
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