Unsure what's going on with my mtg2

pinkpanda3310 · Apr 23, 2013

I made up a copper slug (terminology??) for the mtg2 to run direct drive in my z2. I'm not good with soldering so I had a few issues along the way. I had a couple of shots at soldering the led to the copper because I used a little too much solder first time and it basically flooded the back of the led. So I'm thinking I may have overheated the led but don't really know. Another problem I had was I used a small spring clamp to hold the led and when the heat got into the led the first time the clamp stripped the dome off.:ironic:

I thought it was completely stuffed at that point but when I tested the led it still worked. So I continued to mount the led with negative and thermal pad soldered to the copper slug and positive to the spring at the rear of the slug. Install into the host, it works:huh:

Very warm colour and smooth floody beam profile but not quite the output I was expecting. I'm using the 2x surefire 123a batteries and wondered if they weren't coping but they hold higher volts and amps when connected to an sst-90. The measurements I got were 1.6v and 0.16a on the mtg2.

What happened? Did I cook the led? I understand it cannot be fixed, I just want to know so I don't repeat the same exercise with another led. Any help/advice appreciated.

pinkpanda3310 · Apr 23, 2013

I took some pics with my phone so they are no the best.

The colour is not quite as yellow as pictured.

TEEJ · Apr 23, 2013

pinkpanda3310 said:
I made up a copper slug (terminology??) for the mtg2 to run direct drive in my z2. I'm not good with soldering so I had a few issues along the way. I had a couple of shots at soldering the led to the copper because I used a little too much solder first time and it basically flooded the back of the led. So I'm thinking I may have overheated the led but don't really know. Another problem I had was I used a small spring clamp to hold the led and when the heat got into the led the first time the clamp stripped the dome off.:ironic:

I thought it was completely stuffed at that point but when I tested the led it still worked. So I continued to mount the led with negative and thermal pad soldered to the copper slug and positive to the spring at the rear of the slug. Install into the host, it works:huh:

Very warm colour and smooth floody beam profile but not quite the output I was expecting. I'm using the 2x surefire 123a batteries and wondered if they weren't coping but they hold higher volts and amps when connected to an sst-90. The measurements I got were 1.6v and 0.16a on the mtg2.

What happened? Did I cook the led? I understand it cannot be fixed, I just want to know so I don't repeat the same exercise with another led. Any help/advice appreciated.

OK, so you have a de-domed MTG2...sweet....albeit possibly a bit overdone heat-wise.

I'd guess that the 123a's can't support the amp draw that that LED needs for full brightness, maybe use 18350's instead?

You want closer to 5-6 AMPS, and can go up to 8.4 volts.

Two 123's are going to give only 6 volts and a teeny trickle of amp juice...not the 5-6 amps you need.

Even the RCR123's (16340's) are not able to handle that power draw...the 18350's are about the smallest two cells that will power than LED with full output.

At 8.4 v and 6 amps, that LED can be pumping out more like 3,000 lumens.

I'll make a wild guess that, as dedoming can reduce OTF lumens, while making the beam tighter, you might not get the full 3k lumens...but you might get some more throw at least.

pinkpanda3310 · Apr 23, 2013

The batteries can handle it. I got something like 3.(something)v and 3a when connected to the sst-90.

TEEJ · Apr 23, 2013

pinkpanda3310 said:
The batteries can handle it. I got something like 3.(something)v and 3a when connected to the sst-90.

3a ≠ 6a

3.0 v ≠ 8.4 v

So, anyway...that's at least one reason its dimmer than expected....it takes more power than the sst-90, and than those 123's can provide.

Would you try two IMR 16340's? (IMR's MIGHT give too much amp flow, but would give enough voltage...but its for proof of concept, if not POOF of concept)

I'm guessing your host isn't able to fit 18 mm cells?

If its brighter with them, then, its the cells....and the 18350's would therefore be even better, etc.

Do you have a way to simulate a power supply to it to recreate what cell combinations would look like out put-wise?

Justin Case · Apr 23, 2013

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Justin Case · Apr 23, 2013

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pinkpanda3310 · Apr 23, 2013

6v 3000k was what I ordered. If it was 9v or 36v I would think the led would not illuminate since Vf would be too low.

Other battereies I have are only 18650's (which I will try when I get home, thanks fo rthe idea) and 4x eneloop AA's (This would be too current me thinks).

TEEJ I don't follow your volts and amps calculation, can you dumb it down for me.

pinkpanda3310 · Apr 23, 2013

'Human eye Intergrated shere' LOL

The stock surefire incan module delivers a nice spot that maybe throws a little further but the mtg2 seems floodier and overall a few more lumens.

TEEJ · Apr 23, 2013

That LED (9v) should be able to pump out about 3,000 lumens at 8.4 volts and 6 amps....that would be more than say 300 lumens.

If you only WANT a few lumens, sure, call it a day...but you went direct drive, which for most people, meant you wanted balls to wall LIGHT.

Most of us have eyes that SUCK at judging lumen out put, partly because we can't SEE lumens, we can only see the lux created on targets, etc.

So a throwier pattern LOOKS brighter, as it makes more lux (The lumens are all hitting a smaller, brighter spot).

For the enloops, hmmm...1.4 volts times 4 = 5.6 volts, nope, low enough on voltage at least.

Justin Case · Apr 23, 2013

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TEEJ · Apr 23, 2013

Is it possible to create a good current/gound path to the LED and see if it helps?

Justin Case · Apr 23, 2013

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pinkpanda3310 · Apr 23, 2013

The surefire cells measure 5.7v together unloaded, I'm not sure what they are meant to be when fresh. Maybe my human eye intergrated shere does need calibration. I still wonder about the posibilty of parasitic resistance though. Like you mentioned what does dedoming do for it? I also wonder if my poor soldering efforts have changed something in the led itself. When I get tonight I will try an 18650. Thanks for the help guy's.

As far as a good ground path, I have connected the cells to the slug outside of the host to get the best connection, same result.

Justin Case · Apr 23, 2013

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pinkpanda3310 · Apr 23, 2013

Oooh..... but even still, the batteries still held up better when powering an sst-90??

pinkpanda3310 · Apr 24, 2013

So tonight I tried to power up with a half charged 18650. Nothing. It worked a second ago with the 2x surefire bat's. So I tried one half charged and one flat 18650 in series getting just over 7v unloaded. BAM! got the wall of light I was hoping for. :party:

I checked the current and was getting 2.4a. Okay, so it's the batteries, kudos to Justin. I put the light back together and make a note to source some decent batteries. Light back together with surefire cells, test... nothing! On top of that the cells were warm like they were working hard. Take it apart again and test with the 18650's... nothing! AARRGGHH!:duh2: There is definitely a circuit because there is small sparking if I slide one of the connections. I guess my options have opened up now :ohgeez:

Thanks for the help anyway guy's.

Justin Case · Apr 24, 2013

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pinkpanda3310 · Apr 24, 2013

Yes, it was 2x 123A cells on the sst-90.

Justin Case · Apr 24, 2013

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Unsure what's going on with my mtg2

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