Green Led No Like 14500 Host?

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Hank33
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Green Led No Like 14500 Host?

Yesterday I found a pkg I forgot about and it contained aSST20 green led, IR driver and a 14500 host. Put it all together and it doesn't work.undecided

All the solder and retaining rings seem to be good contact. Could it be because the 14500 battery not enough juice?

MtnDon
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I almost always try a new led/mcpcb and driver outside the light before assembly. I have a finned aluminum heat sink I use as a temporary mount for the mcpcb.

I sort of don’t think it is the cell though, so I would try the driver with another led/mcpcb or that led/mcpcb with another driver.

I have an 18650 in a cell holder complete with a 4056 charger all set up on a board to make such testing easy as can be.

Marc E
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I wonder if it’s to do with that output voltage being variable between 1.4 – 3.6 volts.
I don’t know either how the driver works or what the forward voltage of a green SST-20 is, but it’s possible that with single li-ion battery the driver isn’t putting out enough voltage to power up the LED.

Mark M
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That LED data sheet says minimum voltage is 2.8v. What is the driver putting out? Hopefully not 1.4v. Other obvious things would be mixing up the positive and negative connections, I know I have mixed them up before.

Hank33
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MtnDon wrote:
I almost always try a new led/mcpcb and driver outside the light before assembly. I have a finned aluminum heat sink I use as a temporary mount for the mcpcb.

I sort of don’t think it is the cell though, so I would try the driver with another led/mcpcb or that led/mcpcb with another driver.

I have an 18650 in a cell holder complete with a 4056 charger all set up on a board to make such testing easy as can be.

Yeah a test rig is a good idea. I was actually contemplating setting up an external testing rig for leds and mcpcp etc. Got lots of pc fans and battery mounts and charging boards. Way easier than soldering, then pill unscrew, then pill screw, then desoldering, then testing, then pill unscrew,then soldering, then desoldering, then soldering again, then washroom, then pill unscrew, then soldering. Then there’s the thermal paste that needs cleaning and replacing plus it gets in everything.

Mark M
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Use a multimeter to test the voltage going to the mcpcb. This will let you test polarity and if you have voltage and if the voltage is enough to drive the LED.

MNLegoBoy
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Marc E wrote:
I wonder if it’s to do with that output voltage being variable between 1.4 – 3.6 volts.
I don’t know either how the driver works or what the forward voltage of a green SST-20 is, but it’s possible that with single li-ion battery the driver isn’t putting out enough voltage to power up the LED.

Probably, data sheet says 3.4 typical. but 4 is a maximum, and with a 1 amp current, it would probably raise that above 3.6
Hank33
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I think Vf for green led is around 2.8v. The driver I have is the 1400mA one. Seems to be good enough juice but gonna have to switch to an S2+ host and a 18650 to see how it goes.

Mark M
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No voltmeter/multimeter? It would be way easier to test… it doesn’t matter what current that driver is putting out if it isn’t reaching the forward voltage threshold of the led to get the current to flow.

moderator007
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The resistor marked R220 should be setting the current at 1.4 amps with what ever voltage the led needs to make that current. Unless its outside the drivers capability.
The resisitor could be changed up or down in value to change output current.
A simple amc7135 driver with 4 chips would do about the same thing in output and would have the ability to be flashed with some custom firmware.

Hank33
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I have a multimeter that I can test with. Just that my work table was overflowing with stuff. I’ll chk it out later.
I guess down the road I can also try a resistor mod but that means ordering and who knows how long it’ll take to get here nowadays?? Maybe after summer?

Hank33
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Oh 2.5v but I believe green leds need around 3.2v. So yeah that won’t light up. Yeah I’m gotta do some math too later on. It’s go Green or Bust day! Cool

Lightbringer
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A multimeter’s “diode test” usually puts out enough current to get a faint glow out of LEDs, so that’s a quick way to test if the LED’s live (and the readout will show the voltage).

Switch to voltage (eg, 20V), then power it up. If it reads negative, then the LED’s installed backwards.

09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

Hank33
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Well I did chk and + – ok so I think might be the host itself. Gonna go chk that next.

Hank33
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Uh so I had a moment just now to chk it out again and alas, it works! The thing is I have to unscrew the tailcap almost 90%. Big Smile I then checked continuity on the treads and sure enough it only registers at the 90% part. Could it be the paint is too thick or something on the threads?

e1000
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battery tube backwards?

Hank33
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e1000 wrote:
battery tube backwards?

The tube is correct I believe. I tried it the other way and it wouldn’t screw in. I think I’ll try sanding the coating off the tail end and see what happens.