0.5w uv led

[TheLonelyNoble]

I'm having some trouble with a 0.5W UV LED that I ordered off ebay. This specific LED has 5 dies inside its lens, but the problem I'm having is that only 2 of the dies
are lighting up. The other 3 light up for about half a second when I connect the power, but not afterwards. I know that they haven't burnt out because they light up for that half second every time without fail. I thought it might be a lack of current, but the battery I'm using is capable of 14.5 amps and this LED supposedly only requires 100ma so I'm at a loss as to what the case may be.
Any help/ideas would be greatly appreciated.
Here is the listing:
1P High Power 0 5W 5 Chips 10mm UV Ultra UV LED Lights Lamps 40KMCD | eBay

Thanks all

 

[FireMyLaser]

It's a bad, low quality LED. It's broken. Don't bother getting another one just like it, because it will also fail. Instead, get a 1W smd LED with a SINGLE die.

 

[Cyparagon]

I'll give this a 95% chance that there's a problem with the way you're driving it.
So... how are you driving it?

 

[TheLonelyNoble]

It's a bad, low quality LED. It's broken. Don't bother getting another one just like it, because it will also fail. Instead, get a 1W smd LED with a SINGLE die.

If that's the case, it only cost me 1 cent + shipping, so it's not too big of a deal.
For an SMD, is there any particular brand you'd recommend?

I'll give this a 95% chance that there's a problem with the way you're driving it.
So... how are you driving it?

I'm using an LM317 Adjustable Regulator at 3.6v hooked up to a 3.7v 18650 LiPo. I'm wanting to fit it in a relatively small housing which is why I don't want to over complicate it.

 

[FireMyLaser]

An LED needs constant current, not constant voltage. Even so, your 3.7V (4,2v) battery is not enough for an lm317 constant current driver, you'd need about 7V. Though you'll be fine using just a simple resistor, look for an LED resistor calculator on the web. Any 1W uv LED should be fine enough. Through-hole UV LEDs are notoriously low quality and very short lived.

 

[Cyparagon]

Just as I though :yabbem: You need to configure your LM317 to operate in constant current mode, and you need to at least double your input voltage. This is not a suggestion, this is a requirement for proper operation.

 

[TheLonelyNoble]

Ahhh I see. I'll give both suggestions a try, and come back with the results.
Thanks all

 

[chipdouglas]

His diode voltage is 3.6. Couldn't he just use a 6ohm 1/4 watt resistor and a fully charged lithium ion battery? I thought LEDs where much hardier than ld's.


Michael

 

[Cyparagon]

I didn't say half-ass n00b operation, I said proper operation. :beer:
A resistor would power it fine for a few seconds, but then the power drops as the cell drains and he's back to square one.

 

[chipdouglas]

Oh =p

 

[TheLonelyNoble]

After trying the suggestions, I've found I'm still having the same problem and have come to the conclusion that the LED itself is the problem..
Thanks all for the help anyway.

 

[EnergyCoherence]

I'm having some trouble with a 0.5W UV LED that I ordered off ebay. This specific LED has 5 dies inside its lens, but the problem I'm having is that only 2 of the dies
are lighting up. The other 3 light up for about half a second when I connect the power, but not afterwards. I know that they haven't burnt out because they light up for that half second every time without fail. I thought it might be a lack of current, but the battery I'm using is capable of 14.5 amps and this LED supposedly only requires 100ma so I'm at a loss as to what the case may be.
Any help/ideas would be greatly appreciated.
Here is the listing:
1P High Power 0 5W 5 Chips 10mm UV Ultra UV LED Lights Lamps 40KMCD | eBay

Thanks all

LEDs can still light even if they are damaged.