3v power - help choose emitter

[Asusvivobook]

Hello folk.
I'm searching for a low-volt 3535 emitter

I bought these (519a, xpl-hi, xpg3). They're great at 3.7v but my flashlight only gives me 3v. Most of those LEDs suck at low voltage, very little lumens.

What should I try next?

 

[LEDphile]

The I-V curve of semiconductors and the relationship between bandgap and emitted wavelength means that you aren't going to get significant current through anything with a shorter wavelength than green with only 3V. And even green is dicey as most of what's commercially available is not as advanced as the blue epi.

 

[desert.snake]

Hello folk.
I'm searching for a low-volt 3535 emitter

I bought these (519a, xpl-hi, xpg3). They're great at 3.7v but my flashlight only gives me 3v. Most of those LEDs suck at low voltage, very little lumens.

What should I try next?

Large companies usually have a voltage division of diodes within a series, like Nichia and Cree do, but what you get in reality is may be a lottery. What kind of flashlight do you have, does it have a driver or does it just have a battery that connects to a LED?

For example, 519A can easily produce ~1 ampere at 3 volts, it's quite bright

I remembered that on the Digikey website you can specify the diode size and voltage in the search, maybe this will help

in size 3535 the lowest voltage showed me 2.7 volts, these

https://www.digikey.com/en/products/detail/creeled-inc/XPGDWT-BF-0000-00KE5/22983544

 

[Asusvivobook]

The I-V curve of semiconductors and the relationship between bandgap and emitted wavelength means that you aren't going to get significant current through anything with a shorter wavelength than green with only 3V. And even green is dicey as most of what's commercially available is not as advanced as the blue epi.

I kinda understand and I thank you for the reply.

I should mention that the flashlight came with an xpg3, It gives enough lumens, but the tint is pretty bad

 

[Asusvivobook]

What kind of flashlight do you have, does it have a driver or does it just have a battery that connects to a Led

https://www.digikey.com/en/products/detail/creeled-inc/XPGDWT-BF-0000-00KE5/22983544

I'm working with the flood portion of a Fenix hp25r. It's got a driver. I'm not sure about Mah, but I measure 3v.

That link shows me an xpg3 which was a exactly what the light came with. Maybe Fenix realized that that's the best choice.

I'm hoping you folk can best Fenix, and prove them wrong. Help me find a better emitter 😁

 

[desert.snake]

I'm working with the flood portion of a Fenix hp25r. It's got a driver. I'm not sure about Mah, but I measure 3v.

That link shows me an xpg3 which was a exactly what the light came with. Maybe Fenix realized that that's the best choice.

I'm hoping you folk can best Fenix, and prove them wrong. Help me find a better emitter 😁

Judging by the description of the model, there are 3 different LEDs - Luminus SST40 for throw beam, XP-G3 for flood beam and Everlight 2835 for red beam. Do you have any desire to also change the SST40 for something more pleasant?

It's hard to beat the XP-G3 now, unless select from different XP-G3s that have the lowest Vf characteristics, as we found on that site. If you want a more pleasant light, you will have to put up with less brightness. I recommend try Nichia 519A R9080 with the color temperature that you like

Also recommend you visit BLF (budgetlightforum), there are sooo many flashlight modders there and they are very knowledgeable about the latest LED innovations. There's a real treasure trove of wisdom of the modding lights especially modern Chinese flashlights

 

[jon_slider]

(519a, xpl-hi, xpg3). ...very little lumens.

What should I try next?

the things that increase lumens are

1. Low CRI (that rules out the 519a)
2. Cool White color temperature, look for options above 5000K, for example this 7500K or 6500K XP-G3

unfortunately, there is a trade off between more lumens quantity, vs more color quality

the LEDs with the most lumens have ugly green tint, harsh blue color temperature, and poor color rendering (especially in Red)

> They're great at 3.7v but my flashlight only gives me 3v

the Voltage of the LED is not the primary factor controling its brightness
...
it is normal that the flashlight gives 3V to the LED.. that is not what makes them less bright. Fenix decided how much current (Amps, not Volts), to send to each LED in your light. They chose a Power level (Watts), they think is bright enough for the role of each LED, while still retaining acceptable runtime. You can not change any of those factors.

you can change the LED, but there are tradeoffs.
LEDs become less bright when the underlying blue LED gets coated with a phosphor layer..

to make an LED, less green tinted, less blue color temperature, and give better color rendering, requires increasing phosphor density, at the expense of less light transmission..

Maybe this is a perfect excuse to search for a new light you might want to buy ;-)

 

[Dave_H]

I'm working with the flood portion of a Fenix hp25r. It's got a driver. I'm not sure about Mah, but I measure 3v.

That link shows me an xpg3 which was a exactly what the light came with. Maybe Fenix realized that that's the best choice.

I'm hoping you folk can best Fenix, and prove them wrong. Help me find a better emitter 😁

LEDs are current-driven devices. LED voltage reflects what it is for that specific LED at that current the driver supplies; and temperature. The driver may be able to deliver higher voltage to a different LED. You would need to get driver specs (if possible?) or do some testing.

Datasheet LED I-V curves are usually typical. Vf ranges are "bins". Getting the bin you want in small quantity may or may not be workable. Binning also includes brightness and CCT. The economics of yield do not allow the vendors unlimited flexibility in what they offer. You might get what you want/need from DigiKey, Mouser etc., don't know, have not tried.

Dave