# 4w, 5w and 6w LED. (Newb question)



## arbiter (May 31, 2010)

So i'm searching for some 6w LED, i have found 3w but wondering if anything higher than 3w is even available currently on the market in the standard 3mm-5mm type bullet LED.

any information regarding this would be helpful.

so 'wattage' heh, or Current is just the voltage (forward?) going through LED
so if i take 2 3v watch batteries in series and connect the LED to that power source and the LED doesn't blow, does that mean that the LED is a 6w LED?

how can i look at watts in relation to voltage in regards to LEDs.
i'm quite new to these electronic concepts but i'm trying to teach myself.

again any information or help in this regard is greatly appreciated.


----------



## John_Galt (May 31, 2010)

arbiter said:


> So i'm searching for some 6w LED, i have found 3w but wondering if anything higher than 3w is even available currently on the market in the standard 3mm-5mm type bullet LED.
> 
> There are LED's that can be classified as "6watt" LED's, however, this is a poor classification system for LED's. Please understand that Power (in watts) is volts x Amps. Volts being the forward voltage of an LED, which is usually around 3.5-3.7volts. (this voltage can be lower, in some newer, more efficient LED's) So, a 6 watt LED would be an LED that is driven at 1.62 Amps. An MC-E/P7 or SST50/90 LED would be in this range.
> 
> ...




Those 3, 5 and 10mm LED's are horrible for lighting applications. Look around at high power LED's from manufacturers such as Luminus, Cree, Seoul Semi-Conductor, Luxeon, etc. 

3, 5 and 10mm LED's are severely handicapped in the amount of heat they can dissipate. They tend to be made from plastics, which insulate them against removing the heat the LED die produces. Thus, to prevent an insta-poof event with them, or maintain anywhere near claimed output for a reasonable period of time, they must be driven at very low currents. Generally under 20mA, to increase lifespan. Anything greater than 75mA or so is just creating excess heat, and will cause the LED to fry.

High power LED's need heatsinking, especially if being run at greater than 50mA or so for any length of time. Heat sinking is basically creating an efficient thermal path for the heat the LED creates (which can be quite significant) from the LED die to a colder environment. Usually this is accomplished through a thermal mass and a surface area that is exposed to air.


----------



## arbiter (May 31, 2010)

I'm specifically interested in Red and Blue LED,
are these colors available in the chips you suggested?

i think the conclusion i came to is that basing LEDs of off watts isn't really logical and doesn't work so well, what matters is the Vforward and operating current yeah?

so what are some higher end operating LEDs in red and blue?


----------



## 802Chives (Jun 1, 2010)

*Wattage is: Voltage(V)*Current(A)=Power(watts)*

when talking about high power LEDs, 1W, 3W, 5W, 10W are the most common beasts. 4W and 6W may technically be right, however in regular conversation no one refers to 4w or 6w leds

Typically a high power LED is classified to a certain wattage by calculating its power in watts. A typical white LED that has a forward voltage of 3.5Vf and an operating current of 350mA is refered to as a 1W LED because: 

*3.5Vf X 0.350A = 1.225W so ~ 1W*

One should be warned that LEDs rarely operate at what they are rated for. For example a red LED with Vf=2.5V, similar to white LED example above goes like this:

*2.5Vf X 0.350A = 0.875W so ~~~ 1W*

The higher the wattage classification the worse it gets for many manufacturers. An example is a 10W classified LEDengin Red LED has a Vf=10.5V and If=700mA

*10.5Vf X 0.700A = 7.35W so kinda not really 10W*

generally speaking in my experience single emitter wattage ratings are indicative of operating current:

1W = 350mA
3W = 700mA
5W = 1A

However that tends to fall apart at higher wattages due to fact that most higher wattages are arrays and differ from one manufacturer to another in both forward operating current and forward voltages.:sick2:


----------



## arbiter (Jun 1, 2010)

Thank you 802Chives, thank you very much..
this is the kind of hard answer i've been searching for. some math to find the current output/usage.
so from here, are there any high mA rated LED's in red and blue that someone can recommend to me? or any reputable chinese online vendors (reputable as in deliver requested product in due time etc.)

thanks again.:twothumbs


----------



## Christexan (Jun 2, 2010)

To clarify further, most "watt-rated" LED products are rating the design limits of the "product", NOT the LED... 

For instance, using a Cree LED, the EXACT same LED, in 3 different "model" flashlights, one might be a "1-watt", one a "3-watt", and one a "5-watt"... it's the same LED, but the driver circuitry (and/or power source) are modified.

Most LED mfgers rate LEDs at the following "current-points" in milli-Amps or Amps... 350mA, 700mA, and 1A. They release spec sheets that show the voltage curve as it crosses those typical points (some might add other points, for instance 500mA, and 1.5A, but the first 3 are VERY common. 

An "old" white LED (2+ years ago model, or current "generic" models) might run at [email protected] = 1.12 watts (published as "1-watt" as mentioned by a previous poster, for marketing purposes). At 700mA, that LED might run at 3.6V = 2.52 watts (rounded up to "3-watts" for marketing purposes)... and at 1A, that LED might run at 3.8Vf = 3.8W= 4-watts approximately. 

Fast-forward to today, a similar, but cutting-edge LED running at 350mA might be only 2.8Vf = 0.98W (1-watt again). At 700mA, it's running at 3.2Vf = 2.25 watts, and at 1A runs at 3.5Vf=3.5 watts. 

That same LED today is electrically more efficient as you can see, it ALSO typically puts out MULTIPLE times more light at those same current points. 

So wattage (consumed) is what mfgers typically list, but it's totally misleading, lumens or milli-watts output (used often for color LEDs) is the important visual rating, and the "light-output/power consumed" is your typical "efficiency" rating. 

So an "old" white LED above running at 1A (3.8 watts) (consumed) might put out 140 lumens. A brand-new LED running at 1A (3.5 watts) puts out 280 lumens, so you get twice the light output, AND it runs longer as well (if on batteries for example, or uses less wall power, etc), even though both would probably be listed as "4-watts". 

Finally, to answer your latest response, Cree and Luxeon (I don't know about Seoul Semiconductor) both make color LED varieties, and both are typically available at Future Electronics, Arrow Electronics, Cutter (cutter.com.au), or other large electronic supply houses. 

I'd recommend reading a LOT more on this forum, and elsewhere, about LED tech though before buying anything, you have to consider soldering issues, thermal and physical design management, electrical circuit design, optical design, and many more subsets of all that, to really design anything useful around LEDs, as most power LEDs are "surface-mount" packages (can be hand-wired, with varying degrees of success and limitations) and are expected to be used with optics, diffusers, reflectors, or other optical modifiers.


----------



## doctaq (Jun 14, 2010)

dealextreme carries red crees and they did carry blue ones too but i dont know if they still have them. shipping isnt bad with express. 

i think they are the older cree xr series with a max current of 700ma but the vf is only 2.5 or so so its like a two watt led i guess. 

ive used the reds and theyre pretty good.


----------



## jason 77 (Jun 14, 2010)

arbiter said:


> are there any high mA rated LED's in red and blue that someone can recommend to me?


 I go two these three sites when I want LEDs..

http://www.newark.com/leds-high-brightness-high-power

http://www.futureelectronics.com/en/Search.aspx?dsNav=NtklainTextSearch|Colour|3|,Ny:True,Nea:True,N:915

http://ledsupply.com/led-catalog.php


----------

