DD 1 watt from 2 D's

DD 1 watt from 2 D\'s

Got some seconds and a few that are real nice (post after while of my home BINing setup....)

I want to make a very long running light on a 2 D Mag body.

I dont mind over driving it as it will be on a hot lips.

it is very bright on 2 AA's but it gets hot very quick would 3 C's work better with maybe a small resistor?

I can find any Vf ratings I'm guessing 3.5-3.7? and around 350 mA? if so the D's will be perfect and I might add a 1 -10 Ohm resistor.I may pop it off later and put a 5 watter as the prices come down as well...

Its a second so I dont mind smoking it. so I'm gonna go for It, just wont use one of the best 3...Yet.

Re: DD 1 watt from 2 D\'s

2 D's will work, but a white emitter will be disappointingly dim (but will run for a LONG time). OTOH, 2 D's with a red luxeon will be very bright.

3 C's is a better setup for a white emitter IMO. You can probaby get away with direct drive using the hotlips (YMMV).

I'm wondering how your emitter is getting hot so fast on 2xAA. Is that direct drive or do you have a badboy or madmax in there?

Re: DD 1 watt from 2 D\'s

it was direct drive.... but no hot lips...


I tried the D it puts out decnt light but only draws 290mA I dont need that long a run time...

I guess I'll try the 3 C's.

What's the foward voltage of the 1W LS rated and current?

Re: DD 1 watt from 2 D\'s

My DD 17 5mm LED draws 330mA off # C's so maybe the 1 watter will put 500mA?

what a safe but over driven current for the 1 watt?

i JUST RAN IT WITH 3C'S AND IT PULLS 400-440Ma. Thats much better.

Re: DD 1 watt from 2 D\'s

SKYWLKR,

You kind of confused me. You wish to Direct Drive a 1W with 2 D's. If it's a white, you will be underdriving it. If it's a low Vf LS, say H, it will still make a very useful amount of light for a very long time! With a hot lips, heat will not be an issue at all! I have made a few CR2 (3V) DD lights with R2H's and heat isn't an issue. They seem to run forever- just gradually get dimmer.

Larry

Re: DD 1 watt from 2 D\'s

3 posts while I was hunting and pecking /ubbthreads/images/graemlins/frown.gif .

Larry /ubbthreads/images/graemlins/grin.gif

Re: DD 1 watt from 2 D\'s

So how long will a 1 watts live being driven at 4.5 watts? it's bright.

Re: DD 1 watt from 2 D\'s

SKYWLKR,

It will last a long, long time if you remove the heat effectively. It'll burn up quickly if you don't.

Chalo Colina

Re: DD 1 watt from 2 D\'s

I lapped the LS and the Hot lips and used an extremely thin layer of Artic silver epoxy, and then used artic silver III in between the Mag body and the hot lips so I think thats about as good as passive cooling is gonna get.

whatcha think?

Re: DD 1 watt from 2 D\'s

Sounds like you've done all reasonable measures to keep the thing cool.

Using a DMM on its 10A setting, check the current using new batteries. If it's less than 1A, you are in safe, but not necessarily efficient or long-lived, territory. As the voltage drops, the current will drop faster. I think running a 1W Luxeon between 350 and 700mA (assuming good heat management) gives a good balance of light output, runtime, and LED longevity.

The objective is to figure out what current range you wish to run in and what kind of batteries you want to use, and use enough resistance that the desired current will be maintained through the "heart" of the batteries' discharge curve.

NiMH rechargeables are easiest to work with because they have a stable voltage through most of their discharge, whereas alkalines' voltage drops continuously as they are discharged. That's why LED lights tend to run brighter, longer on NiMH cells even though alkalines usually contain more watt-hours.

Chalo Colina

Re: DD 1 watt from 2 D\'s

how many lumens is a 1 watt driven that hard? close to a LS V at 1.2 amps?

and how bout 2 NhMH D's? or 3 c's?

Re: DD 1 watt from 2 D\'s

Skywlkr, you reach a point of diminishing returns. Somebody had a chart up here comparing a 1w and a lux3. Below 350-400ma, the 1w and the lux3 have essentially the same output in lumens per watt. From about 350ma up, the lux3 puts out more lumens per watt, but it doesn't amount to much below 500ma. Around 750ma, the lux3 is about 20% brighter and it (Lux3) ends up about 30% or more brighter at 1 amp. The Lux3 will also last much longer at 1 amp (20,000hrs., IIRC, from Lumileds pdf). I believe life is roughly inversely proportional to the square of the current (It actually varies based on temperature, determined by power loss, which is a square funtion)

So if Lumileds quotes a 20,000hr. life for a Lux1 @ 350ma, it will be about 2500hrs. at 1 amp. That sounds a little high, but no doubt someone will tell us where I've gone wrong. HTH, -RussH