Originally Posted by bkrownd
1 Watt is for a Luxeon, as in the EL500. 0.12 Watt is for a superbright LED as in the EL200. Apparently you don't understand the difference between them.
Look, for the fourth time, the point is that the best portable halogen bulbs now produce more lumens per watt of electrical input than do the best commercially available LED. That looks to change, soon, but so far that's how it is.
Your paragraph below is a sign you've finally understood that I'm saying this-- see more below-- but as far as the above is concerned, as far as there is any dispute about what I'm saying among LED adherents, *only* the newer 1w luxeons can even be argued to approach good quartz halogen in lumens/watt. The older, 20mAh LEDs lag way behind halogen in lumens/watt. There's no question about this.
A 4W LED and a 4W halogen should drain the battery at the same rate, but I doubt the difference in light output would be very large.
You don't have to guess. A good quartz halogen bulb would put out noticeably more light from the bulb compared to good 1w LED *now available* in bike lights-- but admittedly not vastly more, somewhere on the order of 8-10 lumens more. Even this would vary based on manufacturer, quality of individual bulb, etc.. This is based on a realistic estimate of the performance of commercially available 1w luxeons, which are measured independently at somewhere near 19 or 20 lumens/watt. A good halogen bulb will surpass that by a few lumens/watt, and perform somewhere in the low- to mid- 20 lumens/watt range.
Here's a link:
http://www2.whidbey.net/opto/LEDFAQ/...0Pages.html#Q7
(Then again, who knows, if ericmorin's link is correct, as good or slightly better LED may be now with us. That I would like to have tested.)
However, and it's worth making this explicit for the first time, the *reflector* on the halogen would be much better, because it could take advantage of the point source of the halogen bulb. The LED lamp, by contrast, would have to use the 1w LED in series, and so couldn't reflect all sources nearly as effectively So, as a practical matter, significantly more usable light would be put out by the halogen lamp.
This is particularly important point, since one of the things we're we're discussing is what provides the best light among lamps now, for cyclists who want to *see* the road. And cyclists like that would be interested in lamps of at least 3W-- though apparently I should be very careful to qualify this, as there are some cyclists who say they can see the road well with a 1w LED light. So, ok: all those cyclists who can see the road well with a 1w LED light shouldn't think I'm talking to them. (Similarly, all those who are not slowed by a headwind should not think I'm talking to them when I urge them to ride with the wind at their backs.)
A more interesting comparison for me would be a 1 Watt LED vs. a 1 Watt halogen - a careful measurement or calculation rather than some hand-waving nonsense based on dubious manufacturer numbers printed on a box or some website. I would be surprised if there was much difference in brightness for the same power consumption.
I wanted a 1 Watt light. It could have been a 1 Watt halogen light, for all I care, though I was willing to pay a premium for the Luxeon.
Ah. So, after all this, it turns out you don't actually have an opinion about what I'm saying in this thread: that halogen are more efficient in producing lumens/watt than LED.
Right. Good.
And it's not exactly true that you want a "1 watt light", is it? What it seems you want is a light with a very long run time, which is why you're happy with your LED during all of its battery life, even during that period when it's running at less than 1watt. (Even when it's at "half the brightness", you said.)
As I've said all along, LED do have the advantage of much longer illumination periods with the same battery energy. That's why I have mine. So, I agree with you there. But the again, I said that back in my original post.