Thanks for the info, Paul L.

At 30-40 ft/s, I'd have one second to respond if I were using LED's...

That's why I am thinking of a headlamp for descending. Also, my estimates are conservative as I have not gone out and actually measured. Maybe I will go out and measure tonight and come in with some exact figures.

What? I've never had any problem running my EL500 on NiMHs for 2-4 weeks between charges. The LED itself only requires about 3.5-4 Volts, so NiMHs should be more than enough voltage, though who knows what kind of regulator they've attached to it. It's possible you have a bad AA cell that's causing the problem.

I thought the drop in voltage = a drop in brightness with LEDs. I might have to try the rechargeables now. I thought I read somewhere they dimmed the lights on the luxeon lights. If you are not seeing a difference then I will try it I think.

There's two types, regulated and unregulated.
Regulated ones maintain the same brightness as voltage drops though I'm pretty sure current draw increases.
Unregulated ones get dimmer as battery goes down.

It depends on how the regulator inside works. Some of them will automatically dim to reduce load, and others won't. I have a pile of NiMH cells so I haven't run a set until it totally quits yet - it would be good to hook the light up to a power supply and see what happens as I ramp down the voltage. NiMHs are about 1.4V fully charged and about 1.0V mostly discharged, so I would hope it would operate down to at least 4.4V which is a good 1.1V per cell discharge. (Compare to 1.75V and 0.6V for alkaline) The luxeon requires 3.5V, plus some overhead for the regulator.

Use lithium AA's, 1.7V to the grave.

Anyone know if the light output of this is any good? With 20watts I´d expect it to be good but the low price might mean low quality.
http://www.pricepoint.com/detail/115...eam-Light-.htm

Tested my distance on my Super-spot-EL500 combo last night and I paced the farthest spotlight out to a distance of 50 - 60 feet. So that would be somewhere between 1.5 to 2 seconds at 20 mph.

I read a few reviews of that light and both of them said that the battery was basically junk.. however, i was considering buying that unit and replacing the light element with a couple of Luxeon 3s or a couple of Luxeon Vs.. now THAT'd be a system!

The III's are much better than the V's at this point, in terms of price and value.

The commercial LED bike headlights, the white ones, lose out to halogen lights in lumens-watt or lumens-$ (or euro or peso or whatever).

There's no question about this. LED white lights are worse headlights at a given time per unit of power or money.

You don't have to see any engineering papers to know this-- though any lighting engineer will tell you this, too. Compare any halogen system to a comparably powered LED light and you'll see it's no contest. Look at the camping headlamps, for example, or flashlights.

I've got the cheap 3-LED Cateye headlamp, for example, and it gets whooped in brightness-at-a-time by comparably powered halogen flashlights.

LED do have the advantage of lighter weight and *long* bulb life. Those are especially nice features when it comes to camping headlamps. I've got a Princeton Aurora headlamp and it's light enough that one can forget it's there, yet have enough soft light for close in tasks. LED are the best lights for reading in camp, too, because their light is so soft and diffuse compared to halogen bulb and reflector systems. Even now, because of their lighter weight, I like the LED lights better for camping headlamps.

For bike lights, the small Cateye LED headlamps are good be-seen lights. They're poor seeing lights, though.

The point of LED lights is their *promise*. It's expected that soon-- as in within a couple of years-- cheap LED lights will be available that wil rival incandescent bulbs in lumens per watt. (Such bulbs do now exist, they're just too expensive to produce to make LED economically competitive with the other sorts of bulbs.) With their greatly longer life, no need for reflectors, and lower heat, LED lights will be a better choice for a lot of lighting tasks then.

But LED aren't better than halogen now.

For cheap, bright light, halogen are still a better choice.

It should be mentioned, too, that the *red* LED are much more efficient than the white, and so for tail lights red LED are the best choice. (That's why commercial red tail lights are predominantly red LED, after all.)

You're making the assumption that everyone else's needs must be the same as YOURS, which is incorrect.

I own three of Cateye's less expensive LED's, but I like the EL120 for its flashing abilities. I use the flashing LED in combination with a 15W Nightstick. Although, the other day my Nightstick died on the way to work and I had to navigate the last 1.5 miles of unlit highway with the EL120. Needless to say, I had to slow down to less than 10 mph to avoid any highway shoulder hazards.

Note to self: remember to recharge Nightstick.

Well I just got an Emitter so thought I would chime in. It is much better than the 5 bulb Cat Eye I had. It is no where near as good as my 10w Halogen but for training rides on the bike path it is great. The beam is a bit narrow but not as bad as the Cat Eye. My one complain is that it is cheaply made and vibrates a bit on bumbs. Let me know if you have any questions.

Later
Matt

I don't think he's making assumptions at all. He is stating something which, for now, is a fact - current halogen lights produce more light for the money spent. Now I may decide I do not need that much light, or may prefer a smaller, cooler (pun intended) light than a halogen. Those are my needs, fine, but the fact still remains.

--J

i'm curious, folks:

I've never had a halogen light, so I don't know how long they last. Compared to an incandescent bulb, how long can one expect a halogen bulb to last? Less? About the same? Double?

Ah but is it really. If I get so many lumens per second from a halogen and it dies in three hours it could be brighter for those three hours but if my LED light last six times as long, the halogen would have to be 6 times as bright to make the claim that they were even the same cost per lumen to maintain (battery wise that is). My biggest concern in a light is length of use between recharge/battery change. The LEDs are far superior to any other light including HIDs in this category. For most of my riding the LEDs are more than suitable and nearly maintenance free (as far as recharging and so forth). It is all about what your personal needs are. If you need a stadium light for an hour ride on single track then LEDs are not for you. If you need a worry free light that gives you enough light to proceed at a moderate speed that you don't have to be constantly recharging the battery, LEDs are probably a better bet. I don't think an LED would give out enough light for a Bicycle racer, but I am not a racer. For me the LEDs are far more economical than the equivalent halogen system.

Reading the thread, I'm not clear on whether you can get a halogen without needing a bottle cage battery. Is there a halogen on the market that will run for 2.5 hours on AA batteries? Is there one that will run for 2.5 on a battery you can strap on to your frame?

Plenty o' halogens out there that run on AA's for 3 hours at a time. Except what wattage are you talking about?

Let's assume 8 AA's give 12V. A 10 watt halogen (which seems to be the standard) at 12V is .83 amps. 8 AA's rated at 2500mah's will give you about 3 hours of run time.

Most battery packs are AA batteries or some variant of them anyway.

Depends on what you define moderate as. A slow pace for me would be about 13-14 mph, which is already beyond what I'm comfortable with in terms of a LED light. A moderate pace at 16-18 would leave me little reaction time. At 20+ I better have some type of halogen or HID lighting.
Then again, in the city, for half my commute, just having the LED blinker is enough, but for the other half through some dark areas of the city and on a high traffic high speed section of road, I like to have more lights.

But he(?) went farther than that, stating that LEDs are "worse headlights" than halogen, period. "More light" for some of us is measured not in lumens, but in hours or days of consistent, reliable light output. No need to have people causing confusion by proclaiming something is "worse" when it isn't. Some of us like our LED lights, and would like to see them succeed so that more models will be developed, reducing prices as well. I've also bought a bunch of parts to hand-build a couple LED lights of my own design, since they're really easy to work with.

The basic choices seem to be:
Lightest and longest battery life: superbright or "luxeon" LED
Cheapest high-output: halogen
Most efficient, highest output: HID
Old-skool dudes: anything running off hub/track generators

Lots of choice for everyone. You might be able to guess that I light my apartment with compact flourescents and 15W light bulbs. I actually much perfer flourescent over incandescent or halogen, which is another kind of lightbulb arguement I get into a lot. My eyes are always dark-adjusted. :)

Man, is it too much to ask that you actually *read* what I wrote? The post is right above yours, for god's sake.

Had you done so, you would see that nowhere do I say that LED are "worse, period". LED produce less light per unit of power at a given time, and less light per unit of money (at least, for quite a while after purchase.) I said that at the outset of my post, and then a couple of sentences later I said they were worse, meaning produce less light, per unit of money or power than halogen. Now you might say the second claim is not exactly the same as the first, since "worse" means something broader than "produce less light", but since I qualified "worse" in terms of units of money and power anyway in the second sentence, you still can't reasonably think that I ever said LED are "worse, period".

Anyway, reading problems aside, the point is just that LED don't produce the same light at a given time as halogen lights if equally powered. They significantly underperform halogen in that respect. They're also more expensive per unit of light than halogen-- at least, for a while after purchase, and as long as we're talking about the presently commercially available LED lights.

When comparing a usable halogen light and an equally powered LED light, the LED will last longer before the battery power fails, true. This is because halogen (and incandescent lights generally) are murder on batteries that drop below their peak voltage. When the battery starts to wane, it goes all the way down very fast after that when powering a halogen light. LED, on the other hand, don't drain weaker batteries so mercilessly, and so get more total life out of the same battery. (The reason is that the filament in an incandescent light has less resistance when it cools, so current flows from the battery much more quickly than when the filament is hotter. With LED, resistance increases as the current level decreases.)

How much does the extended battery life matter? Different amounts to different people. As a practical matter, though, the additional battery life of an LED light is not as much longer than a *comparably powered* halogen light as many people might think. For example, Princeton Tec has a four watt halogen headlamp, the Vortec, that runs on four AA batteries. It'll last 3.5 hours (at 70F). A Cateye Opticube El200 will last between 4-6 hours at the four watt level on four AA batteries.

Of course, like many LED lights, the Cateye permits you to dial down the light and so greatly extend the battery life. The point I'm making now is just that at a comparable power level, the LED don't vastly outlive the halogen competition. I'm not sure many people understand this.

The battery life comparison is important, because operating the halogen light for, say, ten hours is only marginally more expensive in battery cost than operating the LED light for that long. (And there is a lower initial price for the halogen light.) But difference in light output at any given time is in favor of the halogen light by a lot. So, for most people, the halogen still make more sense.

But, yes, people have different preferences. Some people might like the cooler color of LED, they might like the flexibility of light levels available, they might like the light weight of the LED light, they might like the very long run times on low power, or they might have been duped by LED marketing and are too proud to admit it. There are many possibilities. As I said, I've got a Cateye LED, the EL500, because it's very lightweight and because it lasts a long time as a be-seen front light.

For the reasons I mentioned above, though, things might change very soon in favor of commercial LED lights compared to halogen.

With HID, by contrast, matters are different. HID vastly outperform halogen (and LED) in light per unit of power. You get about three times the light per unit of power with HID than with the very best halogen lights, and more than three times compared to more ordinary halogen lights. Since power on bicycles means batteries, and thus significant weight and bulk, there is an easily reached practical upper limit to power on a bicycle. Given that amount of power, HID gives much more light, and perhaps more importantly, HID gives enough more light to move you from the realm of guessing to clear vision and daylight speeds. So, even though HID are more expensive than halogen, total and per lumen, there's a clear reason, for many people, anyway, to spend the money.

I'm not sure what you meant by saying HID are "more efficient". Efficiency needs to be qualified in terms of something you're maximizing, and by your own account other kinds of lights maximize light given money or life given batteries. If you mean what I just said, though, I agree, obviously.