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5 Watt LED lamps.
Has anyone tried out the 5 Watt LEDs?
I've just ordered one and I'm wondering how other people set theirs up. What battery arrangement do you have and how long do they last? What lens angle do you have, (if you use a lens?) Do you do road or MTB and is 5 Watts enough for technical MTB? Is it handlebar or helmet mounted? Do you have a multiple LED setup? Marty |
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#2
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5 Watt LED lamps.
Marty Wallace wrote:
Has anyone tried out the 5 Watt LEDs? I've just ordered one and I'm wondering how other people set theirs up. What battery arrangement do you have and how long do they last? What lens angle do you have, (if you use a lens?) Do you do road or MTB and is 5 Watts enough for technical MTB? Is it handlebar or helmet mounted? Do you have a multiple LED setup? I had seriously considered LEDs as a replacement to halogens when I was last replacing the lights on my bike. After looking at the pros and cons, I opted to stay with halogens. -As far as efficiency goes, the 5W luxeon leds are about as good as the best of the halogens, if not better. -The leds need heatsinking, halogens don't. (more space, possibly more weight). -Halogens can be run directly off the battery (6 or 12v depending on the bulbs), where the leds need a dedicated power supply. (extra cost). -The white 5W luxeon leds have a quoted life of about 500 hours (to half brightness if I recall correctly), your typical halogen is about 2000 hours (till it burns out) -Dollar for dollar, haloges are a LOT cheaper than the LEDs. -If you're trying to extend life, LEDs are killed by heat, so the better heatsinking you can apply to the led, the better. Halogens are killed by overvoltage (even a bit), so the closer to the rated voltage you can supply them, the better. On an interesting but unrelated note, if you undervoltage halogens far enough, their efficiency drops to something really shocking (forget about battery power), and their life expectancy drops significantly too. (that's why dimmers on home downlights is a stupid idea). After all that, you can see why I stuck to halogens. -- Linux Registered User # 302622 http://counter.li.org |
#3
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5 Watt LED lamps.
On an interesting but unrelated note, if you undervoltage halogens far enough, their efficiency drops to something really shocking (forget about battery power), and their life expectancy drops significantly too. (that's why dimmers on home downlights is a stupid idea). After all that, you can see why I stuck to halogens. -- Linux Registered User # 302622 http://counter.li.org I sort of suspected as much. I often wondered if there was much point to a dimmer. A second lower wattage bulb would probably be more efficient. Marty |
#4
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5 Watt LED lamps.
Marty Wallace wrote:
I sort of suspected as much. I often wondered if there was much point to a dimmer. A second lower wattage bulb would probably be more efficient. And offer a whiter light. -- Linux Registered User # 302622 http://counter.li.org |
#5
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5 Watt LED lamps.
"John Tserkezis" wrote in message u... Marty Wallace wrote: Halogens are killed by overvoltage (even a bit), so the closer to the rated voltage you can supply them, the better. Not entirely true.......you can overvolt halogens with out too many problems as long as you have a circuit to provide a "soft startup" where you gradually increase the voltage to the final voltage. This reduces the stress to the globe caused by going from zero to full voltage in a single step (ever notice how globes usually blow when you first turn them on?). The advantage of overvolting halogens is that you get more light intensity than the extra power you are pumping in (ie the halogens run more efficiently). This is more bang for your buck as if your increase in voltage results in a 10% increase in the power that the lamp is using, you will get a corresponding increase of greater than 10% in the intensity of the light. I have run my 12V halogens using 11 NiMh cells (13.2V nominal) without any problems thus far.....I am sure that I can remember reading a web site that reckons that you can even add a 12th cell for 14.4V without too much drama. You may reduce the total life of the globe from thousands of hours to hundreds of hours but this is still a lot of night riding time. Cheers, Gags |
#6
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5 Watt LED lamps.
Gags wrote:
Not entirely true.......you can overvolt halogens with out too many problems as long as you have a circuit to provide a "soft startup" where you gradually increase the voltage to the final voltage. This reduces the stress to the globe caused by going from zero to full voltage in a single step (ever notice how globes usually blow when you first turn them on?). Bzzzt. Turn-on surge is more a problem with mains operated incadescent bulbs, where the filament is quite thin and fragile. The turn-on surge, something like 10 times normal operating current, shakes the filament to bits if it's already weak. Low voltage halogens have quite thick and rugged filaments, so don't suffer from this problem. And they DO have a shorter life when run above their rated voltage. The advantage of overvolting halogens is that you get more light intensity than the extra power you are pumping in (ie the halogens run more efficiently). This is more bang for your buck as if your increase in voltage results in a 10% increase in the power that the lamp is using, you will get a corresponding increase of greater than 10% in the intensity of the light. It's a heck of a lot more than just "greater than 10%". With heck of a reduction in operating life as well. I have run my 12V halogens using 11 NiMh cells (13.2V nominal) without any problems thus far.....I am sure that I can remember reading a web site that reckons that you can even add a 12th cell for 14.4V without too much drama. You may reduce the total life of the globe from thousands of hours to hundreds of hours but this is still a lot of night riding time. As long as you can acknowledge there is a significant reduction in life. Operating life might not be an important issue to you, but we don't know that everyone else might not care about life. -- Linux Registered User # 302622 http://counter.li.org |
#7
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5 Watt LED lamps.
On Sun, 21 Mar 2004 00:34:12 +1100, John Tserkezis
wrote: The advantage of overvolting halogens is that you get more light intensity than the extra power you are pumping in (ie the halogens run more efficiently). This is more bang for your buck as if your increase in voltage results in a 10% increase in the power that the lamp is using, you will get a corresponding increase of greater than 10% in the intensity of the light. It's a heck of a lot more than just "greater than 10%". With heck of a reduction in operating life as well. I have run my 12V halogens using 11 NiMh cells (13.2V nominal) without any problems thus far.....I am sure that I can remember reading a web site that reckons that you can even add a 12th cell for 14.4V without too much drama. You may reduce the total life of the globe from thousands of hours to hundreds of hours but this is still a lot of night riding time. As long as you can acknowledge there is a significant reduction in life. Operating life might not be an important issue to you, but we don't know that everyone else might not care about life. Here's an example of a manufacturer that deliberately over-voltages. They claim 38% greater light output with a 15% increase in power consumption. Their bulbs should last around 1000 hours, instead of "several thousand hours" if they weren't over-voltaged. Seemed like a good equation to me. I can't comment on the actual lifespan yet, since I've only had the light for a month or so... Probably a good idea to use two lights instead of one, for when one does die. http://www.lumicycle.co.uk/over.html |
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