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DanDMan

metal-halide, branded.

Dont forget to factor in the cost of the bulbs also.

Quote:

Metal Halide and LED Life Span a 20,000 hour life, according to the manufacturer's data sheets. Improper bulb orientation can actually reduce the life by 5,000 hours. Near the end of life, the bulb will begin to exhibit "cycling". As the lamp ages, the required voltage increases beyond the available source voltage. With increasing internal temperature, the lamp will fail. After a brief cooling period, the lamp will re-start. This process will then repeat on a continuing basis. Aging LED lights do not exhibit similar behavior! An LED fixture designed to replace metal halides in gas station canopies, can provide up to, or in excess of 50,000 hours of life. The LED lights may remain operational for as long as 100,000 hours, at a decreased luminous output.

Quote:

LED Beam Angle

Due to the directional characteristics of traditional metal halides, the bulb produces mass amounts of wasted light from the top and sides of the lens. This result in a lower system efficiency. However, LED lights feature superior directional characteristics, and can dramatically reduce night sky pollution. The narrow beam angle featured on many LED lights provides illumination within the intended areas only. Not only does this reduce light pollution, but also promotes higher overall system efficiency.

steve

i like the coralife one

6000K is still quite warm, 7500k would have less oranges and yellows

just on that first quote dan, the gas station example is not valid as we're now talking about white light for illumination not targeted wavelengths for plants.

hence a white light led array to replace a MH fixture at a gas station is going to be about 50% as efficient as the MH. The MH's also have mirrored reflectors in their fixtures, and i think the off cycling is a good thing.

why? becasue it forces the owner to replace the bloody things.

the LEDs will run to 100,000 hours but at about 50% efficiency output per watt, so now we're down to 25% of a non cycling MH.

point as made about improper bulb orientation (unlikely if you buy the right bulb for the fixture reducing life hours, but no mention of drastically reduced led life at powers between 70% and 100% and at elevated junction temperatures.

two sides to every story.

dont get me wrong, i love LED's and they've gone great guns since they were first made. I sincerely hope that they soo reach the point that a discussion of merits VS MH is a moot point.

I will say though that for low to medium power ie below the MH minimum threshold, the LED trump anything else on the market.

I recently bought a 3W LED dive torch, better color, penetration, bulb life and battery life. what more could i ask for? (a MH dive light LOL

)

swanberg

For future forum browsers, my basement barrelponics setup, http://backyardaquaponics.com/forum/viewtopic.php?t=3047
will be using LED growlights. The system isn't up yet, but should be soon.

DanDMan

A Super-Efficient Light Bulb
A Silicon Valley company, Luxim, that has developed a tiny, full-spectrum light bulb, based on a plasma of argon gas, that gives off as much light as a streetlight while using less power. The Tic Tac-sized bulb operates at temperatures up to 6000K and produces 140 lumens/watt, almost ten times as efficient as standard incandescent lamps, and twice the efficiency of high-end LEDs. The new bulbs also have a lifetime of 20,000 hours. There's no mention of mercury or other heavy metals, which pose a problem for compact fluorescents.

Read the Story Here

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