LED Shop light- questions?

[jav]

I've read most of the posts on these LED shop lights but I still don't understand some things (a lot of things actually).

I understand these lights project more directionally- (not all around like typical fluorescent tubes). Some list a projection angle of something like 120 deg.... which I presume is +/- 60 degrees from vertical but is this only along the long tube axis or is the same +/- 60 degrees projected off the ends as well?

I've also read about flickering/pulsing and noise (audible and electric)... in a non ballasted LED tube- why would there be any of these issues?

I have some LED (array) lights and I do have some individual LED's within the array- that have failed. Most light up- but not all. How likely/common is this on tubes and when would 1, or X number of individual LED failures constitute a warranty replacement..if ever?

 

[mike in tucson]

LED lights are DC, an LED will not operate on AC.....the AC is converted to DC internally for the lamps that run off an AC line. LEDs do not flicker unless the supply is a poorly regulated DC line. Some LED lamps do emit a noise that you can hear. I also suggest that you buy the best available LED stuff....especially not from Lights America. Go to superbrightleds.com for a good comparison....their charts show the output, dimensions and a zillion things. There are some really nice LED stuff out there but there is also the Yugos of the LED lights that are really junk. Just like fluorescent tubes, there are trash ones and good ones.

 

[cybrdyke]

I've read most of the posts on these LED shop lights but I still don't understand some things (a lot of things actually).

I understand these lights project more directionally- (not all around like typical fluorescent tubes). Some list a projection angle of something like 120 deg.... which I presume is +/- 60 degrees from vertical but is this only along the long tube axis or is the same +/- 60 degrees projected off the ends as well?
The "beam angle" of a linear tube is measured longitudinally, like you presumed. There is no reported measurement of the light thrown from the end of tube, although it can show up in photometric charts.
I've also read about flickering/pulsing and noise (audible and electric)... in a non ballasted LED tube- why would there be any of these issues?
Because non-ballasted LED tubes still have ballasts. They're called drivers and they're miniaturized and stuffed into the end of the tube. But they're still there and they still cause problems. This is one of the great myths of ballast bypass tubes...
I have some LED (array) lights and I do have some individual LED's within the array- that have failed. Most light up- but not all. How likely/common is this on tubes and when would 1, or X number of individual LED failures constitute a warranty replacement..if ever?This rarely happens anymore with LED lighting products. But they do lose output over time. Normally, the "lifetime" that is reported to you on the box is the amount of time that it takes the lamp to become only 70% as bright as when it was new. Warranties for LED lamps are nearly impossible to redeem unless the lamp is completely dead before the warranty is over.

Good luck
CD

 

[jav]

Thanks to both of you- especially CD for addressing my points 1 for 1.

so on the beam angle- spacing and orientation do matter within a space since the longitudinal axis will "broadcast" the light a known distance that is height dependant. How do you know the best spacing along the ends if the beam angle only applys along the long axis?


On the driver- I get that an ac-dc conversion, voltage and current limitting need to happen so Mike- thanks - sounds like it's just poor design on the driver circuit? Is there any data to suggest that driver circuits have at least as long a life as the LED's themselves?

Thanks- I presumed as much on the warranty stuff. I was an early adopter of the Cree light bulb and most failed long before incandescents .... of course finding receipts for $10 light bulbs who's life is measured in decades require more forethought than I had.

So in lighting my new shop- I guess I need to ask. Are LED's really the best bang for the buck right now?

 

[cybrdyke]

jav, spacing and calculations is all done by computer these days. The manufacturers supply photometric files and the lighting designers use computers to do their work. DIY-ing it can be difficult. Find someone to do a layout for you. Try wading through the stickies at the top of the lighting sub-forum. You might find one that is near the same size as your space.
The driver is the weak link in any LED system. It's the most prone to heat, voltage spikes, over-current, etc. It will not typically last as long as the LEDs themselves.
LEDs and T8s are very close in bang for buck.
Good luck
CD