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CocaCola

Apr 7, 2012
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Personally I place about zero validity on stated mcd ratings, and let my eyes in the real world be the judge... I equate mcd to the stated Wattage ratings on Import audio amplifiers, kinda fudged most of the time...

I have personalty seen LM386 amplifier units out of China with 50 Watt rating stickers on them kinda of the same thing ;)
 

Mongrel Shark

Jun 6, 2012
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Those specs are good. 1000 mcd (Milli-candela) = 1 lumen. so 16-20 Lumens per bulb. I think, someone correct me if I'm wrong. Anyway they are bright. Hurt my eyes bright. even with sun glasses on I don't like to look right at them long.

Like Coca-cola say's the straw hat gives 160 degrees. Normally they are a bit pointy, and much lower brightness (in my experience) like 14000mcd. These ones are more rounded, but really low profile, The bit the light comes from is only just under the surface.


The one's I linked to are a little on the blue side. Much like a fluorescent or compact florescent.
If you look at the specs on the page, you will see warm white will only give 13,000 - 16,000 mcd. which is still pretty decent light. I like the full white myself. I know a lot of people prefer the warmer white. I would use warm white in a bedroom, or tv room, but definitely bright white in kitchen/shop/lab. the photon wavelength of pure white light alter brain chemistry, making you more alert and "awake"

Re sticking 1000 individually to the ceiling. Lol! don't do that. you'll get rsi.For 12 v you would be putting them in strings of 3 in series with 83-100 ohm resistor. you can then put them in parallel to form blocks. at 10 ft I'd go for around 30 per bunch, and spread the angle a bit to give more than 160 degrees. Still a lot of soldering, but it's cheap.

Again Coca-cola gives good advice. bigger ones use more power and put out more light. you might also consider something like this They are more expensive, and use 5x the power, but they put out 5x the light as well. so fair trade of, about the same value. a slightly smaller angle is the only downer. Just be careful there. Some 10mm LED's are identical to the 5mm ones inside, just different casing. Could be a trap for beginners.

I'd still go for the 5mm myself, as they would cast less shadows, with there being so many of them. Although if time and risk of rsi are more of a concern, the 8mm every time. the warm white 8mm look pretty decent too. Have a look around and see what you find. I have purchased from that shop a few times. They are ok. Good prices and good quality in my experience. Although postage from China is really slow. 2-4 weeks is fast. sometimes 8-10 weeks.
 

Mongrel Shark

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Bob the trade of in this case could be distance the light is thrown. although they would light a floor or bench well from 10ft. I would go for a narrow beam for a spotlight or some such. they'd be a bit gutless at 50feet or more.. I think the wide angle is messing with your calculator a lot... More like 20 lumans max. I have a LUX meter, if you tell me haw far to measure from I will take a reading for you.
 

BobK

Jan 5, 2010
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Well, the calculator should be correct, IF the luminious intensity is the same over the entire angle, which it most likely is not even close to.

By my thinking, a 160 degree angle is not really desirable for ceiling lighting. A lot of the light would be hitting the upper parts of the walls and not doing you any good. A lot of 60 degree LEDs would be preferable.

Bob
 

CocaCola

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By my thinking, a 160 degree angle is not really desirable for ceiling lighting. A lot of the light would be hitting the upper parts of the walls and not doing you any good. A lot of 60 degree LEDs would be preferable.

That is fully dependent up mounting height and spacing between lights... I used to do graph this out all the time on paper when I would layout a recessed ceiling and/or under the counter light patterns when remodeling kitchens... You want the fills to actually fill the area, especially if it's say a work bench or counter area, best to have overlapping fills than polka dots... When you are aiming for just ambient lighting the wider the spread is generally better...

Consider this, a single light in the middle of a room with a 60 degree spread @ 8 feet height will only light about an 9ish (not exact too lazy to actually work it out) foot in diameter circle on the floor... While a 160 degree spread will light a 90ish (again just a guess, not exact too lazy to actually work it out right now) foot circle... Depending upon you end goal in lighting one or the other might be more desirable for the situation... Now the 90 foot diameter circle is 'overkill' for a work area, but for general illumination you get a lot of fill and bounce that will create a more even light over the entire area, not just a hot spot in the center...
 
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BobK

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Your calculation is a little off: A 160 degree cone at 8ft high will light a 46ft circle. So in a room much smaller than that, most of the light is going to be on the walls, not on your working surface. A 60 degree will light a 4.7 foot circle. So a 2 foot grid of 60 degree lights would work pretty well.

Bob
 

CocaCola

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Your calculation is a little off: A 160 degree cone at 8ft high will light a 46ft circle. So in a room much smaller than that, most of the light is going to be on the walls, not on your working surface. A 60 degree will light a 4.7 foot circle. So a 2 foot grid of 60 degree lights would work pretty well.

Like I said quick guesses on the numbers, more a proof of concept... ** Edit your numbers are correct for radius not diameter ;) My numbers are correct for diameter as I stated... See attached...

In that regard, it really depends upon the application... You assume a 'work' area and in that case I agree, tighter lights and more lights are better... Proof of me agreeing is in my garage that has 150W (equivalent CFLs) on a 3 foot grid over the work areas., pretty much the entire parameter of the garage... Great for a work area but total overkill for just general illumination... First line of lights spaced 18" off the wall the second 54" off the wall... So over a 6' work bench in my garage I have six 150W bulbs illuminating that area, the first row washes down the wall and the second row does a back fill, the end result is nil shadows, hot spots or dull areas on my bench... It works great I love working out there... On the flip side there is only a single 150W bulb dead center in the garage to help fill the main area...

Take my example in the previous post and put a single light in a 10x10 room, with shelves on the parimeter walls... IMO getting the wash down the walls and onto the shelves is far superior than depending on some reflected light off the center of the floor... It's all about the application and desired end goal... And of course the number of lights you willing to grid out, if you have unlimited ability to grid as many as you want, of course tight light gridded tighter is optimal... But, if you have a limited power (wind/solar) source or are looking for the most 'general' illumination for the area, the wider spread becomes an ideal option...
 

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Mongrel Shark

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I'm with Coca Cola on the wide spread. Also. What colour are the walls? If white or a light colour, Then you get reflected light, further washing out shadows. If its a work space as suggested there may be shelves to consider too. You want to be able to see what you got... Although I like to put leds on the bottom of higher shelves too. Provided it's not right at eye level or you have a shield if it is.

The 8mm 120 degree 100ma ones could be a really nice compromise.

I just ran one of the 160 degree leds at low brightness (of my scopes signal gen, 3.7v but low amps for the led). With the low brightness you do see some pretty noticeable short range dissipation. Bear in mind this is about as dim as it goes. I can't read at under a foot. too much reflection, hurts my eyes. from a foot to two feet reading is ideal. after 2 feet I start to squint.by 3 feet from the light its get another light time. This is probably around 10% of the brightness the LED can do. Not happy with that I got some AA's out and did some LUX readings. ! led at 5 feet barely put a lux on my very cheap meter (with 1squre cm sensor) I got 1 lux at 5 feet, couldn't get anything further out (it night time I turned the lights off) With 3 LEDS at 5 feet I got 5 lux and 10 feet I got 1. No worries seeing my way around though. not good for reading past about 8 feet. I also put the 60x equivilent CFL on and the meter on the floor 8 feet (low ceilings) directly under it for a reference reading, 35 lux. At 6 feet its 60. I did some quick rough calculations in my head and the CFL is pretty good on efficiency. Would take around 20 watts to equal it with LED's If you had clusters of 9 (3x3) every meter square it would light up an area very well. As bob says. half the light is directed at the walls. Just depends on your use as to what angle you chose..

The 8mm ones are sounding like the go for this

Re" solar vs wind. With wind if its constant. You would need less battery storage (in amp hours) But wind turbines are pretty expensive watt to watt with solar which is getting down around a dollar a watt. Turbines have moving parts. the need some maintenance. Solar is set and forget. Depends how much light you need when the sun is not out.

For me maintenance, combined with structural requirements of a tower to put the windmill on. makes solar a clear winner every time. If you need light all night and day though. and there is GOOD wind, strong enough to give what you need all the time. or it's cloudy a lot, it would make sense to go that way.

To run the lights we have been discussing. $100 of panel would do pretty well, as long as you have the storage to last out dark and cloudy times. you wont get a windmill with blades and tower/pole etc up under $600 in my very limited experience with wind. Every time I look at wind. Price and maintenance drive me back to solar.
 

Richard Muller

Oct 27, 2012
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I appreciate all the feedback. I should mention the 10ft ceiling height is just where I plan to hang my lights. The roof is pitched and the lowest point is 8ft with the peak being almost 15ft. I will be planning on using the clusters and I really like the 3X3 every 3ft ish. (I know dang Americans and the foot). This lighting is for general lighting. I also plan on focus areas like my work bench where I will need more intense lighting. You guys are great because, there is no way I would know how to calculate any of it without some type of formula and a calculator. I work night shift so most of my work will be done in the shop during the day, but on the weekends I will work late into the night so I really need the best of both worlds. Thank you all so much for such a great discussion. Keep the knowledge flowing.
 

CocaCola

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With the 12-15 foot height you might find the tighter focus to be beneficial, if not a vast majority of the light will be scattered above 'eye' level... With an 8 foot ceiling this in not a big problem since the eyes are give or take 5 to 6 feet when walking, so there is only a little light above the eyes... But at 15 feet the wide spread will cause a lot of the light to simply be lost illuminating the void above you...
 

Richard Muller

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What if I use a deflector like they use in florescent lighting? The lights will not be 15ft above me I will be hanging them at the 10ft level. So roughly 4 ft above my head.
 

CocaCola

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What if I use a deflector like they use in florescent lighting? The lights will not be 15ft above me I will be hanging them at the 10ft level. So roughly 4 ft above my head.

LEDs have built in 'deflectors' that is why they all have angle ratings ;) Unlike other light sources, LEDs by nature produce a directional 'beam' not a 360 degree all around glow like a bulb... A difuser would help spread the light out over a bigger area, but that same effect can be done with a bigger angle LED avoiding the loss in the diffuser...

images
 

Richard Muller

Oct 27, 2012
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ok that makes sense. I am looking at the sticky thread Steve posted about connecting LEDs in an array. Its also great info
 

Mongrel Shark

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Sounds like you want to order up a largish bag of wide angle and a smaller bag of 8mm 120 degrees for you concentrated light areas. a couple down the high point, on a separate switch could be a good idea too. When I had my solar house, I had 12v lighting. with 2 switches on each point. one (big one for fumbling in dark) was just for low power, so you could get around without hurting yourself. watching tv, that sort of stuff. For meal times, reading or making/fixing stuff I had a 12v fluro that was only 20w but looked just like a regular Mains one. So I could have dim light for 1 amp, or bright, daytime light equivalent. for 3 amps draw. Same in the kitchen. Getting a drink. small light. cooking meal big light, and leave it on till dishes done.


As to how to run the lights. Have a look at price per watt for solar vs wind. Then take into account mountings and fixtures, as well as distance of power supply from battery, as the wires have a loss. longer and thinner the wire bigger the loss. Thinker wire over longer distance gets expensive, fast.
If you only need power at night, on some weekends. You probably want a smallish panel. 40-80 watts? and a largish battery or battery bank. Of maybe 100-150 AH. As you will have a week in between big discharges, you can be really nice to the battery and charge it really slow. You will get more in it slowly than fast. Quite a lot more. A few old batterys that Don't start cars on cold mornings would be ideal... Only last 2 years or so. but really cheap. You'll also need a 20-30 amp charge controller. Cheap one's all over ebay from $20-$50 if you want a nice lcd display..
 
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