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Brock
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Posts:431
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| 08/01/2008 2:40 PM |
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You can get what is called a balancer, which will take some power from the other 4 volt cells and put it in the one that is the lowest, although they are not cheap. Honestly I would just get an LED that could accept 12v directly, either resistored down or 3 in series or even a 12v switching supply to down convert it to keep the batteries balanced.
If you do happen to draw one down below the rest getting them balanced again without a balancer will be difficult and if they don’t remain balanced they will tend to have a shorter life span because the more used cell will tend to be undercharged and the less used cell will tend to be overcharged.
I have had good luck with this online store
http://www.ledwholesalers.com/store/
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Green Bay, WI. - 4 ton horizontal, 16k gallon indoor pool, 1.8kw solar PV setup, 3400 sq ft |
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jimdoc
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| 08/08/2008 5:27 PM |
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When I looked into this a year or so back, it seemed that CFL's and LED's were roughly equivalent in terms of lumens per watt. In other words, they both turn electricity into light equally well. However, CFL's are unlikely to get much better than they are now (we have been making fluorescent lighting for a LONG time), while LED's are near the start of their development curve.
Calculated in unit cost (not electricity cost) per lumen, LED's are much more expensive at present, but calculated in unit cost per lumen-year (or lumen-hour), I thnk LED's are already cheaper, since they are likely to last many times longer than CFL's.
Further, CFL's have mercury in them, and can break; LED's do not, and can't.
If you are building from scratch, my idea is to look into mostly cove-style lighting with strips of LED's, and aimable LED spots, rather than trying to be retro and utilize screw-in LED "bulbs". And look into doing it all with a low-voltage system....
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Brock
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| 08/09/2008 12:07 AM |
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Another big advantage for LED's is starting in cold weather, they don’t care how cold it is, actually they get a bit more efficient as they get colder. So for outside lights that get flipped on and off LED's are the way to go. A CF would almost have to be left on, or turned on for 5 minutes to reach full brightness, if it even can when it's really cold out.
And I would agree with Jim. I have seen some amazing LED chips lately, some in the 100w range on a singe die approaching and some at 100 lumens per watt or about 2 to 3 times what they are now. Again as Jim noted, LED are still really being developed and have room for improvement, where CF's are towards the end of their development. |
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Green Bay, WI. - 4 ton horizontal, 16k gallon indoor pool, 1.8kw solar PV setup, 3400 sq ft |
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Jhuanger629
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Posts:31
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| 09/02/2008 5:03 PM |
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| A friend and colleague of mine runs an "environmental" lighting store specializing in LED interior lighting. If any of you are interested, I can put you in contact directly (no incentive on my part other than paying it forward) and hopefully impart a slight discount? |
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Vermonter
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Posts:52
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| 09/02/2008 6:26 PM |
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| Does this store have a website? Do they offer the new Cree or Seoul LEDs? |
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Jelly
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Posts:486
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| 09/11/2008 12:56 PM |
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I bought a battery operated LED light recently during the week-long power outage from the hurricane. There was a big sticker on it that read "LED RADIATION, DO NOT STARE AT BULB"
What's that about? It's too bright to stare at anyway, but I've got a curious kid that might give it a try. |
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Brock
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Posts:431
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| 09/11/2008 4:31 PM |
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Basically LED's emit light in spikes on the light spectrum. So your eyes won't adjust down to protect themselves from the light. Sort of like looking at an eclipse, lots of UV and IR but not as much visible light so your eyes don't adjust down for it. As long as you don't stare at them or look directly at them for any length of time your fine. A flash across the eyes shouldn't hurt anything.
Having said that I don't let my kids play with my brighter LED lights, then again I have a couple 10w and a 20w lights, they get the 1watt and less lights and if they shine each other in the face they are taken away. |
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Green Bay, WI. - 4 ton horizontal, 16k gallon indoor pool, 1.8kw solar PV setup, 3400 sq ft |
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MarkosWoodWorking
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Posts:36
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| 12/24/2008 3:27 PM |
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| Brock makes and excellent point about cold weather and CFL's. If you've every tried to start up any Flourescent light in mildly cold weather (or worse) you know exactly what's going on there. In fact, I'd have to say LED would be my first choice for outdoor lighting, unless really good flood lighting is important...in that case, I'd use a mercury vapor light, which unfortunately is not at all energy efficient. |
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Matthew Sokalski
Markos WoodWorking,
Akasu Contracting and Consulting (Attr.) |
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Vermonter
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TechGromit
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| 01/28/2009 11:45 AM |
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Posted By cmkavala on 10/27/2007 9:47 AM
The quality is fantastic, they can hit any color shade and they are dim-able and projected to last 50 years
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cmkavala
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Posts:1384
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| 01/28/2009 12:37 PM |
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Posted By TechGromit on 01/28/2009 11:45 AM
Posted By cmkavala on 10/27/2007 9:47 AM
The quality is fantastic, they can hit any color shade and they are dim-able and projected to last 50 years
50 years? Where are you getting these figures from. From what I read so far, 50,000 hours is LED life expentancy. Although I would imagine they can last longer, like solar panels where there life span is estimated at 25 years, but can continue to last for dacades after that, but with decrease output.
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Chris Kavala
chris@southernsips dot com
1-877-321-SIPS |
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Brock
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Posts:431
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| 01/28/2009 12:49 PM |
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The life of LED's is misleading; typically they are rated for 100,000 hours IF they are run at rated wattages with the heat sink they want. Typically I am seeing LED's pushed way beyond their rated wattages with some heat sinking, not what is recommended and typically they group the LED's so there is no way they can rid themselves of the excess heat.
If you run a LED with adequate cooling and below rated wattages I would imagine they would easily run 100,000 hours or much much longer, but it seems very few manufactures do this. And even if you heat sink the LED if it is a standard base lamp and you mount it in the ceiling in a can, most of the heat will all stay right there anyway.
I am afraid LED’s will get the same bad rap as early CF's and many other new technologies get when some manufactures take advantage of a new market.
I know from personal experience of two manufactures making almost identical traffic lights, I know one of them is using good heat sinking and moving the power supply’s off the boards, while the other is pushing the LED’s to almost twice their rated wattage and has poor heat sinking. The cost was about 1/2 for the cheaper one, guess which one will run 10 years without any problems... Yet LED's will get a bad name because of implementation like this. |
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Green Bay, WI. - 4 ton horizontal, 16k gallon indoor pool, 1.8kw solar PV setup, 3400 sq ft |
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cmkavala
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| 01/28/2009 1:15 PM |
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Brock;
regardless of 25 or 50 years they will be much better than CFs, I have my entire house outfitted with CF,s and a couple LEDs (but at $30. a pop to rich for me)
I am very disapointed wth CF's their claim is 7 years, but I am replacing some every 6 months. |
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Chris Kavala
chris@southernsips dot com
1-877-321-SIPS |
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Brock
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Posts:431
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| 01/28/2009 3:23 PM |
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| For sure, I have a few LED’s scattered about. They are nice for motion sensors in the garage where it's colder, they come on to full brightness (all be it dim at 25w equivalent). I know I burn out more CF's compared to when we used to have incan's everywhere. But I can't complain since the cost has come down and they use 1/4 the wattage... Some of my CF's are really nice and have lasted a long time (to long, they are the ugly old tube style) and some die a quick death (a year or less). Honestly I think this is the same sort of situation where some are made to last and some are made to be cheap and disposable. I just have to stick with the better brands and quit trying to save a buck when I am buying them. |
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Green Bay, WI. - 4 ton horizontal, 16k gallon indoor pool, 1.8kw solar PV setup, 3400 sq ft |
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Brock
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| 01/28/2009 3:29 PM |
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Oh the other place I use LED’s is for night lights in the kids room and kids bathroom, cool to the touch and use about 1/4 watt for about 4 watts of light. I also have some on our stairways that just stay on all the time and at night they are more than enough to see the stairs without flipping on the blinding 18w CF :)
We have two incandescent lights in our house in the stove and microwave. I tried swapping them to LED, all I can say is don't try it, LED can melt ;) Otherwise it’s mostly CF’s with a few LED’s thrown in. Oh we have a tray ceiling in our living room and bedroom; both have white defuse Christmas LED stings in them. They pull about 10 watts each and really light the room up evenly. My wife actually made me put a dimmer on the ones in our room, which sort of works. |
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Green Bay, WI. - 4 ton horizontal, 16k gallon indoor pool, 1.8kw solar PV setup, 3400 sq ft |
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Summers
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| 01/30/2009 9:02 PM |
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Chris,
You opened up a can of worms when you started this. Your original request was for"Affordable"!
After having read some of the comments, I'll share this with you. Just finished a install of Led's, using a bunch of 4"and 6" cans. Took forever to sift thru the maze of information, some good, some bad. One of the links mentioned in this topic, was a contender for a while. I was looking at remote dimmers for one room and my question to the sales type was, "OK, I'm buying 12 of these units, does each one come with it's own transmitter[car key chain size] for dimming control and if so can I use just one for all lights in this room?" He didn't know but realized, that would be a problem if I had to dim each light indivdually, using a different remote. DUHHH
My choice of sites came down to www.ledhomeplace.com and www.cree.com for Real Information. Finally bought from Cree through City Electric Supply. Used conventional wiring (no Humming rectifiers) and am very happy!
Great lighting, also saves on A/C with reduced heat load if your in a warm climate.
Affordable? They weren't cheap,but they are quality that will be here for a long time. If you watch the Super Bowl from Raymond James Stadium, look at the light quality there. Complete changeover to LED
Glenn |
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The Cost Effective Answer to Concrete Corrosion |
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cmkavala
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Posts:1384
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| 01/31/2009 8:36 AM |
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Glenn;
thanks..I am a Bucs season ticket holder how long ago was the change over
I know they are not affordable yet, like CFLs wern't in the begining, but my hope is that they will come down in 2 years when I do my next personal build
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Chris Kavala
chris@southernsips dot com
1-877-321-SIPS |
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SimonD
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zircote
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Posts:40
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| 02/03/2009 10:07 AM |
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The life time of LEDs like solar panels can be very long.
Most manufactures state a 50K hour life.
This means with proper heat sinking and current drive the LED will produce light within it's specified output range for 50K hours.
After 50K hours the LED will still produce light just not enough to meet the original spec.
If the LED is run at a lower current and uses a better heat sink it will certainly last much longer. However, the LED will not be producing the rated output spec'ed by the manufacture.
In many cases derating, lower current drive, the LED is not noticeable to the end user.
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zircote
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Posts:40
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| 02/03/2009 10:15 AM |
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Oh, forgot to mention.
All of the major manufactures of CFLs own LED designs and manufacturing facilities.
Phillips own Lumiled for example.
My personal opinion is the CFL plants have yet to pay for themselves and until then the price of high power LEDs will remain high. The CFL plants are not very old, but once they have been depreciated sufficiently then the change over will begin in earnest.
Properly designed LEDs are the real energy saver not CFLs.
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