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Brock
Registered Users
Posts:209
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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. - geothermal heated indoor pool with a small solar setup |
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jimdoc
Registered Users
Posts:4
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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
Registered Users
Posts:209
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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. - geothermal heated indoor pool with a small solar setup |
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Jhuanger629
Registered Users
Posts:26
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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
Registered Users
Posts:49
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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
Registered Users
Posts:274
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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
Registered Users
Posts:209
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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. - geothermal heated indoor pool with a small solar setup |
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