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Author Topic: Led light replacement of a 300wat halogen  (Read 2409 times)
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At home i have a 300 watt halogen lamp, to light-up my room.
I am thinking of replacing it with something based on power Leds, probably several of them an i dont know how many would be required.

I want this to become more energy efficient, and maybe combine it with an AtTiny so i could co handclap control, or combine it with an outside light sensor.
But as an energy efficient lamp, i think it should work straight on 220V (instead of my 9v arduino projects), but i dont know much about a good scheme to make it.
I've seen some Led schemes that worked with limited led power, but not for power leds and not arduino.
I know there are various ways to go down from 220v to somethng else, i just dont know what is energy efficient and what is not.

(a background thought here, replacing this lamp would be better then putting a solar panel on my roof)
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Fort Lauderdale, FL
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You need a high power LED driver.  These are constant-current power supplies specifically designed to provide large amounts of constant current.  They are far more efficient than using a simple resistor, for example.  There are drivers designed to work directly off of mains. 

Try starting your search with "220v led driver".
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I've seen a 5W mains LED array, but nothing higher power.   There are 25W, 50W and 100W led arrays available,
all require a particular DC voltage/current (for instance the 100W arrays are 10 strings of 10, so about 32V at 3.15A...)

Yes a constant-current driver is needed for such DC LED arrays.  And plenty of heatsinking / fan.

Checkout dx.com for examples of these LED arrays - search "100W LED" or whatever.
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if a heatsync is required then how can such a solution be energy efficient ?
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I know there are various ways to go down from 220v to somethng else, i just dont know what is energy efficient and what is not.
Any "LED power supply" for high-power LEDs will be a switching design that's nearly 100% efficient.  With a switching power supply (under normal operating conditions), you get more current out than you put in (at less voltage).

So you can probably ignore the power loss in teh power supply and just look at the power consumption and light output of the LED(s).  You could subtract 1 or 2 percent for power supply efficiency, but the specs might have that much normal variation anyway.

You can get screw-in LED lamps that have built-in power supplies and run off regular household power (example).   If you just want to turn it on/off automatically, you can do that with a relay (or solid state relay) just like any other AC lamp. Some are dimmable (with a regular AC dimmer), and some are not.

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At home i have a 300 watt halogen lamp, to light-up my room.
I looked-up the light-output for a 300W halogen.   The 1st one I found is about 6000 lumens.     LEDs that put-out that much are very expensive!    I found some floodlight-style 20W LED lamps that put-out 1000 lumens for around $40 USD.  Based on that, I'd guess you are going to need roughly 120W of total LED power.  If those numbers are correct (and you should probably double-check smiley-wink, you'd be reducing you renergy consumption by about 60%.
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One 300 Watt halogen lamp
Life: 2,000 hours
Initial Lumens: 5,950 lumens

One A21 LED 22W
Life: 25,000 hours
Initial Lumens: 1,780 lumens

You need 3 pcs A21 LED 22W  in total 66W to replace One 300 Watt halogen lamp.





A21-22-Watt form homedepot, $54.97

More Information from geek.com
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if a heatsync is required then how can such a solution be energy efficient ?
LEDs are not 100% effecient, and high power LEDs need heatsinks.

In the winter, the heat produced by the lightbulb (of any type) reduces the heat required by your furnace, so it's not wasted.   But, electric heat is often more expensive than gas, oil, or coal.   In the summer, if you have air conditioning, you are paying for the wasted heat plus more energy to get rid of that heat!
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Something like this, maybe?

http://www.ebay.ca/itm/Flood-LED-Light-120V-50W-Wash-Bulb-Lamp-Day-Light-Waterproof-LEF120V50DL-1P-/150966937971?pt=LH_DefaultDomain_0&hash=item232654a973
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if a heatsync is required then how can such a solution be energy efficient ?
It's more efficient than the existing lighting solutions.
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We need treat LED as food from supermarket, the fresher, the better.

Haitz’s Law
Consider Haitz’s law as the LED equivalent of Moore’s law, Haitz Law states that: Every decade, the cost per lumen (unit of useful light emitted) falls by a factor of 10, the amount of light generated per LED package increases by a factor of 20.



The newer LED will have higher efficiency.  

22W LED 1,780 lumens is right, 20W LED 1,000 lumens is OK, It could be only difference of production date ( say 8 months).

Philips 22-Watt (100W) A21 LED releases at 2012/12, plus it is dimmable.  It is the way to to go?

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While those Philips light are nice, they are expensive.  $150 to replace a $5 bulb.  I know this is not really green thinking, but here electricity is about $0.09 per kWh, so it would take (150/0.09)*(1000/(300-66)) = 7122 continuous hours of running those Philips bulbs before they even begin to pay off.  If we assume an average of 4 hours of usage each day, that's more than 4.5 years before a return on investment is realized.

Now that I've done the math, there may be some merit to this as long as the LED bulbs last as long as promised.  Something that has never been delivered with the CFL bulbs.  They last only about 1/4 as long as they are advertised to.
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That is Haitz’s Law told us;-  the cost per lumen (unit of useful light emitted) falls by a factor of 10, we need give time to allow it fall.

Meanwhile there are 2 major factors to control consumer product's price;-

1. mass productions
2. bloody competition

OK, could be third one "made in China".

Philips 22-Watt (100W) A21 LED is new, might not meet any of above factors. We might need wait one  year to revisit this.
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While those Philips light are nice, they are expensive.  $150 to replace a $5 bulb.  I know this is not really green thinking, but here electricity is about $0.09 per kWh, so it would take (150/0.09)*(1000/(300-66)) = 7122 continuous hours of running those Philips bulbs before they even begin to pay off.  If we assume an average of 4 hours of usage each day, that's more than 4.5 years before a return on investment is realized.

Now that I've done the math, there may be some merit to this as long as the LED bulbs last as long as promised.  Something that has never been delivered with the CFL bulbs.  They last only about 1/4 as long as they are advertised to.

$0.09 per kWh, That is a great, could you tell us the city name you live? I will move to it.

The prices at place I live.
Electricity prices average of 20.2 cents per kilowatt hour (kWh).
Gasoline prices averaged $3.692 a gallon.
The average cost of utility (piped) gas at $1.241 per therm.
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Sorry to continue the hijack.  I just ordered two LED bulbs from the far east as possible replacements for CFL type bulbs since, as BillO pointed out, they don't last long, especially when installed base up.  They are in the 10W/1000 lumen range and intended to replace the typical 18W CFL.  One is a corn-cob type (~$6) the other is a globe type (~$10).  If they work out (and that is by no means a foregone conclusion) they would be worth the cost.  We'll have to see.
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$150 to replace a $5 bulb

This is not apple to apple compare. correct one should be $150 to replace a 12.5*$5 bulb, i.e $150 to replace a $62 bulb.
I agree with BillO about misleading advertisements. but for Philips v.s. no brand name from Ebay, I will trust Philips more.

Other thread about misleading advertisements;-
http://arduino.cc/forum/index.php/topic,163818.msg1225604.html#msg1225604




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