Posted on 02/06/2013 11:03:50 AM PST by null and void
Assuming the bulb is on ~20 hrs a week?
22 hours per week, the U.S. Average.
Your mileage may vary. ;-)
I used the same calculator. 40 hours a week comes out to 5.7 hours per day, I put in the national average of $.11 per kilowatt hour. Your cost calculator said that the cost to run a 100 watt light bulb for a year was $20. If you had your 100 watt light bulb running 24 hours a day for a year... the cost would still be only $96.36. What figures did you input?
http://www.citytrf.net/costs_calculator.htm
I am a big fan of LED flash lights, but I don't think that they make good sense yet for interior lighting. But if Comrade Obama gets his way and out rates "necessarily skyrocket" they may pencil out better in the future.
and does the addition of the other P make it a PNP transistor or something like that.
I remeber some thing from basic tr theory at the NATC as Not Pointed in and Pointed in
The problem is not that the LEDs go bad one at a time, but that the Chinese electronics fails and the whole thing goes out.
It looks like one of these Chinese “cottage industry” products. They send out boxes of parts to peasants who hand-assemble them in their own homes. All twisting-wires and snap-together assembly, no soldering.
Hard to believe that mass mechanized production wouldn’t be cheaper, but the people have to have something to do, right? The LED’s are probably made at some factory set up by a Western company and these are just the ones that fell off of the back of the truck.
Changing the cube surfaces from 'white' to 'mirrored' would make a big difference in their 'look'.
Given your assumptions my numbers are in close agreement with yours. I get about 3.8 years.
Given the low end 25,000 hour estimated life, it would last about 22 years.
That would save you about $260 in energy costs assuming the current rates don’t go up.
Given Chinese manufacturing quality? You’d about break even...
I must be missing something somewhere (like brain cells, I'm told!). My kilowatt hour is 10.4 cents. A 100 watt bulb will burn a kilowatt in 10 hours. That's 10.4 cents (+ tax....). 40 hours a week would be 41.6 cents. Times 52 (for a year) would be $21.63. For a regular 100 watt incandescent bulb.
Did I calculate wrong? BTW, 75 watt is the brightest we use, except for porch lights. Normally, it's a 60 watter in each light fixture.
I should have said, “About the end of the fourth year in use”, which is exactly 3.793 years by my calculations. We disagree by 23 hours.
:-)
PNP & NPN are transistors. A single PN junction is a Diode.......
It’s great for applications when you want constant on - 168 hours per week.
It’s great for applications when you want constant on - 168 hours per week.
3.796848188 by mine.
Revised with an 8 hour "day"...it takes $25.40 per year for the 100 watt standard and $3.05 for the 12 watt LED...so we are looking at maybe 2 years rather than 6 months to get your investment back if the LED is around 45 bucks.
You’re living up to the accuracy of your name.
Being Uncle Miltie, my answer is close enough. The decreasing returns to the marginal effort applied to achieve more accuracy are not worth the marginal gains.
:-)
I bought the biggest LED light bulb in Home Depot to try out on my reading lamp. It was hideously expensive and didn’t put near enough light to read by.
Keep trying. Meanwhile, I’m sticking with incandescent.
Emp or brownouts will kill an Led quickly
The payback period is a lot faster than anyone’s suggesting, because no one’s taking into account the heat produced by incandescent bulbs, which requires costly air conditioning to remove.
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