#### strantor

Joined Oct 3, 2010
5,333
A year or two ago there was a big hullabaloo about CFLs. Everyone was up in arms about the .gov and mercury and whatnot. Big brawl about it here and on ETO IIRC.

Well, I think they may be already obsolete (or quickly becoming so), thanks to LEDs. I crunched the numbers because I have these 150W halogen security flood lights outside my house and the switch is in the back of my detached garage. The motion sensors that control them are stuck ON and I have to go inside the garage every morning and turn the switch off, which I never remember to do, so they stay on almost 24/7.

I know, I should just fix the damned things, but I only think of it at times like now, when I don't have the opportunity. Since I'm away from the house now and can't fix it, I decided instead to do some math for a 24/7 ON light, comparing incandescent to LED to CFL, and here are the results:

As you can see, what I'm paying for my current security lights ($199 X 4) is outrageous! LED and CFL come in neck and neck on price, but the LED is twice as bright. I'm considering upgrading all my lights (even my car headlights) to LED, despite the momentary sting of upfront high cost. #### StayatHomeElectronics Joined Sep 25, 2008 1,070 I have changed a bunch of lights throughout my house to LED bulbs, especially the ones that my wife and kids leave on all day. While it has made an impact on the electric bill, the largest side benefit is that I am not always going around the house changing light bulbs. I have only changed two or three light bulbs in the last year. One was a CFL in a fan that lasted at least 4 years, can't really complain about that. The other was an incandescent bulb in a bathroom fixture where the bulb is exposed. I have yet to find a really nice looking LED to put in there. I have had luck with the LED bulbs I have installed so far. None have died, yet. #### joeyd999 Joined Jun 6, 2011 4,429 Only 39,967 hours life for the LED bulb? I refuse -- until they make one with 40,000 hours life. #### GopherT Joined Nov 23, 2012 8,012 A year or two ago there was a big hullabaloo about CFLs. Everyone was up in arms about the .gov and mercury and whatnot. Big brawl about it here and on ETO IIRC. Well, I think they may be already obsolete (or quickly becoming so), thanks to LEDs. I crunched the numbers because I have these 150W halogen security flood lights outside my house and the switch is in the back of my detached garage. The motion sensors that control them are stuck ON and I have to go inside the garage every morning and turn the switch off, which I never remember to do, so they stay on almost 24/7. I know, I should just fix the damned things, but I only think of it at times like now, when I don't have the opportunity. Since I'm away from the house now and can't fix it, I decided instead to do some math for a 24/7 ON light, comparing incandescent to LED to CFL, and here are the results: View attachment 93181 As you can see, what I'm paying for my current security lights ($199 X 4) is outrageous! LED and CFL come in neck and neck on price, but the LED is twice as bright.

I'm considering upgrading all my lights (even my car headlights) to LED, despite the momentary sting of upfront high cost.
There is a bit of foolishness about the LED lifetime. Since high brightness LEDs have not been around so long, the lifetime is determined by accelerated aging tests (of the LED). There is no accelerated aging test of the components in the power supply, the contacts or the heat sink coatings/interface. High wattage LED bulbs run relatively hot for electronics, especially if in recessed can lights. I used to praise the benefits of LEDs as 30 years, then my friends and family started to complain. 2 years, 3 years, 4 years of life and they are dead in some cases. I've opened them up to see discoloration on the PCB, and popped capacitors. Designs are getting better all the time. Even those produced 3 and 4 years ago were not so efficient. As the lumens/watt goes up, the heat left over goes down (for equivalent light output). All I'm saying is, be careful with your assumptions. Also, check how much brightness is left in a 30-year-0ld LED. I think they say 50% for the test.

Also, you have to balance the environmental issues of mercury in the CFL vs. the mining and refining and purification effort that goes on in producing the gallium chloride and, finally, trimethylgallium needed for the GaN LED. It is a long process for 99.99999% purity gallium. Worse for the small amount of indium component but that is much smaller volume and rarely mentioned.

#### sirch2

Joined Jan 21, 2013
1,026
I have incandescent bulbs in the house that have outlasted both CFLs and LEDs. The CFLs generally don't fail but take so long to warm up that they have to be replaced, the LEDs just fail, I guess it may be the drive circuit rather than the actual LEDs that fails but they still have to be replaced, some after only a year or so. The whole life cost of incandescents looks pretty good to me.

#### strantor

Joined Oct 3, 2010
5,333
There is a bit of foolishness about the LED lifetime. [...] I used to praise the benefits of LEDs as 30 years, then my friends and family started to complain. 2 years, 3 years, 4 years of life and they are dead in some cases. I've opened them up to see discoloration on the PCB, and popped capacitors.
Yes, I did consider this. I think the numbers I posted are likely close to valid, considering I assumed a 24/7 ON time, and a life span measured in hours, not years. For the LED (and the other two), I took the manufacturer's provided garbage:

...and turned it into hours : ((3/24)hrs*36.5yrs) = 4.5625yrs = 39,967hrs

4.5 years of continuous ON time does not seem entirely unreasonable to me; 36.5 years of intermittent usage, does.

Even if 4.5 years is unobtainable, or even if you don't keep the light on enough hours per day to get all the benefit of the longer ON lifespan, they still beat incandescent hands down based on power consumption. CFL is a closer call. But I have experience with CFL and my experience says CFLs will pop early and sometimes with quite a brilliant show (of flames and sparks). If LED has similar performance, maybe CFL is still the winner. I don't know, not enough data for me to call it. ... well, unless you consider the LED is 2X as bright, maybe that tips the scales in its favor.

#### ronv

Joined Nov 12, 2008
3,770
A year or two ago there was a big hullabaloo about CFLs. Everyone was up in arms about the .gov and mercury and whatnot. Big brawl about it here and on ETO IIRC.

Well, I think they may be already obsolete (or quickly becoming so), thanks to LEDs. I crunched the numbers because I have these 150W halogen security flood lights outside my house and the switch is in the back of my detached garage. The motion sensors that control them are stuck ON and I have to go inside the garage every morning and turn the switch off, which I never remember to do, so they stay on almost 24/7.

I know, I should just fix the damned things, but I only think of it at times like now, when I don't have the opportunity. Since I'm away from the house now and can't fix it, I decided instead to do some math for a 24/7 ON light, comparing incandescent to LED to CFL, and here are the results:
View attachment 93181