What is with LED light efficiency?

[Rifter]

Whats really bad about LED's is CRI, some can be as low as 50-60, and you really want a CRI of over 90 for real looking colors and only the top tier and top binned LED's can provide that making it hard to buy bulbs with a CRI over 90.

 

[Imp]

Now I'm kinda curious if my flashlight does indeed use PWM or if it just uses a dropper resistor. Suppose one way to find out is to hook up a solar panel to my scope. Can sometimes see PWM with naked eye but really depends on the frequency. I can see projector PWM sometimes, well that's not really PWM just line scanning.

There's some guy on YouTube who opens up LED bulbs and then checks to see if they flicker using a device. I want to say oscilloscope but I don't think that's it.

 

[Herr Kutz]

Anybody know if the Walmart LED's are any good?

I've been using the 60W versions in all the fixtures I can reach in my rental since last July and have had no issues thus far. I only wish I had 100W equivalent versions in my middle room, but the local Wally World sells a 4 pack of the 60W versions for $1.98+tax so I stuck with them.

 

[DCal430]

Whats really bad about LED's is CRI, some can be as low as 50-60, and you really want a CRI of over 90 for real looking colors and only the top tier and top binned LED's can provide that making it hard to buy bulbs with a CRI over 90.

The problem with bulbs with a CRI of over 90 is nearly all have very poor efficiency. Most are under 70lm/watt and many are barely over 50.

Is a bulb that is 84CRI and 120lm/watt really worst than one that is 94CRI and only 65lm/watt. The higher CRI consume almost twice as much electricity.

 

[stormkroe]

Basic design guideline for an LED is, the brighter it is, the less efficient it gets. That's why efficiency costs more, because they can drive the same total lumens with less wattage by simply adding more LEDS inside the bulb.

 

[Rifter]

The problem with bulbs with a CRI of over 90 is nearly all have very poor efficiency. Most are under 70lm/watt and many are barely over 50.

Is a bulb that is 84CRI and 120lm/watt really worst than one that is 94CRI and only 65lm/watt. The higher CRI consume almost twice as much electricity.

Yeah its a balance for sure, i think CRI of 80-90 is probably ok for general use but you are going to want highest CRI possible for bathroom, make up area's , closets, etc. where real colors matter.

When i converted my apartment to LED a few years ago it was my girlfriend that complained about colors looking off in her make up area she uses to get ready in the mornings and thats when i started looking into CRI and noticed how bad some LED's are in that department. Im now running a handful of 94 CRI bulds and a bunch of 84 CRI bulbs. I actually found one single 96 CRI bulb on ebay a few years ago that im using in her make up area now and she loves it

 

[DCal430]

I am f

Basic design guideline for an LED is, the brighter it is, the less efficient it gets. That's why efficiency costs more, because they can drive the same total lumens with less wattage by simply adding more LEDS inside the bulb.

I am finding the exact opposite to be true. My lowest lumens bulbs are my least efficient at only around 60lm/watt and my brightest bulb is the most efficient at over 120lm/watt.

 

[dullard]

I am f
I am finding the exact opposite to be true. My lowest lumens bulbs are my least efficient at only around 60lm/watt and my brightest bulb is the most efficient at over 120lm/watt.

That was answered in the link in the first reply to the thread. https://redirect.viglink.com/?format=go&jsonp=vglnk_148667587875312&key=08a8dcb30b28eed5c1da2bd64b4ca559&libId=iyywfian0101045l000DAlpgmkwy4&loc=http://www.portvapes.co.uk/?id=Latest-exam-1Z0-876-Dumps&exid=threads/what-is-with-led-light-efficiency.2498529/&v=1&out=https://goo.gl/images/04D3wn&ref=http://www.portvapes.co.uk/?id=Latest-exam-1Z0-876-Dumps&exid=threads/what-is-with-led-light-efficiency.2498529/page-3&title=What is with LED light efficiency? - AnandTech Forums&txt=https://goo.gl/images/04D3wn


Click on the link and look at the graph. Suppose you wanted 100 lm with that particular LED. You have several options.
1) Use one of those LEDs at 350 mA to get 100 lm. It has an efficiency of about 88 lm/W from the graph.
2) Use two of those LEDs at 155 mA to get 50 lm each (total of 100 lm). Each has an efficiency of 107 lm/W.
3) Use three of those LEDs at 100 mA to get 33.3 lm each (total of 100 lm). Each has an efficiency of 114 lm/W.
3) Use four of those LEDs at 75 mA to get 25 lm each (total of 100 lm). Each has an efficiency of 117 lm/W.
...
10) Use 10 of those LEDs at 30 mA to get 10 lm each (total of 100 lm). Each has an efficiency of 122 lm/W.

The efficiency is simply a matter of how much money they want to put into raw materials. 10 LEDs is a lot more expensive than 1 LED. Your most efficient bulb was $20. Meaning they had the spare money to put in more than just one bright LEDs. They could put in say 10 dimmer LEDs.

That was just one example of an LED. Others are similar though. I don't know what LED or how many your $20 T8 bulb is using. But a couple expensive high quality LEDs or several cheaper LEDs can be the most efficient compared to just taking a single LED and running it bright.

 

[DCal430]

Th

That was answered in the link in the first reply to the thread. https://redirect.viglink.com/?format=go&jsonp=vglnk_148667587875312&key=08a8dcb30b28eed5c1da2bd64b4ca559&libId=iyywfian0101045l000DAlpgmkwy4&loc=http://www.portvapes.co.uk/?id=Latest-exam-1Z0-876-Dumps&exid=threads/what-is-with-led-light-efficiency.2498529/&v=1&out=https://goo.gl/images/04D3wn&ref=http://www.portvapes.co.uk/?id=Latest-exam-1Z0-876-Dumps&exid=threads/what-is-with-led-light-efficiency.2498529/page-3&title=What is with LED light efficiency? - AnandTech Forums&txt=https://goo.gl/images/04D3wn


Click on the link and look at the graph. Suppose you wanted 100 lm with that particular LED. You have several options.
1) Use one of those LEDs at 350 mA to get 100 lm. It has an efficiency of about 88 lm/W from the graph.
2) Use two of those LEDs at 155 mA to get 50 lm each (total of 100 lm). Each has an efficiency of 107 lm/W.
3) Use three of those LEDs at 100 mA to get 33.3 lm each (total of 100 lm). Each has an efficiency of 114 lm/W.
3) Use four of those LEDs at 75 mA to get 25 lm each (total of 100 lm). Each has an efficiency of 117 lm/W.
...
10) Use 10 of those LEDs at 30 mA to get 10 lm each (total of 100 lm). Each has an efficiency of 122 lm/W.

The efficiency is simply a matter of how much money they want to put into raw materials. 10 LEDs is a lot more expensive than 1 LED. Your most efficient bulb was $20. Meaning they had the spare money to put in more than just one bright LEDs. They could put in say 10 dimmer LEDs.

That was just one example of an LED. Others are similar though. I don't know what LED or how many your $20 T8 bulb is using. But a couple expensive high quality LEDs or several cheaper LEDs can be the most efficient compared to just taking a single LED and running it bright.

This makes sense. The T8 bulb is very long 4 feet and has multiple rows of LED along its entire length it has a lot of LEDs. The candelabra bulb is very small. I doubt it could fit more than a few LEDs in it.

 

[agent00f]

I am finding the exact opposite to be true. My lowest lumens bulbs are my least efficient at only around 60lm/watt and my brightest bulb is the most efficient at over 120lm/watt.

That's because you're not comparing like to like. Low output and low efficiency often correlate because they're the cheap bulbs with cheap low efficacy leds.

 

[JEDI]

I purchased a bunch of LED lights recently, and I noticed the efficiency really varies on them. Some are very good, and others are very poor. I have one LED light that uses only 17.5 watts, but produces about 2,300 lumens, so about 131 lumens/watt. Then I have these LED that are 5 watts, but only produce about 300 lumens, so only only 60 lumens/watt. I have other LED bulbs that are around 80-100 lumens/watt. What is what this wide range in efficiency, some LED bulbs seem worst than CFLs.

yeah, 60w equivalent LED's use 9w.
60w equivalent cfl's are 13w and are 1/3 the price of LED's.

so im sticking w/cfl's until LED prices come down

 

[stormkroe]

yeah, 60w equivalent LED's use 9w.
60w equivalent cfl's are 13w and are 1/3 the price of LED's.

so im sticking w/cfl's until LED prices come down

But cfls have less than a third the L70 of leds. Lighting is a huge part of my business, and I've found that led is finally the right call to make in almost all scenarios (efficiency and ruggedness have been overstated for years, but reality finally meets the claims).

 

[Red Squirrel]

Yeah leds have really come a long way in the past couple years as far as general lighting. I was at an arena out of town a few weeks ago and noticed that the lights they used were LEDs. It was a nice white light and very bright. Noticed a lot of outdoor building lights are LED now too and they changed out all our street lights to LED a few years back too. I figured the cold would be an issue for them since they don't produce as much heat, but I guess the big fixtures still generate enough heat to keep themselves warm and keep snow off. If I had to guess the street lights are probably like 50w or so, vs the 500w HPS they replaced.

 

[Mr.IncrediblyBored]

Yeah leds have really come a long way in the past couple years as far as general lighting. I was at an arena out of town a few weeks ago and noticed that the lights they used were LEDs. It was a nice white light and very bright. Noticed a lot of outdoor building lights are LED now too and they changed out all our street lights to LED a few years back too. I figured the cold would be an issue for them since they don't produce as much heat, but I guess the big fixtures still generate enough heat to keep themselves warm and keep snow off. If I had to guess the street lights are probably like 50w or so, vs the 500w HPS they replaced.

I doubt the LED is much more efficient than the old HPS lamps. Sodium lamps have great light output. They just have horrible color temperature and CRI.

 

[lxskllr]

But cfls have less than a third the L70 of leds. Lighting is a huge part of my business, and I've found that led is finally the right call to make in almost all scenarios (efficiency and ruggedness have been overstated for years, but reality finally meets the claims).

cfls are ugly as shit, and that's only one of their problems. Fluorescent lighting makes me angry. My next project will be replacing the fluorescent tubes in one of my bathrooms with leds.

 

[Imp]

cfls are ugly as shit, and that's only one of their problems. Fluorescent lighting makes me angry. My next project will be replacing the fluorescent tubes in one of my bathrooms with leds.

I replaced 75% of my CFL bulbs last summer. Best decision ever.

CFLs: ugly pieces of shit that collect dead insects and webs, their plastic bases turn yellow or look scorched over time, the bulbs can blow open, and if you break one, have fun cleaning up the mercury. Not to mention the warm up time.

 

[Muse]

Had to make decision yesterday at Home Depot:

8 Ecosmart 60watt equivalent Soft White 2700 color temperature 800lm undimmable for $11.38
9 years expected at 3hr/day

2 Philips 60watt equivalent Soft White 2700 color temperature 800lm dimmable for $7.97
22 years expected at 3hr/day

I chose the Philips. It's for my kitchen. Not sure I like the warm color, am wondering how I'd like 3000 color temperature bulbs.

I have no idea concerning Ecosmart bulbs, didn't remember them mentioned in this thread.

I saw people mentioning here that they picked up Philips bulbs $5 for two at Home Depot on sale, but I haven't been hitting HD much, so figured my chances of spotting a sale on them isn't good. They had a three pack of the same bulb for $17.97. Two for $7.97 beat that pretty handily.

I'm wondering something:

Do the number of on/off cycles impact the longevity of these LED bulbs or is it just the on-hours? IOW, does it make sense to turn them on/off a lot or just leave them on?

 

[lxskllr]

afaik, power cycling won't affect life. The longer they're off, the longer they last.

 

[Red Squirrel]

Yeah CFLs are affected by cycling but most LEDs are not, they're more "passive" in nature while CFLs rely on an electro chemical reaction, if that's even the right word for it. I personally have no issues with CFLs but as mine die I will replace with LED. I like the ones that look like old style light bulbs, before the only ones you could get were for spot lights but they have all sorts now and they're not that expensive. Most should be dimmable too. Though depending on the type of PSU inside and the build quality that's really the main part that will fail over time. If they use Wun Hung Lo parts that were scrounged up from bargain bins in the Shenzen market then they may fail prematurely.

 

[dullard]

Do the number of on/off cycles impact the longevity of these LED bulbs or is it just the on-hours? IOW, does it make sense to turn them on/off a lot or just leave them on?

Dimmable LEDs are usually dimmed by turning them on/off hundreds if not thousands of times per second. They still last quite a long time.

So, no, I wouldn't worry about turning LEDs on or off any more. They aren't like regular incandescent bulbs that go through massive temperature changes and the associated stress which tears them apart.

 

[Aharami]

this was quite an informative thread.

 

[lxskllr]

Dimmable LEDs are usually dimmed by turning them on/off hundreds if not thousands of times per second. They still last quite a long time.

So, no, I wouldn't worry about turning LEDs on or off any more. They aren't like regular incandescent bulbs that go through massive temperature changes and the associated stress which tears them apart.

One thing I was thinking is temp changes could break solder joints after awhile. I had a led spot light go bad like that. It works til it heats up, then shuts off. If you whack it, it'll light for a minute or two, then shut off again. I'm waiting til one of the incandescent lights goes in the bathroom, and I'll use it there. Since the light isn't on as long, it may work ok.

 

[Muse]

One thing I was thinking is temp changes could break solder joints after awhile. I had a led spot light go bad like that. It works til it heats up, then shuts off. If you whack it, it'll light for a minute or two, then shut off again. I'm waiting til one of the incandescent lights goes in the bathroom, and I'll use it there. Since the light isn't on as long, it may work ok.

A box of LEDs I was looking at (perhaps the one I bought) said you shouldn't put them in an enclosed fixture. I inferred that heat is not well tolerated.

 

[Imp]

A box of LEDs I was looking at (perhaps the one I bought) said you shouldn't put them in an enclosed fixture. I inferred that heat is not well tolerated.

I think I've seen the same labels on CFLs. Not an electrical engineer but LEDs and CFLs have electronic shit inside that needs heat management. There should be ones designed for enclosed fixtures though. How well they work is another story.

 

[Aharami]

anyone have these? Saw them at costco for $6.99 for a two pack.

https://www.amazon.com/Feit-Electri...scsubtag=ffe1c8ac080311e7885aeac75121984d0INT