What is with LED light efficiency?

[DCal430]

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.

 

[dullard]

Money and longevity.

Good LEDs cost more for a reason. Also, LEDs can put out a very wide range of light just by giving them different currents, but that additional light comes with additional heat and usually lower efficiency. https://goo.gl/images/04D3wn

Heat costs money to pull out (more design cost, more metal to pull it away probably with more machining time, probably metal PCBs which are expensive compared to fiberglass). Finally, a manufacturer may just choose to run a bit less current for longer battery life or longer LED life.

So the manufacturer has to decide between: more light or more efficiency or lower costs.

 

[dullard]

Also, efficiency isn't the reason to go for LED over CFL. As you said, the efficiency is often about the same.

You go for LEDs for nearly instant light (virtually all CFLs take some noticible time to warm up, some much longer than others), usually easier ability to dim (although you have to check the lightbulb as cheap LED bulbs are not able to be dimmed), sometimes the ability to choose the color, and usually a far longer bulb life.

 

[mizzou]

I went to sams club yesterday to buy some CFL's and all they had were $5 and $10 LED bulbs

I'm not ready for the switch yet.

 

[dullard]

I went to sams club yesterday to buy some CFL's and all they had were $5 and $10 LED bulbs

I'm not ready for the switch yet.

You need to watch the sales. Also, LEDs are directional light, so they are cheapest to make in recessed lighting format which requires directional light. So start with recessed lights, they are often down to $2 or less per bulb.

 

[13Gigatons]

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

 

[Ken g6]

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

The ones I got seem OK. But I got the last package of an older, less-efficient, longer-warrantied version. Their current bulbs might not be as good.

 

[DCal430]

Money and longevity.

Good LEDs cost more for a reason. Also, LEDs can put out a very wide range of light just by giving them different currents, but that additional light comes with additional heat and usually lower efficiency. https://goo.gl/images/04D3wn

Heat costs money to pull out (more design cost, more metal to pull it away probably with more machining time, probably metal PCBs which are expensive compared to fiberglass). Finally, a manufacturer may just choose to run a bit less current for longer battery life or longer LED life.

So the manufacturer has to decide between: more light or more efficiency or lower costs.

Though in my case the less brught lights are less efficient. The 130lm/watt are the brightest light I have. Cost wise though they are by the most expensive. Costing close to $20 each. The 60lm/watt bulbs were just under $3 each.

I wonder if fixture matters too. The 2,300 lumens are tube lights that go in a T8 fluorescent fixture. Two bulbs with the ballast use about 35 watt and deliver 4600 lumens of light. The inefficient LED are candelabra bulbs.

 

[Imp]

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

The Wal-Mart bulbs I saw were mostly from GE. They were more expensive than the ones I bought from Ikea and Philips, IIRC. Haven't tried them so can't say. My Ikea and Philips bulbs are okay.

 

[DCal430]

I thought Costco only sold the best but the FEIT bulbs from Costco are crap. Many of mine have died in less than a year.

 

[DCal430]

The Wal-Mart bulbs I saw were mostly from GE. They were more expensive than the ones I bought from Ikea and Philips, IIRC. Haven't tried them so can't say. My Ikea and Philips bulbs are okay.

My Phillips are actually my best bulb. I haven't seen bulbs with her higher efficiency rating than Phillips instantFit.

 

[Imp]

My Phillips are actually my best bulb. I haven't seen bulbs with her higher efficiency rating than Phillips instantFit.

Love Philips. They were one of the first ones to come out with "regular" looking LED bulbs that were somewhat reasonable in cost. The one I bought for $25 back in 2013 is still kicking and gets like 8 hours a day usage.

My Ikea bulbs were the cheapest. Newest 400 lumen ones I got were $2 a pop. They've been working well for months.

 

[Pulsar]

Another major problem in lighting is the measurement of the light provided. An inch is an inch unless you're in metric land. But a lumen? Whoah boy..... I'm not going to even start going into that. Just take a look at all the flashlights that use the exact same LED but advertise up to an order of magnitude different brightnesses. It's almost criminal.

I won't buy a light bulb unless I see it turned on.

 

[Red Squirrel]

LED modules themselves vary a lot in efficiency. One thing I noticed though is that lumen measurement seems to be all over the place in general. For example you can buy a LED flashlight that is 3,000 lumens, but the LED module itself says maybe 200 lumens in the datasheet. So they are obviously measuring differently and fudging the numbers while the datasheet is probably providing a conservative value without overdriving the module.

 

[chimaxi83]

OP, have you tried buying bulbs outside of North Korea? Try it and report back.

 

[Red Squirrel]

Oh and avoid Amazon and Ebay. Most of those are direct from China and have zero safety approvals. If it burns your house down your insurance won't cover it. And it probably will burn your house down. Some of those have exposed mains and questionable power supplies.

 

[Schfifty Five]

I've had good luck with the Philips brand LED lightbulbs from Home Depot. They sometimes go on sale for like < $10 for a 4 pk. I like em so far. Can't tell the difference between those and regular bulbs.

 

[agent00f]

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.

The major "name-brand" manufacturers use similar level of tech which shouldn't vary too much. There's a difference in efficacy between differing temp/hue of light because white led's only emit blue and any red output is through the tinted phosphor coating which creates some loss. More red tint = more loss. That said the tech's been advancing fast enough that it's not uncommon for bulbs either from or using leds from a year ago to be somewhat dated.

 

[esquared]

I bought the bulbs based in efficiency (lumens/watts), higher efficiency, higher cost.
I changed over from those crappy (IMO) CFL, when the price per bulb of decent LEDs hit 10.00 bulb, nearly 3 years ago.

Light is great compared to the yellowish CFLs. All of the Crees and Philips I bought were over 90 lumens/watt.
I am looking at a Philips standard 60W equivalent box, that uses 8.5 W for 800 lumens. These were on sale at Home depot for 5.00 for a two pack.
The Cree's I have are also over 98-117lumens/watt
http://lighting.cree.com/products/indoor/lamps/a19-series
http://lighting.cree.com/products/indoor/lamps/a21-series

Looks like they dropped their warranty down from 10 years to 5 years. I have a couple of the A21 three-ways (30W/60W/100W) and they
work well.
The three way are (107/117/98 lumens watt)

On the other hand, the cheap LEDs you see at Fry's and Costo have , still, lower efficiency.
http://www.frys.com/product/8692810
75lumens/watt
http://www.frys.com/product/8688850
80 lumens/watt.

Feit from Costco are still lower efficiency.
https://www.costco.com/Feit-LED-A-Lamp-40W-Replacement-Soft-White-12-pack-.product.100307310.html
64 lumens/watt
https://www.costco.com/Feit-LED-60W-Replacement-Soft-White,-12-pack-.product.100329428.html
84 lumens/watt

 

[Staples]

As with CFL bulbs, there is an exponential increase in efficiency the more power they draw.

 

[EliteRetard]

You can buy those high efficiency emitters from Cree for dirt cheap. You can get an XM-L2 around $6, make the bulb for less than $10.

 

[x26]

Love Philips. They were one of the first ones to come out with "regular" looking LED bulbs that were somewhat reasonable in cost. The one I bought for $25 back in 2013 is still kicking and gets like 8 hours a day usage.

My Phillips are actually my best bulb. I haven't seen bulbs with her higher efficiency rating than Phillips instantFit.

Love Philips. They were one of the first ones to come out with "regular" looking LED bulbs that were somewhat reasonable in cost. The one I bought for $25 back in 2013 is still kicking and gets like 8 hours a day usage.

I love My Philips!!

 

[OverVolt]

Efficiency really doesn't bother me. All I care about is lighting quality.

So, actually someone mentioned the Great Value bulbs. I can't remember the actual manufacturer, but I remember researching it before and they were actually very good quality bulbs, one of the few that are certified for enclosed fixtures.

Personally I'm loving 40/60(800 lumen)/100 "watt" LEDs for home lighting. I'm loving the soft 2700k light output without alot of red/blue glare. I'm loving the option to buy dimmable LEDs. Overall I'm really pleased with LEDs over CFLs.

Its actually kinda motivated me to care about having a soft white 2700k covered fixture in the bathroom and maybe some bare soft white 2700k's "100w" bulbs in the living room fan, etc. etc.

 

[DCal430]

One thing is I wished LED could dim as well as incandescent. The dimmable range of LEDs are still limited compared to incandescent, and many dimmable LED manufactures allow for some shimmering. Dimmable LEDs can have issue with many dimmers. Compatibility is very subjective too.

 

[agent00f]

As with CFL bulbs, there is an exponential increase in efficiency the more power they draw.

LED's are the opposite; efficacy declines with current.

Efficiency really doesn't bother me. All I care about is lighting quality.

So, actually someone mentioned the Great Value bulbs. I can't remember the actual manufacturer, but I remember researching it before and they were actually very good quality bulbs, one of the few that are certified for enclosed fixtures.

Personally I'm loving 40/60(800 lumen)/100 "watt" LEDs for home lighting. I'm loving the soft 2700k light output without alot of red/blue glare. I'm loving the option to buy dimmable LEDs. Overall I'm really pleased with LEDs over CFLs.

Its actually kinda motivated me to care about having a soft white 2700k covered fixture in the bathroom and maybe some bare soft white 2700k's "100w" bulbs in the living room fan, etc. etc.

Not all 2700k or whatever are created equal as one scalar cannot fully encapsulate the emission across a spectrum. Generally, more full spectrum implies greater photon energy conversion loss, ie lower efficacy/"efficiency".

One thing is I wished LED could dim as well as incandescent. The dimmable range of LEDs are still limited compared to incandescent, and many dimmable LED manufactures allow for some shimmering. Dimmable LEDs can have issue with many dimmers. Compatibility is very subjective too.

Dimming LED's is a tricky business since on the led side of the circuit color output changes with current, so there's a tradeoff there of how to cut power, either by lowering current for greater efficacy as mentioned above, or switching the led on/off rapidly (more common, but often done at insufficient frequency for whatever reason). On the dimmer side, "dimming" circuits designed for incan's also vary in the same way, some lower voltage/current, but most also cycle the power in some matter, so the power converter on-board has to take into account various possibilities.