DC LED efficiency

[Vern Faulkner]

Alert readers will note the "DC" here, as I'm well aware of the CFL/LED efficiency discussions and what they mean.

Let me put things in this light: I am fully aware that AC LEDs are inefficient, if and only if for the reason they are taking AC and converting it to DC. Throw in the inefficiencies created when DC is turned into 120 VAC, and yeah, I see the losses accumulate.

What I'm looking for are suggestions/leads on DC LEDs that may function in a residential setting. Looking at spot lighting, kitchen lighting. I don't mind 12vdc systems, as I can run two of those in series if/when we do the new house and the 24vdc system that seems to be the one we're aiming at.

To contribute, I've ordered a 10-30 vdc LED light out of Singapore: cost me $15. I'll do some tests and report back, perhaps with pictures (with a camera set on manual to lock down aperture/exposure and thus provide a real sense of illumination, compared to a CFL and the handy-dandy kerosene lamp, just for giggles and grins.

The current plan is to look at a split lighting system: CFL for when you just gotta have light, and LED for localized lighting. As an aside, we've just put a pair of battery-powered, portable LED sticks (four LEDs, powered by three AAA batteries) over our stove. This is a darker, yet perfectly functional replacement for the incandescent (three xenon bulbs) fixture over the sink.

This is part of our ongoing test of solar (our living room is partly off-grid, at the moment) this winter. Currently, about the only major thing we're running off the batteries is a lamp (50 watt, three-stage CFL) and a few other things as we gain comfort in the energy draw and recharging rates, and so on.

[Sunking]

Well what you are going to find if you know what you are doing is going to be disappointing. Cree has the most efficient LED on the market period, there are none better at any price point. They claim 160 L/w when operated at 2 watts. Problem is that is a lab rating inside a refrigerator more or less keeping lamp temperature at a cool 10 Centigrade. LED intensity drops dramatically as the base heats up to as much as 75% which is not included in the specs. It is also with the 15 degree bean angle and if you get off the ocus point the light intensity drops dramatically. They make great flashlights but poor room lighting.

The other little dirty secret is the manufactures tell you l/w efficiency of the LED only, which is all they can tell you because they do not make the fixtures and drivers. So any power consumed by the drivers or ballast is not specified or included.

When all added up LEDs ar not much more efficient than incandescent bulbs., and not as good as quality CFL lamps. They dot even come close to the king of indoor lighting the T5HO High Bay Lighting. Go into any modern indoor sports arena, warehouse, or office and you will find only T5HO High Bay lighting. There are a ton of T5 lighting systems for your home and office. With ballast and line losses you are looking at 105 L/Watt in a full spherical illumination, not a focused beam of LED.

FWIW th eFederal Government will not allow LED lighting in any public building. They are too inefficient. All lighting in government buildings will be either T5, T8, or CFL. That ought to tell you something.

[SunEagle]

Well what you are going to find if you know what you are doing is going to be disappointing. Cree has the most efficient LED on the market period, there are none better at any price point. They claim 160 L/w when operated at 2 watts. Problem is that is a lab rating inside a refrigerator more or less keeping lamp temperature at a cool 10 Centigrade. LED intensity drops dramatically as the base heats up to as much as 75% which is not included in the specs. It is also with the 15 degree bean angle and if you get off the ocus point the light intensity drops dramatically. They make great flashlights but poor room lighting.

The other little dirty secret is the manufactures tell you l/w efficiency of the LED only, which is all they can tell you because they do not make the fixtures and drivers. So any power consumed by the drivers or ballast is not specified or included.

When all added up LEDs ar not much more efficient than incandescent bulbs., and not as good as quality CFL lamps. They dot even come close to the king of indoor lighting the T5HO High Bay Lighting. Go into any modern indoor sports arena, warehouse, or office and you will find only T5HO High Bay lighting. There are a ton of T5 lighting systems for your home and office. With ballast and line losses you are looking at 105 L/Watt in a full spherical illumination, not a focused beam of LED.

FWIW th eFederal Government will not allow LED lighting in any public building. They are too inefficient. All lighting in government buildings will be either T5, T8, or CFL. That ought to tell you something.

I agree with Sunking that the T5 fluorescent lamps and ballasts have shown to be the best lighting for your dollars. These work great in office areas as well as large production facilities.

Where I disagree with him is the use of LED lighting in the home. I feel they provide the required light needed for a lot less wattage used. I converted my old kitchen lighting which consisted of (10) 4 foot 34watt and (2) 2 foot 20 watt fluorescent lamps to (8) 4 watt ceiling LED and (3) 2 watt hanging LED lamps. I dropped the total wattage from almost 400 watts to 38 watts still have enough light to please the wife. Along with lowing the lamp wattage I have also decreased the amount of heat the lights give off. The kitchen is bright and cooler.

Besides the kitchen I have converted the twin 4 foot fluorescent fixture in our Laundry room (~70 watts) to a single 4 foot 10 watt LED lamp and the 2 foot 20 watt fluorescent lights in our pantry & 4 clothing closets to 2 foot 8 watt LEDs. A drop from ~170 total watts to 40 watts without noticing any reduction of light output.

I'm not saying LED's are the way to go for everyone. I just saying that with a little research you can find an LED that will work in home lighting without noticeable loss of light lumens.

[inetdog]

I'm not saying LED's are the way to go for everyone. I just saying that with a little research you can find an LED that will work in home lighting without noticeable loss of light lumens.

Even with the currently available options, I strongly favor LED (using self-ballasted 120 volt bulbs) for safety-related lighting like hallways and stairways. The feature that makes them most attractive is the instant-on full intensity light. For general room and task lighting, I can wait for a CFL to reach full brightness, although I will mix one LED with the rest CFL in a multi-bulb fixture for the same reason.

GE, I believe, offers a CFL with an internal halogen bulb that comes on during the warm-up time of the CFL and then turns off, but consumer testing shows that the life of the unit is severely reduced if you use it with short on-off cycles. And that is a very likely condition people would want to use them for.

[Sunking]

Even with the currently available options, I strongly favor LED (using self-ballasted 120 volt bulbs) for safety-related lighting like hallways and stairways. The feature that makes them most attractive is the instant-on full intensity light.

The flip side as the LED heats up, they dim as they reach operating temp. LED's are good for Task specific lighting where you need to focus a beam because the light is coherent like a Lazer. But for area lighting has a long way to go. For area lighting, they are not much better than incandescent, and fall short of even mediocre CFL's, and cannot touch T5 florescent.

[inetdog]

The flip side as the LED heats up, they dim as they reach operating temp. LED's are good for Task specific lighting where you need to focus a beam because the light is coherent like a Lazer. But for area lighting has a long way to go. For area lighting, they are not much better than incandescent, and fall short of even mediocre CFL's, and cannot touch T5 florescent.

I am currently using Ecosmart 40 watt replacement bulbs. They use 8 watts (including driver, since this is an integrated assembly), have a color temp of 3000K and produce 430 lumens.
They do not get any hotter (actually appear to run cooler) than a comparable CFL and I have not seen any dimming yet. I take the claimed 46 year lifespan (at 3 hours per day) with a grain of salt, but I have never had a CFL come anywhere close to its rated lifespan. They are a type A shape, but because of the driver and heat sink base only have an effective coverage angle of more than one hemisphere.
And they work fine with my conventional dimmers, giving a much better performance at low light settings than any CFL I have tried, even with a CFL-rated dimmer. Still not as smoothly dimmable as incandescent and when mixing incandescent and LED on one dimmer, I have not found anything that works well yet.

[Sunking]

Inetdog if you want some info on professional LED lighting fixtures I can kook you up. A few years ago we did a Walmart. However since then they replaced it all with T5. Made the meat look purple and used too much power.

[inetdog]

Inetdog if you want some info on professional LED lighting fixtures I can kook you up. A few years ago we did a Walmart. However since then they replaced it all with T5. Made the meat look purple and used too much power.

Sure, always looking for new sources. (And I do not like purple meat. ) I also have a few tactical flashlights with two different color profile Cree LEDs, so I am familiar with the color rendering issues. The ecosmart is actually quite good in that respect too. At $9 each as a loss leader at Home Despot, I can afford to play with these.

I realize that I could get higher efficiency from a T5 fixture or a dedicated LED fixture, but since we are on-grid, the wife's appearance preferences are the biggest determining factor.

[Vern Faulkner]

Apparently, I wasn't clear enough in my original post. I'm not looking at re-starting the 120 VAC LED versus 120 VAC CFL debate. I've seen the data, and I know what folks are saying. Hence, folks will note that I had already stated a committment to using 120 VAC CFL bulbs for general area lighting. OK? So attempts to sell me on CFLs are wasted: they're already in the plan.

I am looking at area and spot-specific LED lighting solutions that ARE NOT 120 VAC. In short, I am looking for things that may be of interest that are 24 VDC powered, or 12 VAC powered that may be of suitable small-scale, low-light use.

The example I used above, and I will use again, is in our kitchen, where we have a set of AAA-powered LED lights over the stove. THey are replacing the function of a big ol incandescent fixture we'd leave on so we could fumble around the kitchen without putting on all the big lights. That's what I am after.

As an aside, I see the CFL/LED bulb discussion as a symptom of a larger issue: we're light-greedy. In the goold ol' days, before Edison and electricity, we used the same light-producing tool I am using right now beside the computer: a kerosene light. I don't mind fewer lumens in a smaller area. I don't need to recreate the light output of a 500-watt halogen. The 50-watt, three-step CFL we have in the corner lights up half the living room perfectly. The 11 Watt LED in the lower lamp has a super-bright and tight beam that makes it ideal for doing cross-stitch, or reading. Horses for courses, and all that.

[SunEagle]

Sure, always looking for new sources. (And I do not like purple meat. ) I also have a few tactical flashlights with two different color profile Cree LEDs, so I am familiar with the color rendering issues. The ecosmart is actually quite good in that respect too. At $9 each as a loss leader at Home Despot, I can afford to play with these.

I realize that I could get higher efficiency from a T5 fixture or a dedicated LED fixture, but since we are on-grid, the wife's appearance preferences are the biggest determining factor.

I have to agree with the wife being a determining factor. She did not want any fluorescent in the new kitchen period!!!!

I have been using the 4 watt recessed LED lamps for about 3 years without any noticeable dimming. They do put out some heat but no where near as much as the old fluorescent or even a low wattage CLF. The 2 watt candelabra LED's that I have are always cool to the touch no matter how long they are on which is usually 18 hours per day.

[inetdog]

I have to agree with the wife being a determining factor. She did not want any fluorescent in the new kitchen period!!!!

I have been using the 4 watt recessed LED lamps for about 3 years without any noticeable dimming. They do put out some heat but no where near as much as the old fluorescent or even a low wattage CLF. The 2 watt candelabra LED's that I have are always cool to the touch no matter how long they are on which is usually 18 hours per day.

On the other hand, about two years ago Costco had an attractively low price offer on LED PAR replacements and LED candelabra bulb replacements and had to recall them all because the light output dropped like a shot over the first few hundred hours of continuous use. Not what you want for a night light.
So there is definitely a wide range of quality from LEDs.

[SunEagle]

Apparently, I wasn't clear enough in my original post. I'm not looking at re-starting the 120 VAC LED versus 120 VAC CFL debate. I've seen the data, and I know what folks are saying. Hence, folks will note that I had already stated a committment to using 120 VAC CFL bulbs for general area lighting. OK? So attempts to sell me on CFLs are wasted: they're already in the plan.

I am looking at area and spot-specific LED lighting solutions that ARE NOT 120 VAC. In short, I am looking for things that may be of interest that are 24 VDC powered, or 12 VAC powered that may be of suitable small-scale, low-light use.

The example I used above, and I will use again, is in our kitchen, where we have a set of AAA-powered LED lights over the stove. THey are replacing the function of a big ol incandescent fixture we'd leave on so we could fumble around the kitchen without putting on all the big lights. That's what I am after.

As an aside, I see the CFL/LED bulb discussion as a symptom of a larger issue: we're light-greedy. In the goold ol' days, before Edison and electricity, we used the same light-producing tool I am using right now beside the computer: a kerosene light. I don't mind fewer lumens in a smaller area. I don't need to recreate the light output of a 500-watt halogen. The 50-watt, three-step CFL we have in the corner lights up half the living room perfectly. The 11 Watt LED in the lower lamp has a super-bright and tight beam that makes it ideal for doing cross-stitch, or reading. Horses for courses, and all that.

I understand your desire for DC led type lamps. I actually purchase a kit that was designed for lighting under an automobile. It consists of (2) 4 foot and (2) 2 foot LED tubes. They all connect to a control box which is powered by 12 volts. The control box has a number of stobing affects which was supposed to get peoples attention but it does have a full on and off switch which is what I will be using. If you are interested the kit can be found on eBay sold by "Solar Products626" for about $60.

[Vern Faulkner]

I understand your desire for DC led type lamps. I actually purchase a kit that was designed for lighting under an automobile. It consists of (2) 4 foot and (2) 2 foot LED tubes. They all connect to a control box which is powered by 12 volts. The control box has a number of stobing affects which was supposed to get peoples attention but it does have a full on and off switch which is what I will be using. If you are interested the kit can be found on eBay sold by "Solar Products626" for about $60.

Currently quite stoked with the output of a 25-LED cluster 10-30volt light that is putting out a decent amount of light at 3 watts power consumption. May take a reasonable picture (with manual settings) to demonstrate.

[woundedeagle]

Well what you are going to find if you know what you are doing is going to be disappointing. Cree has the most efficient LED on the market period, there are none better at any price point. They claim 160 L/w when operated at 2 watts. Problem is that is a lab rating inside a refrigerator more or less keeping lamp temperature at a cool 10 Centigrade. LED intensity drops dramatically as the base heats up to as much as 75% which is not included in the specs. It is also with the 15 degree bean angle and if you get off the ocus point the light intensity drops dramatically. They make great flashlights but poor room lighting.

The other little dirty secret is the manufactures tell you l/w efficiency of the LED only, which is all they can tell you because they do not make the fixtures and drivers. So any power consumed by the drivers or ballast is not specified or included.

When all added up LEDs ar not much more efficient than incandescent bulbs., and not as good as quality CFL lamps. They dot even come close to the king of indoor lighting the T5HO High Bay Lighting. Go into any modern indoor sports arena, warehouse, or office and you will find only T5HO High Bay lighting. There are a ton of T5 lighting systems for your home and office. With ballast and line losses you are looking at 105 L/Watt in a full spherical illumination, not a focused beam of LED.

FWIW th eFederal Government will not allow LED lighting in any public building. They are too inefficient. All lighting in government buildings will be either T5, T8, or CFL. That ought to tell you something.

I agree with your point.
The lighting guy always tell you the LED have 100 Lm/W or even higher, but this is " half true" , they have not told you this data is gethered from the pure LED chips, not from the whole LED fixture!!! The execurate data should be 70-80 Lm/W for bulb, 50-75 Lm/W for spot light.
the lighting guy will also will also tell you the LED have the life span of 35,000 hours. It's true, but it's under some "condition" such as: the driver is at good quality, the fixture is will good heat dissipation,ext.

Any way, LED is good for energy saving and good for envioronmnet, but we must know more about it before we let it come into to our life

Mod note - forget the links

[FunGas]

I put LED PAR style spots over the workbench, due to their quiet radio emission, they're very good, but I wish I'd used more, creating overlapping beams.
Later on, I fitted LED strip lights under the bench, to illuminate the floor, which was very good at hiding anything that got dropped...

So, LED's are nice, but don't usually have a wide enough beam to be a real replacement for "normal" lighting.