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Last post Author Topic: Our experiences with LED light bulb replacements  (Read 16742 times)

CWuestefeld

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Re: Our experiences with LED light bulb replacements
« Reply #25 on: May 20, 2014, 06:53:33 PM »
But if I remember what little I do correctly, the total amount of heat generated by any electronic device is a function of its resistance, not the interplay of voltage, wattage and amperage

I think you're overthinking it. It just comes down to basic conservation of energy. The amount of energy you put into the device is the same as what comes out of it. The only question is in what form is the energy emitted? But since we're looking at devices that are emitting roughly the same amount of light, we can even discount that portion of it to compare the total amount of heat generated

Technically, the total amount of energy being expended easy to figure. In the USA, the voltage should be 110V. The amount of electrical energy you're putting in is the amps, which you can calculate by dividing the bulb's wattage by the volts. We don't just how much is being turned into light, but it's a small number and similar across all the devices anyway. So it's a decent estimate to compare the relative amount of heat generated as the relative wattage of each device.

Henfracar

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Re: Our experiences with LED light bulb replacements
« Reply #26 on: May 20, 2014, 07:24:01 PM »
Last year I replaced my kitchen under-cabinet lights (P11s) with LEDs.
These are the strip type lights and can be custom made in whatever lengths you require, although Walmart carries them now in varying lengths.
 They required 12 volt DC current and a 110 to 12 volt adaptor (5 amps) was installed to supply same.
I reused the swithes from the original P11 fittings to operate each light individually, and am quite happy with the coolness of the fixtures and the lighting spread afforded.

barney

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Re: Our experiences with LED light bulb replacements
« Reply #27 on: May 20, 2014, 07:25:12 PM »
It seems from what I'm reading now that this 60W limit is not so much about electricity limit, but about how much heat the fixture bases can take.  And if that's true, and LED bulbs generate huge heat at the fixture base, I may be in trouble.

This is quite true, but there are caveats.  For instance, my ceiling fixtures say 60W only, no higher.  However, they are embedded ceiling fixtures with a frosted glass cover.  The 60W limit is not only due to heat, but also due to bulb burnout in an enclosed environment.  I can put a 100W incandescent in the fixture, but it will die of heat exhaustion in about a third of the time that a 60W will last.  With the CFL or LED bulbs, an infrared thermometer shows a significant captured heat reduction.  CFLs show less temp than the LEDs, but as was mentioned earlier, they're a lot more damaging to the environment.  Well, at least we know that particular damage - LEDs have yet to be EPAed  :-\.

I also used the IR gun on several desk lamps.  Heat reduction, compared to an incandescent, has been fifty to seventy-five percent, depending upon the number of LEDs involved in a particular lamp.

Most telling point is that over a two (2) to three (3) year period, I've seen a significant reduction in the electric bill, ~20%-25% in winter and ~30%-40% in summer.  That has made the conversion process more than financially attractive  :Thmbsup:.

Note:  I know more than I ever wanted to learn about this because of a stupid question I asked once in an electronics class  :'(.

Sarkand

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Re: Our experiences with LED light bulb replacements
« Reply #28 on: May 20, 2014, 07:42:54 PM »
I reiterate:  the heat in an electrical system is generated by resistance.  Wattage, voltage and amperage have nothing to do with it, except in how they influence resistance (push more of any of these into a medium of given resistance and more heat will be generated).  You can throw 10,000 watts at 100,000 volts across a superconducting wire or surface and generate little or no heat - resistance is reduced to near zero in such conditions.  At absolute zero, resistance of a conducting medium is zero, this is a law of physics - I haven't forgotten that much.  The heat is generated by the excitement of atoms unwilling to give up their electrons in order to propagate a current.  If the current is high enough, the wave is propagated - at the expense of the heat generated when the atoms are forced give up their electrons, as they have to be raised to a higher energy level in order to do so. In the trough of the current (wave), the atoms regain their lost electrons from the free electrons surrounding, ready to repeat the cycle at next crest.  At least that is how I understand it.

My question in fact relates to the mechanism by which the heat (resistance) is still generted at such high levels, even in conditions of lower wattage.  I still like my earlier guess of a step-down or AC/DC transformer.  These things produce heat like crazy - to get rid of the extra electrons, I expect.


CWuestefeld

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Re: Our experiences with LED light bulb replacements
« Reply #29 on: May 20, 2014, 09:03:01 PM »
the heat in an electrical system is generated by resistance.  Wattage, voltage and amperage have nothing to do with it, except in how they influence resistance

No, these are all parts of the same trinity.

VOLTS x (VOLTS/OHMS) = WATTS

We know volts is 110V. And rearranging the equation gives us

OHMS = VOLTS ^2 / WATTS

So given a constant voltage of 110, talking about Ohms and Watts are really just two sides of the same coin. You can't say they've got nothing to do with each other.

For a much better discussion, see http://amasci.com/elect/vwatt1.html. From that page (emphasis mine):

Quote
Conductive objects are always full of movable electric charges, and the overall motion of these charges is called an 'electric current.' Voltage can cause electric currents because a difference in voltage acts like a difference in pressure which pushes the conductors' own charges along. A conductor offers a certain amount of electrical resistance or "friction," and the friction against the flowing charges heats up the resistive object. The flow-rate of the moving charges is measured in Amperes. The transfer of electrical energy (as well as the rate of heat output) is measured in Watts. The electrical resistance is measured in Ohms. Amperes, Volts, Watts, and Ohms.

Renegade

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Re: Our experiences with LED light bulb replacements
« Reply #30 on: May 20, 2014, 09:15:55 PM »
Interesting development for LEDs:

http://www.cbc.ca/ne...-lightbulb-1.2648126

Quote
...
Radovanovic's lab at the University of Waterloo has used chemically-modified nanoparticles to tune LED light to a specific hue, rather than using expensive rare-earth elements to offset the natural blue, red or green light emitted by LEDs.
...
Slow Down Music - Where I commit thought crimes...

Freedom is the right to be wrong, not the right to do wrong. - John Diefenbaker

Sarkand

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Re: Our experiences with LED light bulb replacements
« Reply #31 on: May 20, 2014, 09:34:22 PM »
Excuse me, but this only reinforces my point.  Sliding the players around is only a different way of saying the same thing, that's the beauty of mathematics and physics.  Ohms do not equal watts, they are not two sides of the same coin, i.e., manifestations of one another, they have a relationship.  I have granted the influence of wattage on ohms - greater wattage given constant ohms will increase heat output.  Yes, heat can be measured in watts of power, but that heat is generated by resistance, and that's how thermodynamics works in Newtonian physics.                                                   

barney

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Re: Our experiences with LED light bulb replacements
« Reply #32 on: May 20, 2014, 11:07:50 PM »
Folk,

Several of you have made excellent theoretical points, and I understand the theories behind them to an extent.  However, none of those points are borne out by my electric bill reduction.  The realities kinda kill the theories in such discussions.  Financially, LEDs have altered my budget.  That is fact, and no theoretical discourse will alter it.

Sarkand

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Re: Our experiences with LED light bulb replacements
« Reply #33 on: May 21, 2014, 12:47:38 AM »
Folk,

Several of you have made excellent theoretical points, and I understand the theories behind them to an extent.  However, none of those points are borne out by my electric bill reduction.  The realities kinda kill the theories in such discussions.  Financially, LEDs have altered my budget.  That is fact, and no theoretical discourse will alter it.

Yep, ain't no doubt about it - LEDs will save energy, whatever the long-term costs in various applications.  That is important.  But we have let this thread go way off topic (mea maxima culpa, Mouser).  Mouser's stated primary motivation was heat reduction, however and wherever it is generated.  The cost of energy saved is gravy to him.  Unfortunately, he is now in the position of re-thinking his original assumptions, as am I.  The fact is that LEDs use less energy, that is important, and I intend to keep using them as the best alternative until something better comes along.  I am willing to pay the freight (still think it's cheaper).

mouser

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Re: Our experiences with LED light bulb replacements
« Reply #34 on: May 21, 2014, 05:40:28 AM »
There is no question whatsoever that LEDs use less electricity and will therefore save you on your monthly electricity bill.
Of course that still doesn't quite tell you whether you will make back your initial purchase price -- that will depend on how long you stick with your bulbs before upgrading; but given the high price of electricity it won't take long before you do.

As Sarkand says, the heated discussion here hasn't been about saving money, but about other issues involving LED bulbs -- most recently about the heat generated vs incandescent bulbs.

I have raised heat as an issue for two reasons: First, because I wish to reduce the heat added to the house by the bulbs during the summer, and second, because I wish to run brighter bulbs in light fixtures that are rated at 60w.

I think to sum up what we've sussed out:
  • The wattage of a bulb (whether it be incandescent or LED) is probably a very good measure of the heat being added to the environment; so an efficient 10 watt LED is going to be warming the room a lot less than a 60 watt incandescent bulb.  So far so good.  This addresses concern number one.
  • However, for some interesting and non-intuitive physics reasons, LED bulbs don't disperse their heat well -- and all of the heat they generate is located right at the base of the bulb (compare this to traditional incandescent bulbs which project heat out into the room along with the visible light) .  This is why LED bulbs have special heat sinks on them, and why many LED bulbs are listed as not for use in enclosed fixtures.  They generate much less heat, but all of that heat stays right at the base of the bulb.  Therefore, it may not be safe to run a much brighter LED in a fixture rated for 60w -- because the heat at the base of the LED may exceed the heat at the base of a 60w incandescent.
  • Heat generated at the base of LED bulbs has an additional consequence.  Not only because it might exceed the safe range for your fixture -- but because it can cause a very early failure of the bulb itself.  So pay attention to the quality of the heat sink on the LED bulb, and whether the bulb is rated for use inside an enclosed fixture.  Bottom line for concern #2: If it not enclosed and has a good heat sink, it's probably safe to use a brighter bulb in a fixture rated for 60w.

So, all things considered, LED bulbs do seem to still be a good solution to my concerns about heat and brightness -- with the caveats above.
« Last Edit: May 21, 2014, 05:56:46 AM by mouser »

xtabber

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Re: Our experiences with LED light bulb replacements
« Reply #35 on: May 21, 2014, 09:17:32 AM »
The Philips "lollipop" (as 40Hz dubbed it) design is supposed to provide an internal channel to circulate heat away from the base, allowing for a smaller heat sink, and thus a lighter and cheaper bulb.

mouser

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Re: Our experiences with LED light bulb replacements
« Reply #36 on: May 21, 2014, 09:28:09 AM »
Thanks for reminding me of one other thing you have to be wary of with LED bulbs -- they can be HEAVY.
I had to jerry-rig a special support for the bulbs in my kitchen ceiling fan.

mouser

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Re: Our experiences with LED light bulb replacements
« Reply #37 on: May 21, 2014, 12:17:29 PM »
This quote from CWuestefeld does a good job of explaining why i am moving to LEDs:
"Viewed another way, wiring up fifteen, hundred-watt incandescent bulbs is almost indistinguishable from a space heater.."

I do not want to be running a space heater in 100 degree weather.

mouser

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Re: Our experiences with LED light bulb replacements
« Reply #38 on: May 21, 2014, 12:21:39 PM »
Further reports -- The Cree 18w (100w equivalent) bulbs generate very nice light and are a no-brainer for my office.

However, my attempts to replace 6 candelabra bulbs in my dining room with LEDs has been a failure.  The bulbs in the chandelier point straight upward and all of the candelabra LEDS i have tried do a terrible job of casting light down.

So it looks like i'm stuck with incandescents in that fixture for now.

CWuestefeld

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Re: Our experiences with LED light bulb replacements
« Reply #39 on: May 21, 2014, 01:08:16 PM »
none of those points are borne out by my electric bill reduction.  The realities kinda kill the theories in such discussions.  Financially, LEDs have altered my budget.

I don't doubt you, but I'd like to feel out the specifics of it. My suspicion is that you might see a relevant difference in the warmer months, particularly when you're using air conditioning. This part is really easy to believe, because you'd otherwise be paying double for inefficiencies: once to run the heat-generating lights, and again to run the air conditioner to get rid of the waste heat.

But in the cooler months when you're running heat, this is much less clear to me. To a first approximation, I expect that inefficiency in the lighting is essentially free. That is, the waste heat thrown off by the lighting simply replaces the running of your furnace that would otherwise be generating that heat for you. The only loss in winter, then, would be a theoretical difference (that's probably not possible to realize for most of us due to the design of our HVAC system) in improved efficiency if you're using a heat pump for wintertime heat.

More simply: in the summer, inefficient lights bite you twice. But in the winter, I expect that inefficient lights simply allow you to run the furnace somewhat less.

mouser

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Re: Our experiences with LED light bulb replacements
« Reply #40 on: May 21, 2014, 01:10:16 PM »
Quote
But in the cooler months when you're running heat, this is much less clear to me. To a first approximation, I expect that inefficiency in the lighting is essentially free.

this is a good point -- though it might be less valid if you have a cheaper way of heating (wood, gas, etc.)

Shades

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Re: Our experiences with LED light bulb replacements
« Reply #41 on: May 22, 2014, 07:24:03 PM »
The design of LED lights is on purpose made to look like the light bulbs everybody knows. That way people are more easily persuaded to buy these. I think 2 or 3 design generations into the future will result in much more efficient shapes for LED light bulbs regarding heat, weight etc. But first the manufacturers need to make enough money to earn back their initial investments, to make it more interesting for them to continue with this type of lights. 

mouser

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Re: Our experiences with LED light bulb replacements
« Reply #42 on: May 23, 2014, 12:24:33 PM »
Another caveat i've found with replacing some of my incandescent bulbs is that even if you get an LED that is the same size as an A19 (standard bulb), sometimes the base is thicker which prevents it from screwing in all the way -- and thus will not power on.

Conclusion: Buy your LED bulbs from someplace where you can return them.

sazzen

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Re: Our experiences with LED light bulb replacements
« Reply #43 on: May 23, 2014, 02:56:09 PM »
I saw the title of the thread and got all excited, but nobody has addressed the issue that troubles me. I cannot SEE with these awful replacements.

Where I live, it has been almost impossible to find a 100W incandescent for several years. In any event, I knew the end was coming, and so I started experimenting with different bulbs. NOTHING comes close to the efficiency of the now outlawed lighting I have enjoyed all my life. 

My experience with LEDs has been even more disappointing than my experience with CFLs.  Because the little desk lamp in my computer room, with its tiny bulb, puts out such nice bright light, I expected the same from whatever LED I put in my reading lamps. But, no.  I cannot see. I read. I write, I work cross-word puzzles.  I sketch.  I paint my fingernails.  And, what will happen when those big round bulbs that light my bathroom die? How will I see to apply make-up?

I haunt Lowe’s lighting section. They are tired of me, and my questions, and my returns. Packaging may say “Replaces 100W incandescents” but for light output, that just isn’t so. I don’t care about heat. I don’t care about electrical usage. I don't care about life span. I just want illumination. 

For my reading lamps, which is what I really care about, 1600 lumens should work, but part of the problem is what Mouser said here: 
3. Spotlight effect.  The LED bulbs are more directional -- which can be especially troublesome for fixtures where the bulb is pointing up.

But I’ve also had noise and flicker from both CFLs and LEDs. Horrible, horrible, and no relief in sight. 








Shades

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Re: Our experiences with LED light bulb replacements
« Reply #44 on: May 23, 2014, 07:31:25 PM »
@Sazzen:
Perhaps you should consider halogene light?

When I have time, I'll drop by a light shop here in PY. They sell a led light fixture that is shaped like a construction light or flood-light (if that term makes more sense to you). The light surface would have a surface that has a similar size as the surface of an iPad. It's height would be similar to 3 iPads stacked on top of each other. The light is very bright and strong. It doesn't get that hot either. I don't know the type or model nr, so I'll ask. To me it looks like it uses a special type of LED, with a size and shape similar to a computer processor. 

Halogene light is something that should be easy to buy all over the world though. That type of light has quite a big range of color, so there should be something to your liking. However, they are not cheap (purchase and consumption) and don't last that long either. Having said that, their light I find much more pleasing than incandescents.

longrun

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Re: Our experiences with LED light bulb replacements
« Reply #45 on: June 05, 2014, 07:06:25 PM »
There's been some lame arguments that the reduction in power consumption from CFL bulbs results in less overall mercury being released into the environment in areas where coal-fired generators are the norm - because less coal (which also contains mercury) gets burned. But that sounds more like an industry thrashing around to find something - anything - to throw up against the fact that no level of mercury exposure is ever good for us.

I totally disagree. Less mercury is less mercury, and CFL's are easily recycled where I live.

barney

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Re: Our experiences with LED light bulb replacements
« Reply #46 on: June 05, 2014, 07:24:08 PM »
Been hunting for an LED light that can be used on [covered] front porch.  Needs to be reasonably weather resistant, if not weatherproof.  Also would be nice if it had built in light sensor so I don't have to remember to turn it on - or off! - but I might be reaching a bit there  :-\.  Corpus, while comfortable, is not a shopping metropolis  :tellme:, and I'm not having a great deal of luck searching online.  Any suggestions?

Stoic Joker

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Re: Our experiences with LED light bulb replacements
« Reply #47 on: June 05, 2014, 08:35:07 PM »
Been hunting for an LED light that can be used on [covered] front porch.  Needs to be reasonably weather resistant, if not weatherproof.  Also would be nice if it had built in light sensor so I don't have to remember to turn it on - or off! - but I might be reaching a bit there  :-\.  Corpus, while comfortable, is not a shopping metropolis  :tellme:, and I'm not having a great deal of luck searching online.  Any suggestions?

Lowes has a couple of variations on that theme that screw into the bulb socket, and then the bulb screws into them:
http://www.lowes.com...witch&facetInfo=
http://www.lowes.com...witch&facetInfo=
http://www.lowes.com...witch&facetInfo=
http://www.lowes.com...witch&facetInfo=
http://www.lowes.com...follow&cId=PDIO1
http://www.lowes.com...follow&cId=PDIO1

I've had similar motion sensitive widget on my front porch for the a few years now. Walk up, the light comes on. Walk away the light goes off in about 10 minutes. And the best part is, I do nothing. :)

IainB

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Re: Our experiences with LED light bulb replacements
« Reply #48 on: July 02, 2014, 08:58:39 AM »
Might be useful. Very informative notes here from Michael Herf - the guy who I gather is the author of f.lux (which I have used for a while now) and the original author of Picasa: - notes on Full Spectrum lighting.

mouser

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Re: Our experiences with LED light bulb replacements
« Reply #49 on: October 20, 2015, 05:07:10 PM »
Just reporting in that I'm still quite happy with my switch-over to LED bulbs.

A few observations thought:

1. I've had quite a few go bad.  CREE (manufacturer) replaced them though i had to pay shipping to send them the bad ones.  They seem to go bad in certain fixtures and not others.
2. I have a couple of Phillips ones that do a good job of lighting, but make a buzzing noise.  Very annoying.
3. Soft White is the only way to go, the cool temp bulbs get annoying very quickly.