Reliability of LEDs: PF Members' Views and Experience

[CWatters]

Personally I'll never fit an incandescent or CFL again.

LEDs seem unreliable, and in "bulb" form in a lamp they don't diffuse through the lamp shade, they simply send a Bat Signal straight up at the ceiling.

I think you must have tried the wrong LEDs. I've had no issues with LEDs designed to replace incandescent bulbs in standard lamps, pendant light fittings or others with a shade.

Apart from a few early LEDs recessed down lights I've found them reliable. I currently have some unbranded LEDs in totally sealed fittings in the bathrooms. They have been in for several years now with no failures.

If you really must have an incandescent look at halogen... In the UK at least you can get a regular looking bulb that has a halogen bulb inside. Virtually identical performance to an old style incandescent but with the slightly improved efficiency of a halogen.

 

[sophiecentaur]

I've had better luck from CFLs, and I believe I had some that were dimmable, but I'd like to actually get light when I flip a switch and the CFLs barely illuminate until they brighten as they warm up.

They were a truly disgusting invention. In nearly every way, they are unsuitable. The illuminant colour is unbelievably bad the spectrum of any that I have seen has great gaps in it; no wonder they make people look ill. They are slow to warm up (even the later ones) and have short lifetimes. Also, they break easily.

If you really must have an incandescent look at halogen.

Still the nicest of all lights to have in the home - just expensive to run and not very long lasting. The point source of light is very attractive, too.
Once the LED quality settles down and customers get more discriminating, LEDS will be almost perfect. The almost continuous spectrum is very impressive.

 

[russ_watters]

I just had the first LED failure that I can remember, after several years running a couple dozen. I lost probably a dozen CFLs in the five years or so before that.

What I noticed that was frustrating about CFLs is they were all labeled "not for totally enclosed fixtures", which all of mine are. So I was basically required by law to use lamps that were incompatible with my fixtures. Annoying, but probably overall was worth it. LEDs have been better for me though.

 

[sophiecentaur]

I just had the first LED failure that I can remember, after several years running a couple dozen. I lost probably a dozen CFLs in the five years or so before that.

What I noticed that was frustrating about CFLs is they were all labeled "not for totally enclosed fixtures", which all of mine are. So I was basically required by law to use lamps that were incompatible with my fixtures. Annoying, but probably overall was worth it. LEDs have been better for me though.

I really would like to know what is going wrong in my houses (this one and the last one). They often die after a few days of flickering. If it truly is a thermal effect then there can be no excuse as the temperatures are not even hand-hot.
It could be due to mains voltage spikes then our mile-long overhead supply cable would be more susceptible than urban underground supplies - but the last house was well inside a town.
I like the pseudo-filament style bulbs (a-la carbon filament lamps of the 19th century) and they are all pretty expensive. I have had a couple of them fail after only a few months.
I guess I should find a way of logging mains volts and spikes, over a month or two. DIY or expensive off the shelf, I guess. Or I could just keep wingeing and wait for things to get better.

 

[arydberg]

We used to live near the beach. Many electrical appliances failed but the electrical company was no help. Finally a neighbor subscribed to a cable service. The serviceman refused to go up the pole until the wiring on the pole was corrected. Then the electrical company fixed the problem and all of our problems went away. in our case it was the salt air that corroded the wires.

 

[Baluncore]

I really would like to know what is going wrong in my houses (this one and the last one).

My filament lamps never failed in 10 years. They must have been very old lights because they were significantly red-shifted, well back towards the introduction of electricity. Then the power authority, as compensation for increasing demand in the valley, raised the voltage by moving up a few taps on the transformer that fed my road. Filament lamps could not handle the overly-increased voltage in expectation of more customers. I had no choice but to move, as my lease had expired.

My new location was purchased with a dedicated 11kV to 240V pole transformer. The voltage was OK, but in hot weather the lights would flicker and I had block periods of RF noise on the line. That noise was a real nuisance at antenna farm. The problem disappeared if I plugged in a load like a 2kW electric heater, so I fitted steep RF filters on my side of the power meters and put up with it. But the 11kV overhead lines still radiated phased spikes of RF all along the road, to the accompaniment of the wandering clicks of the district's electric stock fences, and the 19'th harmonic of the local LF air navigation beacon, very recently extinguished in favour of GPS.

Over a couple of months the line fuses to my transformer dropped several times, so the authority finally replaced the transformer. Turned out that, an internal nut on the 11 kV primary connection had not been tightened properly. That poor connection had arced and produced the voltage spikes that eventually took out the insulation. It was then RF quiet, and the newfangled CFL lights, (the early RF quieter ones, with the internal ballast transformer), did not flicker at all.

Power prices climbed, so cheap and noisy light-weight, (how much does light weigh?), switching CFL replaced all the older lamps. Then along came PV with grid tie inverters. Now the RF noise floor has grown like grass on the spectrum analysers, it is continuous in this world full of switching converters. During the same period, processor speeds have moved from 3MHz to 3GHz, and there are many more of them. There is now a certain and secure place for spread spectrum techniques and digital receiver technology.

At the moment, my PV keeps me slightly in credit, but the power authority plans to significantly drop the price they will pay for my excess PV energy next year. The network charge is greater than my power usage, so I guess the next change will be off-grid, to 12V DC LEDs, powered from PV and battery technology.

 

[NTL2009]

... It was then RF quiet, and the newfangled CFL lights, (the early RF quieter ones, with the internal ballast transformer), did not flicker at all. ...

I was reminded of those old not-so-compact-CFLs yesterday. I had to replace a couple of the last filament bulbs along my garage door and entrance - these lights are on a timer, ~ 6 hours a day average. I noticed that one of them was the old, original not-so-CFL. I'm sure I got two of them as a promotion from the utility, and I'm pretty sure it was back in the 1980's. It is still working (though it takes tens of seconds to come on, but no problem for these lights on a timer). I really can't say how many hours are on it, it may have sat in a closet for some years, and I don't recall when I put it in that fixture, but it could have been a few years ago to as much as 25 years ago. It;s mate died just a year or so ago.

They are big and heavy and poor light, and slow to come on - but they were built like tanks!

Oh, the reason I had some filament bulbs in was my old timer required a trickle current through the filaments to keep the clock alive (it worked in a 3-way switch set up, and they designed it so it would not need a neutral connection, in case one was not provided in the box) - so I needed at least one filament on the string to keep the clock active, the CFL or LED wouldn't do it. But I had to replace that 2 years ago, and the new one needed a neutral, which I was able to pull easily, so I'm good with all CFL/LED now (6 individual lamps). The new timer also adjusts to the seasons (enter your latitude zone) , so now I'm ON at dusk time, and OFF at midnight - nice.

edit - it looks like this one (I need to get on a ladder and unscrew 2 screws to get to it, so I'm going by memory - I'll take a picture when/if it burns out!)

 

[rootone]

Standard flourescent tubes have been around for a long time.
They just don't look very cool.
LEDs are now better than they used to be, and actually do last more than one year.

 

[anorlunda]

I think there should be a business opportunity for builders of new homes. They could include 12V or 24V DC for lighting only. It could be powered by a panel and and a battery, isolated from the grid, no rectifiers, wires run as twisted pairs, so that the DC would be extremely free from fluctuations. The light fixtures would be pleasant, versatile, low cost. very low energy consumption, and last nearly forever. They would stay lit during power blackouts. The homeowners would feel very green.

 

[jim hardy]

o I guess the next change will be off-grid, to 12V DC LEDs, powered from PV and battery technology.

That's where i'd go too. Propane for refrigeration heat and backup generator.

Right now I'm leaning toward 12V backup lights as anorlunda described for my guest house. A friend built his new home with such a 12V light and receptacle in every room . He could handle a months long power outage with just a lawnmower engine and automobile generator salvaged from discards.

 

[sophiecentaur]

I think there should be a business opportunity for builders of new homes. They could include 12V or 24V DC for lighting only. It could be powered by a panel and and a battery, isolated from the grid, no rectifiers, wires run as twisted pairs, so that the DC would be extremely free from fluctuations. The light fixtures would be pleasant, versatile, low cost. very low energy consumption, and last nearly forever. They would stay lit during power blackouts. The homeowners would feel very green.

The services are very reliable in the UK, compared with many other parts of the world and it would be hard to sell the idea to many people. The economics of PV are pretty marginal if you're not making use of the feed in tariff. I would think that you may just be able to sell a big UPS to UK consumers if it were only in lighting and central heating circuit (I mean the pump and controller) but that would only be for non-urban sites.
@anorlunda: your ideas about this may be coloured by your marine lifestyle - very attractive but not accessible for most of us.

 

[NTL2009]

I think there should be a business opportunity for builders of new homes. They could include 12V or 24V DC for lighting only. It could be powered by a panel and and a battery, isolated from the grid, no rectifiers, wires run as twisted pairs, so that the DC would be extremely free from fluctuations. The light fixtures would be pleasant, versatile, low cost. very low energy consumption, and last nearly forever. They would stay lit during power blackouts. The homeowners would feel very green.

Is there really much advantage? Doesn't an LED sourced with 12-24 VDC still need a switching circuit to convert that voltage to current? The switcher would be simpler with DC, since it would not need to store any energy between the AC cycles, and no flicker issues. But I'm not sure that would be worth the installation of a separate DC line. How much energy would be saved? Or do they just use a resistor to limit current (and waste energy)?

What I would like to see is, to have any new fixture or lamp fitted with the LED 'bulb' itself physically separate from the switcher/dimmer. That way, the heat of the LED would be kept away from the switcher, and as I understand it, heat is what kills the caps in the switcher and is a common failure mode. And providing caps rated for the higher temperature raises the cost of the unit. It would be nice to have standard components for this, maybe a third pin with a resistor that would tell the switcher the max current to apply, to support different wattage 'bulbs'?

 

[sophiecentaur]

Doesn't an LED sourced with 12-24 VDC still need a switching circuit to convert that voltage to current?

You refer to a transformer / voltage changer? That has to be done inside a mains voltage LED so having a low voltage distribution system would be virtually the same. Lengths of low voltage cable would (could) have 'significant' resistance and the bulbs could 'see each other' unless heavier wiring than strictly necessary were used. But a simple voltage regulator in each bulb could take care of that.
In fact, there is very little equipment in homes (outside of the kitchen / utilities areas) that actually use mains volts at all. There is good argument for changing the whole approach to electrical power in the home. The safety record of 'Wall Warts' (count how many there are in your living / media consuming /computing room) is not good and a proper central installation would be far safer.

 

[Baluncore]

LEDs can be connected in series to better utilise the available supply voltage. That often makes a linear current regulator a reasonable solution.

LEDs need a current regulator, not a voltage regulator. A switching current regulator is no more complex than a switching buck voltage regulator. There is no need for the on/off PWM brightness control that produces the strobe effect.

LED light output is temperature dependent, so it would be good to compensate the regulated LED current for temperature. It could also fold-back the current to protect the LEDs from high temperatures that reduce LED lifetime and reliability.

 

[anorlunda]

Doesn't an LED sourced with 12-24 VDC still need a switching circuit to convert that voltage to current?

No, that's not needed. There are at least 3 other ways.

1. There are DC-DC IC chips, all solid state.
2. There are also LEDs with built-in resistors for direct connection to 9V, 12V, 24V or more.
3. Put 4 LEDs in series to connect to 12V. I did that to convert light fixtures on my boat to LED, and they worked fine for 8 years.

You refer to a transformer / voltage changer? That has to be done inside a mains voltage LED so having a low voltage distribution system would be virtually the same.

No, you missed the point of my post, no AC-DC conversion necessary. I should have been clearer. I meant panel=solar panel.

t could be powered by a panel and and a battery, isolated from the grid, no rectifiers, wires run as twisted pairs, so that the DC would be extremely free from fluctuations.

 

[NTL2009]

No, that's not needed. There are at least 3 other ways.

1. There are DC-DC IC chips, all solid state.
2. There are also LEDs with built-in resistors for direct connection to 9V, 12V, 24V or more.
3. Put 4 LEDs in series to connect to 12V. I did that to convert light fixtures on my boat to LED, and they worked fine for 8 years.

No, you missed the point of my post, no AC-DC conversion necessary. I should have been clearer. I meant panel=solar panel.

A DC-DC IC is a switching converter, isn't it? At least for high efficiency, it is. As @Baluncore points out, if you use a series string of LEDS and get the Vf close to the supply voltage, there won't be much loss if you go with a linear regulator. But this moves in ~ 3.3 V steps, so for 12 V that's about 9.9V, and a 2.1V R drop, so a 17.5% added power lost in the series connection. Let's say 12 W of LEDs, so 1 amp, so 2.1 W loss in the R, for 14.1 W total. For a practical dimmer, you'd use a transistor/pot wired as a variable current source. The voltage would not change much, but the current would, so dissipation while dimming would be lower. Maybe that is an acceptable trade-off versus a switcher?

Connecting LEDS to a voltage source just isn't a good way to go, and not practical for large implementations. You cannot run them near maximum output,you will have batch-batch Vf variation, thermal variation, supply variation - if you run them to maximize light out, the voltage source will provide too much current when you hit the likely thermal runaway in some units.

You got away with it by using 4 LEDs in series rather than 3, so they are not running near their typical 3.3 V at their nominal current ratings. So you are running them at low current. So it works, but not really something that could be done commercially.

 

[anorlunda]

@NTL2009 , what about LED strips like in the picture below? I also used those on my boat.

I could cut them with scissors to have more or fewer LEDs in the strip. After cutting, I could still use both halves. I could feed the 12V from either end. The only thing on the circuit board besides the LEDs were the tiny chips about half the size of the LEDs with the number 212 on them. I assume they are linear current regulators, and they seem much too small to be switchers. Perhaps, the 212 are just resistors.

When making long-life KISS-principle lighting, I see no need to attempt to get maximum light out of each LED. It would be perfectly fine to get only 50% of max light and simply include twice as many LEDs.

Edit: Here is the https://www.ledwholesalers.com/v2/index.php?route=product/product&product_id=240&search=strip+12Vto those 12v strip lights. $2.50 for one strip, 20 LEDs per strip, only 3 watts for all 20 LEDs. I used 3 of them cut into 6 pieces in the cabin of my boat, providing me with plenty of light.

 

[NTL2009]

@anorlunda - The tiny chips are not active regulators, those are just resistors in those strip lights. 221 is 220 Ohms.

I have a similar strip, just 2x checked, and mine have a 150 Ohm R (marked 151) in series with three LEDS, and 300 LEDS per strip (100 groups of 3).

My 12V supply measured 11.76 when loaded down, 2.36V across the R, and 9.4 V across the 3 LEDS (3.16, 3.02 and 3.22), so about 20% power lost in the R. That may be an acceptable loss and trade-off for an R versus active circuitry. I've heard of people having problems trying to use these in a vehicle. The car battery will run ~ 14V when the alternator is kicking in, and that puts almost 2x the voltage across the R (the Vf on the LEDS won't change very much), so almost 4x the power dissipation on the R, and almost 2x the current for the LEDs.

My point was that in practice you can't reliably/practically run LEDs without some sort of current limit (even if it is just an R). You may be fine with running at low light and making it up with extra LEDS (we can get away with a lot on a one-off implementation), but a cost conscious producer, expecting to provide a consistent product, can't just throw 2x the LEDS at it.

The idea of running 12/24 VDC around the house is interesting. Most of our stuff that is plugged in the wall is low power. Looking around, the kitchen does use higher power stuff (toaster, counter-top u-Wave), and my wife uses a blow-dryer for her hair in the bathroom. Other than that, the vacuum cleaner ('Hoover' to some of you), but outlets in the hallways might be sufficient. Hmmm, then there is my "hi-fi" stereo - that's got a big-honkin' amp. SO I don't know, you still have to run power every where, and with the lower voltage, the wire size won't be that much smaller, then you still need some 120 V (North America) outlets - not sure it pans out in the end.

 

[jim hardy]

Looking around, the kitchen does use higher power stuff (toaster, counter-top u-Wave), and my wife uses a blow-dryer for her hair in the bathroom.

Indeed 10% of the 'things' consume 90% of the power. Some could be switched to gas , and the stereo could become a Class D amp .

Here's how son handles the toaster issue since moving to a boat -


a 1kw inverter would run the things you mention one at a time.

 

[NTL2009]

Hah-hah! I'll suggest that to my wife! I suppose that technique works to dry and style your hair too?

I was also thinking that for some of those things, a battery charged from the 12/24 V could drive a high power appliance for a short while. Still don't think it would catch on, but interesting to think about.

I've got a few smaller class-D switching audio amps. Really impressive what they can do in such a small package. I haven't looked into any hi-fi, high power beasts though, I think I'll look around.

Here's the two types I have - the smaller one to power some small bookshelf speakers for a small TV, and the larger one is hooked to some bigger stereo speakers on another TV, and to some small, but high quality speakers for a stereo in the bedroom.

https://www.amazon.com/dp/B0049P6OTI/?tag=pfamazon01-20

https://www.amazon.com/dp/B004JK8BDK/?tag=pfamazon01-20

 

[jim hardy]

Glad you approve of his technique.

I was also thinking that for some of those things, a battery charged from the 12/24 V could drive a high power appliance for a short while.

yes a big car cranking battery can deliver a kilowatt for a short while. A couple kw generator woouldn't be outrageously expensive if only run during high demand times and one arranged his household activities around the generator. That's easier for a single guy, though.

I must say this TI board looks interesting. 20 real watts is a lot of sound for a living room. Small enough to hide in something else..
https://www.adafruit.com/product/1752

 

[mheslep]

I see two electrical problems.

1, The environmental temperature. ...

This. The latest LED bulbs have a label, something like 'not suitable for enclosed light fixtures', or the reverse.

 

[anorlunda]

I just came across this video. It is instructive the way the guy speculated on failure causes, and how he tracked down the actual failure modes.

 

[Nik_2213]

In my experience, neither CFLs nor LEDs like the heat. Also, the more powerful the bulb, the shorter the life if ventilation is even slightly impaired.Sometimes you can switch designs to a 'skinny' type. Sometimes, you can adapt things. eg Here in UK, we have a zoo of Edison screw and traditional 'bayonet' fittings. ES, SES, BC, SBC etc. Faced with a light fitting that always ran hot and ate bulbs with grim regularity, I bought a BC/ES adaptor, switched to the other type of bulb. With the bulb now two inches further from its too-snug base, it runs sufficiently cooler to last much, much longer. Still, 'Due Care, Please' !

I'm not impressed by 'halogen in bulb' lamps. Although they give a brighter, bluer light, they do not last much longer than a standard incandescent. If you really want a long-lasting bulb, such as for some-where that is hard to access or essential for safety & cold-starts, consider incandescent 'rough service' types. They sacrifice efficiency for endurance...

Sometimes, you can combine different lamp-types in a multiple fitting. We have a tall stair-well where the lights fitting is really hard to reach, but essential for safety. Ordinary Incandescent lamps burned out too quickly, 'rough service' were too dim. CFLs took too long to strike in the cold, would flicker unpleasantly. Powerful LEDs died young. Worse, a family member had photo-sensitive epilepsy; any flicker was unacceptable...

Some lateral thinking produced a solution: I fitted two CFLs and a 'rough service' incandescent. The latter's prompt illumination masked the former's start-up flicker. As LEDs have improved, I've since replaced fading 'rough service' lamps with low-powered LEDs...

FWIW, I've begun replacing our suspended ceilings' 4-foot (1200mm) and 5-foot (1500mm) fluorescent tubes by their LED equivalents. Trial basis as yet, but they are slimmer, much safer to handle and give a nicer light temperature. Just remember to replace the fitting's 'blinky' starter with the 'bridge' device supplied !

I must agree with the comments that power spikes are a lamp-bane. I've fitted several plug-in spike-catchers around the house, the type with a tiny pilot-light warning if protection is active. They seem to help...

 

[anorlunda]

FWIW, I've begun replacing our suspended ceilings' 4-foot (1200mm) and 5-foot (1500mm) fluorescent tubes by their LED equivalents.

I also found the following video an hour ago. It may be helpful to you.



Heat may well be a factor. The interior space of a fluorescent ceiling fixture is very much larger than the interior of a bulb, so hopefully the LEDs will run cooler than in a bulb.

 

[sophiecentaur]

I skimmed through this thread again and I'm struck how, typically of Engineers, the replies were about reasons and possible workarounds. Why aren't you / we all totally disgusted about it and writing rude letters to suppliers? The prices of these devices are only justifiable if they actually last as long as the numbers written in the blurb. The public are being taken for a ride here.

 

[anorlunda]

I skimmed through this thread again and I'm struck how, typically of Engineers, the replies were about reasons and possible workarounds. Why aren't you / we all totally disgusted about it and writing rude letters to suppliers? The prices of these devices are only justifiable if they actually last as long as the numbers written in the blurb. The public are being taken for a ride here.

I did talk about prices and brand in #6. It's worth repeating. If you buy a brand name like Phillips, you're much safer.

You can't expect a company like IKEA to have the same kind of product engineering and testing as a company like Phillips. IKEA needs the flexibility to switch suppliers if necessary, and when switching they can't take a year or more to investigate and qualify a new supplier. They must depend on the statistics of customer complaints and returns to know when a product they sell is faulty.

LED bulbs at very low prices are sold in bulk on alibaba.com . I presume that they are bought by retailers who know next to nothing about the manufacturers.
Here's an example link to an alibaba ad for LED bulbs, €0,21 ($0.25) each in quantities of 60000 per day.. Use your own imagination to think of who buys them, and what names they stamp on them before sale.

 

[jim hardy]

Why aren't you / we all totally disgusted about it and writing rude letters to suppliers? The prices of these devices are only justifiable if they actually last as long as the numbers written in the blurb. The public are being taken for a ride here.

I think it's " the curse of the computer age" .

Windows has conditioned two generations that "workarounds", excuses and patches are the norm. Keyboard anonymity enables surreptitious and underhanded behaviors.
If societal values of excellence and virtue aren't dead they're on the critical list.
We need a Robert Pirsig revival .

[End Rant]

 

[russ_watters]

I skimmed through this thread again and I'm struck how, typically of Engineers, the replies were about reasons and possible workarounds. Why aren't you / we all totally disgusted about it and writing rude letters to suppliers? The prices of these devices are only justifiable if they actually last as long as the numbers written in the blurb. The public are being taken for a ride here.

This is far from the first thread on the subject - I suspect I started some myself. I've expressed disgust in the past, but I've never been a letter-writer. I don't know that it does much.

 

[russ_watters]

I just came across this video. It is instructive the way the guy speculated on failure causes, and how he tracked down the actual failure modes.

One open LED kills the whole string; I guess it is too much to ask that they be wired in parallel?

Heat hasn't seemed to be the issue with the LEDs whereas the CFLs I've lost have looked from the outside like they were overheated(discolored plastic). One thing I've done that seems to help is most totally enclosed fixtures have insulation on the top, inside surface. Ripping it off helps dissipate heat better.