We buy the Walmart LED lightbulbs, the ones with the shortest life rating. (There are a few choices for life expectancy, and the price increases accordingly.) After a few months of use, several of these bulbs exhibit a flickering or a pulsing that is very annoying and forces me to change out these bulbs prematurely. The flickering or pulsing may vary between a steady flicker (pulse) to a random one and such throughout its use.
a) What is causing this? (Cheap electronic parts, I wager? An LED is a rectifier, as I recall, so that is reasonable to wager it is probably the source of the pulsing?)
b) Have other SDopers experienced with other brand LED bulbs, as well?
I have about 15 LEDs (incandescent or flood shape/style) in some track/can lights at work. They’re on for about 12 hours a day. Every few months one of them will start doing that. On for a few seconds, off for a few seconds. Sometimes it’s constant, sometimes it does it for a few minutes and then stops for a few hours.
My guess, and that’s all it is, is that the bulb or it’s circuitry is overheating due to the heat getting trapped in the can and either malfunctioning or it has a thermal fuse that’s opening then reclosing a few seconds later after it’s cooled off.
I’ve had a lot problems Ecosmart (only sold at home depot) and the one I just replaced a few days ago was “AcuityBrand”. I don’t recall if all the Ecosmart bulbs were ‘blinking’ of if some of them just stopped working, but they’ve all been garbage and have since been replaced by (mainly) Cree and GE.
That Acuity bulb must have been packaged box bearing the name of a major LED brand because I can’t recall every seeing an “AcutiyBrands” box and probably wouldn’t have bought it even if I had.
Being a store, our lights are on more then they’re off so longevity tends to be important. Not even just the cost but the constant ‘another bulb is out, I have to get to Home Depot in the next few days’ gets old. That has been one of the nice things about the [better] LEDs.
This is why it’s false economy to buy cheap junk.
I have a Cree 9W bulb that has been on for around 70,000 hours (8 years), and is still working perfectly. It probably cost me $13 at the time, but that’s only a little over $1/year and going down…
The phosphor used on some LED bulbs has emissions which decay very quickly. You can see this 60Hz strobing easily by waving your open fingers in front of the lamp. The chemicals in phosphors likely have different decay rates. When I see a bulb start to do this, I switch brands…
The trouble with LED bulbs is they don’t like heat. None of them, whereas incandescent bulbs love heat. LED bulbs of course don’t produce nearly as much, but that’s a problem in enclosed fixtures, and there’s a lot of enclosed fixtures around. That’s also a problem when you except to buy one for 25 cents (yes, I’ve seen four for a dollar at Walmart), and you know they’re using the cheapest possible components.
All electrolytic capacitors have a finite lifespan. Even less if they’re a cheap grade and/or exposed to a lot of heat like in an enclosed light bulb. Possibly even an enclosed fixture. The main purpose of the electrolytic capacitor is to smooth out power supply flickering.
I finally gave up on LED light bulbs inside my house. I have a lot of enclosed fixtures, I had a hard time finding ones that wouldn’t flicker when dimmed- even “dimmable ones”. They’d last only as long as an incandescent. A par 20 spot was used in an open fixture but failed and when I opened it up the circuit board was literally blackened from it’s own heat. I tried a pair of par 30 floods and they flickered horribly whenever the washing machine was on.
I agree the older stuff was great. I still have some older Cree lamps in outdoor fixtures, that run all night and where I don’t care about the inferior light quality compared to newer LEDs or incandescent.
In the summer of 2010 I purchased 3 LED bulbs at Home Depot. The lighting specialist. explained the differences cheap vs expensive. If I remember correctly Kelvin was associated with different ambiance of color?
Anyway I wanted the equivalent of three 100 watt bulbs, high quality, and to last as long as possible. I chose bright white for the kitchen. He suggested the daylight color option.
What was interesting was he removed one from the box and threw the bulb quite hard on the concrete floor. Then handed it to me and then my husband and told us to throw it as hard you can. We did!, a couple of times.
They were expensive! For 3 of them it was almost $70.00 with tax.
They had a seven year manufactures warranty or bring them back with the receipt and get a full refund. They are still working perfectly no blinking or nothing. I have purchased many more. What I did was purchase the best quality and longest warranty for where we used them a lot. Where they weren’t used as often I chose a lower quality. I’ve been very lucky and I’ve only had 3 or 4 burn out 11 years All of the bulbs were purchased in 2010.
Phillips, Echo Smart and 2 brands I’ve never heard of. I do not remember what brand is in the kitchen. They still work.
The answer is that all LED lights have a switch-mode power converter that steps mains voltage down to a few volts for the LED. One of the more expensive parts in this converter is a reservoir capacitor that has to withstand full mains voltage. To save a fraction of a penny these are often under-rated for ripple current so they overheat and their capacitance drifts downward, When this happens the typical response of the control chip is to cause flashing of the LED.
Not all. The filament-style LED bulbs have a bunch of LEDs in series, say 30-40, which together are close to line voltage. Then the driver circuit is a pretty simple current limiter.
I grew tired of the 4 foot fluorescent fixture in my laundry room. I made a neat looking four bulb retro fixture using three single 9 W LED bulbs from Walmart- I think they were four for nine dollars then. The fourth was from somewhere else. The thing worked, but it hummed relentlessly. One day I decided to diagnose it. Each Walmart bulb I unscrewed lessened the hum somewhat, but the other one didn’t. Replacing the three Wally World bulbs with three Dollar Tree LED bulbs fixed it.
I know people used to complain about CFL bulbs, but I filled all the sockets in my house with them when I moved in back in '04. They sure lasted as long as advertised. I felt kind of sad as I carried two plastic grocery bags full of them into Lowe’s to be recycled.
FWIW, I replaced over a hundred 4ft fluorescent bulbs with LEDs (with the same form factor as a standard 4 ft bulb) in my store. That was several years ago. These bulbs are running 12+ hours a day, some 24/7, and every one of them still works (including ones in coolers and freezers). I don’t know the brand off hand*, but they aren’t a ‘regular’ brand you can pick up at your local hardware store. I ordered them through my ‘light guy’. They were also quite a bit pricier, but they’ve paid for themselves both in energy savings and, probably more so, not having to replace ballasts on a regular basis.
*Looking through my old emails, they were Eiko brand. I don’t know the exact model, but they were these ones, possibly with slightly different specs. I wouldn’t hesitate to install more of them if needed (in fact, I put a bunch of them in my house/garage because I liked them so much).
We replaced nearly a hundred of those with only half as many LED tubes at our Masonic lodge a few years ago. In each four tube fixture there are now only two LED replacements, and they seem to be much brighter than the four tubes ever did.
LED lamps that have enough LED’s in series to run at near mains voltage should be more reliable because they don’t need a switched mode power supply. However, the failure point then becomes the LED’s themselves which don’t like heat and will be destroyed by heat over time.
The amount of light produced by an LED goes up with power but not proportionately. An LED will put out a reasonable amount of light and not too much heat when run at relatively low power. Maximising light output requires disproportionately high power and also produces disproportionate heat, which in turn minimises LED longevity.
The recipe for LED bulb longevity is therefore relatively simple. A bulb with fewer LEDs, each one run hard, will have a short life. A bulb with more LEDs, each run at a modest power level, will produce the same amount of light for less power and with less heat and will last far longer.
The real problem is that there is a market failure here. An LED bulb using more power and fewer LED’s will be cheap, but still last long enough that many consumers won’t notice the lack of longevity. An expensive LED bulb using less power and more LED will last for ages but many consumers will be put off by the high price.
This market failure is very clearly established by Philips “Dubai” bulbs. I haven’t checked the story from first-hand sources but my understanding is that the ruler of Dubai demanded that Phillips produce a well engineered long life LED bulb. Phillips did so but won’t sell them anywhere but Dubai. This can presumably only be because Phillips know that in the long term it isn’t as profitable for them to sell such long lasting bulbs.
What will be interesting is whether word of Dubai lamps spreads to an extent that either other countries take notice and start imposing similar economy/longevity requirements by law, or consumers hear of them and demand reaches the point where Philips (or others) start to sell them more widely.
I can see a time maybe in a couple of years where the legend of “Dubai Lamps” creates the latter situation. Nothing like unavailability to make people want something! And by selling them on the basis they meet “Dubai Standard” that might make them marketable despite the initial cost.
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