Quick post this. In the Incandescent Era, the replacing of light bulbs was expected & understood - metal glowing white-hot for months on end, could only be expected to end in a flash, right? Then along came LED bulbs, whose longevity & efficiency, we were assured would deliver us from perpetual bulb-changing.
Well, it appears that the Aldi & Lidl supermarkets around here didn't get the memo, cos' they keep flogging crap to me. I bought & installed a handful of lightbulbs about a year ago, and in the past month, have had three of them fail, all within days of one another. The cynic in me suggests that it's more likely to be a case of 'planned obsolescence' than the Bulb-god calling his children home. They're not running hot either, the usual excuse that's trotted out. So how can a bulb just warm to the touch, not last much longer then an incandescent that you could cook your dinner on?
But for the fact that I possess an LED bulb that was bought 10-12 years ago, I'd be inclined to take their claimed longevity as a whole, with a pinch of salt. [Edit: I tell a lie, just recalled and photo-snapped a second ancient but-still-working LED bulb that's in my possession, and interestingly, both use identical LEDs]. Nevertheless, lots of the claims made by LED bulb manufacturers, rarely seem to be borne out in practice, in my experience anyway.
Below are pics of the batch of Lidl bulbs that I bought, and that are failing as if to order. Included as well is a pic[s] of the only [2] Chinese bulb[s], out of about a dozen, all from different manufacturers, that I got 10+ years ago. The first has been running 6-10 hours, day in & day out, since I bought it. The other, a low-lumens affair, also produces that horrible white-light, so has seen more limited usage - yet still orders of magnitude more than the 'Livarnolux' crap that Aldi/Lidl sold to me.
Edit1:
With 3 blown bulbs knocking about & time to kill, I decided that a little investigatory work to determine the nature of the failures might be in order. Although the symptoms leading up to each bulbs demise weren't identical, I figured that each must have had a common thread. The first oddity I came across was that although physically identical, one of the bulbs weighed over THREE times that of the others (see pic) - so, being the piggy in the middle, marked it out as the first victim. [Oops, though all are made by Livarnolux, and look identical, this one has a different model number. It is also rated at 12W, the others are 9.5W].
Removing the globe itself was trivial, getting at its entrails proved anything but. First discovery was that the LED's themselves appeared to be in perfect condition - this was always the weakest link in all of the half-dozen or so LED bulbs I've tried repairing in the past, the burned-out LED normally being easily discernible.
With the LED module removed, the source of the extra weight was apparent - a big hunk of metal, clearly meant as a means of removing excess heat from the LED's. This also suggests that this 'version_2-kludge' was an attempt to rectify a problem with a prior version - one that obviously failed! But what they lacked in competence, they made up for in craftiness, attempting to ensure that no one else could fix it either - by encasing the entirety of the electronics in soft plastic!!! (see pic).
Needless to say, removing it proved a real chore, first, just getting the PCB from the bulb's plastic housing without breaking stuff, next, having to chip away at the 'sarcophagus' encasing the electronics, and all without damaging components. But endeavour to persevere I did, and after about 2 hours, had something that I could at least attempt fault-finding on.
It didn't take long to trouble-shoot either, seeing as there's not that many components involved. It turned out to be that an electrolytic capacitor had failed - 22uF in name only, was now just 4-and-change. Replacing this with something half-way similar, had it up and running again (see pic).
Of course, there's no putting the genie back in the bottle with this bulb, as I damn near had to destroy it to 'fix' it. Note above that the measurements were made with only 60VAC applied. This was partly because that was blinding enough, and partly because the electrolytic I replaced was rated at 50v versus the 63v of the blown one. And also, when I wound it up to 100VAC for more than 10 seconds, something started to smoke - always a bad sign! [Hmmm, further tinkering revealed that the 'smoke' was a result of the circuit hitting a 'dis-resonance' of sorts at specific voltages. Increasing the AC voltage gradually via the auto-transformer as I did, above 60v, the current would increase rapidly, causing a current-limiting resistor to whimper. However, jack the voltage right up above the 'un-sweet spot', or even straight to 240v mains potential, and everything ends up smelling of roses, the circuit being perfectly behaved (see pic). Measured efficiency is only 75% for this 12w bulb - that's a whole 3 watts going abegging. I'd have expected better from a deliberately expendable design such as this].
With the failure of an electrolytic in a LED bulb, it gets you thinking. By their very makeup, electrolytic capacitors WILL fail in time, it's guaranteed. Google throws up numbers, that between 1,000 & 10,000 hours use, you should expect failure. There is no way any of my blown bulbs had 10,000 hours of use. I doubt the longest-lived had more than 5,000 hours, and I'm sure that one had less than 1,000 hours of light use. And when they fail, it's not the LEDs that die, it's a shitty component that the text books will cheerfully tell you, is bound to fail! Were they to use tantalum capacitors, Google talks about them lasting 20+ years. Which will never happen, not in the 'throw-away society' we live in. It just grinds my gears that a consumer item with fractional energy bills, is deliberately designed to last no longer than the incandescents it replaced.
Edit2:
Having some time to kill, I decided to investigate another of my dead Aldi/Lidl bulbs.
Though the failed bulbs may look identical, this one shows that they are anything but. This design screams 'CHEEAAAPPPP', a bean-counter's wet-dream - there's almost nothing in it!!!
On the one hand, there's elegance in its simplicity. The PCB is comprised of a current-limiting resistor, a bridge-rectifier and a reservoir capacitor, that's it! This high voltage DC (300V approx) is applied directly to the equally-simple LED panel, made up of LEDs, a current regulating I.C, and a handful of resistors. All of the LEDs are paired, connected in parallel, then each successive pair connected in series. Given that 300VDC is powering this string of LEDs, they are atypical LEDs, having large voltage drops, which curiously, are not the same - the first LED-pair's voltage-drop is around 15v, the next pair in the string is around 30v, which continues similarly to the end of the string.
This is also the Achilles heel of the bulb - one faulty LED-pair and you're in the dark! Although none of the LEDs are visibly damaged, when I apply the turn-on voltage to some of the pairs, their brightness changes erratically. I guess designing LEDs with such high voltage-drops is still in the development stage!
On the other hand, there's nothing fixable with a design such as this. The other bulb pictured above is a delight in comparison. Hell, this bulb has only half the LEDs, but the same Lumens-rating. True, it has a marginally lower power-rating (9.5W versus 12W) but the LEDs must still run much hotter, especially when you consider how flimsy the aluminum heat-sink used is - one-third the weight, remember!!!
I'm not surprised that a version_2 was called for.
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