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LED light bulbs how long should they last - 3 blown in 24 hours!

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Got lots of Crompton and Tigra(?) LED bulbs where the LED filament is shown in warm white around 5-7.5W, yet 3 of them blew in 36 hours.

 

Anyone else experiencing LED bulbs blowing? 

 

The blown bulbs, flashed on and off for a minute or so at about 2 Hz before giving up.  Switching on and off does not 'reboot' them.  Leaving the blown bulbs on and the bases remain warm (as if the power converter is still running).

Note bulbs all blown at night (so can't blame my solar installation I reckon)

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Yup, I've experienced this! Bought a load of Phillips reduced at homebase. Two are already gone! Thought it was just me! 

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I get 10000 hours out of mine

NOT I’ve purchased from Four different places None seem to last 

I’ve an electrician friend who has the same issue He tells me that a cheapy box full from Wickes has proved to be the best so far

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Yes they are disappointing so far.

 

Not had reliability issues but the light output and colour difference from lamps claiming to be the same power and colour is disappointing.  Making me think the only way to to get a roomfull to look right is buy a bulk lot from one manufacturer so you have identical spares for a very long time.

 

In the old days any make of 60W GLS looked the same.   :(

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14 minutes ago, ProDave said:

Yes they are disappointing so far.

 

Not had reliability issues but the light output and colour difference from lamps claiming to be the same power and colour is disappointing.  Making me think the only way to to get a roomfull to look right is buy a bulk lot from one manufacturer so you have identical spares for a very long time.

 

In the old days any make of 60W GLS looked the same.   :(

^ This. Bought 3 matching bulbs for a set of 3 pendants, no cheap (BEL from Edwardes?) and one blew after a short period. Replacements are both a different shape/size and different colour.

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There's a thread somewhere where I looked at this, might be on the GBF, as it was ages ago.  I conducted several "post mortems" on blown LEDs and in every single case the LED itself was fine, it was the driver circuit in the base that had failed, always through obvious overheating. 

 

The smaller the lamp, the greater the failure rate for mains powered LEDs.

 

What I have found is that 12 V LEDs are very reliable.  I've had no failures at all running them on proper DC supplies, and we have loads of them.  I did have a lot of early failures when using 12 V LED downlights, and traced the cause of this to the bridge rectifier in the 12 V MR16 failing.  Every single failure was a bridge rectifier failure.

 

After a bit of investigation, I discovered than the small 12 V "transformers" for downlighters had an output that was 12 VAC at around 20 kHz.  The MR16 12 V downlighter design was originally intended to run on 12 VAC at mains frequency, 50 Hz.  What was happening was that at 20 kHz the bridge rectifiers in the LEDs were just too slow, as they did not use fast recovery diodes.  The result was overheating and failure.  Replacing the downlighter "transformers" with proper 12 VDC supplies completely cured the problem and resulted in all the MR16 downlighter LEDs running a great deal cooler, too.  Almost all the heat was coming from diode losses in the small bridge rectifiers, that were really struggling to work at the 20 kHz coming out from the standard miniature downlighter "transformers". 

 

I should add that these small "transformers" are absolutely fine with 12 VAC tungsten MR16 bulbs, the problem was purely with LEDs.

 

One tip is to see if any LEDs are getting warm and where the heat is coming from.  If the LED base is getting hot, then you can expect the LED to fail sooner or later when the driver burns out.  There are a LOT of fake marked, far-Eastern made, 230 VAC LEDs around that are not approved to any acceptable safety standard and it's really hard to tell which are the decent ones and which are not.  It seems even some of the big name brands have been caught with fake components, so even the name is no sure-fire guarantee that the lamps are approved and will be reliable.

 

Some types of 230 VAC lamps are inherently more reliable by design.  For example, the ones that have what look like fake filaments use a series string of LEDs that operate at high voltage, so they often just have a simple rectifier and capacitive voltage dropper in the base to limit the current.  These tend to run cool, as they have no dodgy switched mode driver squeezed into the base.  There are also some conventional size 230 VAC lamps around that use long chains of LEDs in series behind a diffuser and similarly they have no switched mode driver in the base and tend to run cooler and may well be more reliable.

Edited by JSHarris
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^ I'll add to that if you do have MR16s that have failed on an AC supply, chances are that replacing the  PSU with a DC one  and then  *reversing* any that still don't light in their sockets could well be a money saver, as I've never seen an internal rectifier fail completely, just in one direction...

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The Megaman LED GU10's have a 5 year warranty. BUT, they wont warrant them for that long if they're in a fire rated downlight! Hmmm that will be most scenarios then! I find they last a couple of years, some have lasted longer.

 

Its actually the reason I've gone for standard GU10 downlight fittings in the new build. These "all in one" fittings are great until you cant get them any more and from everyone I've spoken too failures are common even with the expensive brands.

 

 

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The reason they won't guarantee them in a fire rated downlighter is heat build up, I suspect.  I think it's now pretty clear that heat at the base of the lamp, where the driver circuit is (literally) squeezed in, is a major cause of early failure.

 

My advice would be to not use GU10 230 VAC downlighters, but use MR16 12 VDC ones and then run them from a 12 VDC supply.  Not only will the efficiency be better, but there will be little heat in the lamps and the reliability when used in fire rated downlighters may well be no different to that when used in any other fitting.

 

MR16 and GU10 share the same diameter of lamp at the front, so it may well be possible to convert a GU10 fitting to an MR16 fitting, just by changing the internal lamp fitting and adding a 12 VDC power supply to run them all.  The wiring will be fine, usually, as unless you're running dozens of the things the voltage drop on the cable will be modest.

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I replaced about 60 GU10 recessed 240V downlighters with the LED version from Ikea (approx 4W) in 2013, and I think only about 1 or 2 have gone since.

 

Another data point.

 

The exercise cost around £250 so they had better last...

 

Ferdinand

Edited by Ferdinand

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I replaced about 45 low Voltage GU10  in downlighters in 2014. One went almost immediately and was replaced by the supplier. None have gone since.

Edited by HerbJ

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I replaced all the bulbs in two properties with the cheap LAP units from screwfix a year ago (40+ Bulbs). So far they're all still working, and I've had no problems with colour match between batches. Currently selling for £1.50ish each.

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I've found the same with the Screwfix ones, and interestingly they don't run hot, either, so I strongly suspect that they do not have a driver in the base.  I swapped one over recently and the base was pretty cool, which suggests that they may well use a long series chain of LEDs with a capacitive dropper.  I have a few spare and may well take one apart just out of curiosity.

 

 

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Looking closely I can actually see the long LED filament has blown - on this Crompton bulb the brightness increased and then it went out altogether a few seconds later

 

Chasing supplier now

IMG_20180113_093019.jpg

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