"A prize-winning light bulb that lasts for 20 years is going on sale in the US on Sunday - also known as Earth Day."
They're not joking:
"The first versions are set to cost $60 (£37)"
Who in their right mind will pay that? Idiots. Here's the kicker: 60 and 100W bulbs are banned, 40W will be banned in 2014. Will the price of the LED bulb come down to the price of indies by then?
Most would measure the life of such things in hours. Since they aren't usually on 24/7.
FWIW I've got several incandescent lamps which are more than 20 years old.
"It underwent18 months of testing".
So how do they know it will last 20 years?
Moved to our previous house in 1984 and there was a 150W clear incandescent in the garage, which looked as though it had been there for a while. Still going strong when we left in 2007.
The LEDs may last 20years, but the electrolytic capacitors in the power supply that drives them won't.
I'd be surprised if they did 10 years at the sort of temperatures they will be running at in a typical light fitting.
Andy.
En el artículo , ARWadsworth escribió:
They don't. It'll be a statistical assessment of probable lifetime based on the number of failures during that 18 month testing period. But as any fule kno, there's lies, damned lies, and statistics. The numbers can be massaged to give the desired result.
The acid test will be if they back up that 20 year claimed lifetime with a warranty of similar length, which of course they won't.
The same thing happened with CFLs, and the lifetime of those is nowhere near the claimed maximum (or if they don't fail, they dim so much as to become unusable.)
Although you can get 10 year no quibble warranties on some LED spot lights in this country. I seem to recall they are about £40.
I know. Progress is such a wonderful thing.
Why not? I wouldn't expect them to fail early from heat-related problems. I've got plenty of stuff 30 years old or more still running happily with the original electrolytics.
cheers
Jules
In most designs you arrange it so electrolytics are not near hot components, so extending life.
In a lightbulb you don't have that luxury, everything gets hot - 60 or 70 degrees - maybe even more in the confined space of a 12W lightbulb where the electronics is in the uppermost part of the bulb.
Most of the premature failures in LED (and CFL) light bulbs is due to ......... electrolytics drying out and failing.
Andy
Sure. But any half decent mathematician would be able to ask the pertinent questions that'll show up dodgy stats.
Dodgy stats are usually caused by people who are clever in their own field but know sod all about statistics. Have a look here:
on my brother's (now somewhat ancient) website for a good example.
It is quite similar to these:
Bet it ain't got a switched mode PSU though ;-)
Based on "accelerated life tests".
MBQ
I'd like to see such claims banned - unless backed up by a warranty.
One thing they don't simulate too well is electrolytic capacitor flaws.
Some paint technologists I know are waiting to see what happens with the Forth Rail Bridge now they have finished painting it with paint "guaranteed for 20 years". Very few of them think it will last.
It is one thing getting a paint system to work on clean prepared materials under lab conditions to pass accelerated ageing tests and quite another to do it on a large scale structure consisting of old rusty steelwork with sea spray, oil, rust and seagull dung liberally applied. Only time will tell who is right.
So which is it 25,000 hours or 25 years
as according to my calculations a year is 8,760 hours which means 25 years is 219,000 hours.
You'd also have to check what this warrebnty covers is it the LEDs or the whole product ?
Here here, in fact I think after buying =A330 or more for a 'bulb' that's garrebntied for life, then you return faulty ones to where you brought them and get a free replacement.
Then I wouldn;t mind paying =A330 every year for a bulb, if it failed every year and I got a free one back. Doubt the govenrment would sponser such a thing just ban working bulbs, and give MPs a generous light bulb allownce to cover it.
=A0 London SW
Indeed.
If there were any truth in that, most CFLs would fail by going flickery.
NT
As Rod says, they were starting to become common in equipment then (but 5 years earlier the picture would have been quite different, with meaty linear supplies everywhere).
cheers
Jules
Ordinary lightbulbs: don't need to be replaced very often and when they do it is not a significant expenditure. Fancy 'energy saving' bulbs, may last longer but at a price that gouges the domestic appliance budget rather than spare change. How many people stay in the same house with the same light fittings for 20years?
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