Customer Review

9 of 11 people found the following review helpful
1.0 out of 5 stars Good Light Quality but Unreliable, 4 Dec. 2010
Verified Purchase(What is this?)
This review is from: EDISON 6W Led GU10 Bulb 3x2W = 6w, Daylight White
(Beats 3w and 4w LED GU10 and CFL Fluorescent Energy-Saving GU10 Lamps)(deal only while stocks last)
I used some of these bulbs to replace 50W halogens above a kitchen work surface.

The 45 deg beam angle of these lamps gives a slightly more concentrated beam than the halogens I replaced which gave good illumination on the work surface (ceiling to work surface distance is 120cm). Intensity at the work surface is probably slightly brighter than for the halogens. These bulbs could also work well on a high ceiling for larger area illumination. They are less suitable if you want large area illumination from a lowish ceiling (the types of lamp using multiple LEDs on a flat surface without lenses work better for this).

The colour of the light approaches natural daylight without the excessive blue of some LEDs; colour rendering is good.

If the life predictions for these bulbs turn out to be valid they represent good value in the current LED market.

Update, July 2012
Unfortunately my experience indicates that these lamps may not meet the 50,000 hours average lifetime claimed for them; of 4 lamps I purchased one failed after about 18 months (and, after some discussion was replaced by the supplier) and a second one failed earlier this year. Estimated usage of these lamps was around 1,500 and 2,000 hrs respectively. Given the small number I bought it is impossible to say if I was unlucky and received parts from a bad batch or if there is a more general problem. The supplier stated that their experience indicates only 1 in 1000 early failures (putting the chance of two early failures at a million to one).

Further Update Aug 2012
I performed some analysis on the 2 failed lamps - it turned out that both were caused by failure of an LED (not the power circuitry). The LEDs are in series so if one fails they all go out. By taking a good LED from one of the failed lamps and replacing the failed one in the 2nd lamp it started working again but failed again after a few weeks.

I then pulled a sample LED apart to look at its construction; there is a dome shaped lens directly in contact with the LED chip which is made of a silicone elastomer. The elastomer also encapsulates the very fine wires connecting the chip to the solder terminals. Silicone has a high expansion coefficient; work done in the early 80s on the packaging of silicon chips established that silicone elastomers cannot reliably protect chips if the wire bonds are covered (work reported by Bell Labs and others). As the assembly heats and cools when it is switched on and off the fine wires are repeatedly stressed by the expansion and contraction of the silicone until they eventually break. I think it is likely that the flashing behaviour which I and some other reviewers have seen is indicative of this failure mode: the silicone causes a break in the wire when it heats up; after the contact is broken the silicone cools and contracts and the wire makes contact again - and so on. The wires are usually gold which is a very ductile metal so they can withstand being stressed repeatedly for a while - but eventually break.

It is likely that the life of these lamps will be much more dependent on how often they are switched on and off than total hours running time.

On the basis of this new information I now consider these lamps a definite 'don't buy' and have revised my rating to 1 star.
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