7W AC bulb teardown in EDN mag.

[Dave_H]

Interesting acticle in EDN magazine (March 18 2010) on tear-down
of the Tess 7W AC LED bulb, with nice photos:

http://www.edn.com/article/CA6722379.html?text=tear-down

Dave

 

[blasterman]

So, now we're abusing LED bulbs so badly that they only last 10,000hours?

Like somebody said in the comment section, if the life span on the bulb is that low due to such poor thermal management, then the LEDs won't be running at an optimum lumen out-put for a significant portion of that 10k predicted hours.

They cost over $20, an it will take 3-4 of them to match a single CFL. Nah. Just more fodder for the 'LEDs aren't there yet because dept stores don't sell them' crowd.

 

[Dave_H]

Yah, I'm not rushing out to buy any. The 10k hours strikes
me as low. Also on the vendor website it's claimed their 10W/
1000-lumen bulb replaces 100W incan; not likely, I consider
a good regular 100W as 1500-1600 lumens typically.

Interesting at least to see the construction technique,
which is not unreasonable. However as you're heavy into
custom lighting, your comments are no surprise.

BTW, looking at some Nichia datasheets, saw some that
are apparently well-spec'ed but only rated 1000h lifetime...
obviously for flashlight use. LEDs themselves could have
something to do with low lifetime, not just poor thermal
management.

Dave

 

[blasterman]

I consider a good regular 100W as 1500-1600 lumens typically.

Remember that it only takes about 400 lumens of bare LED to match the radial out-put of a 100 watt incan. That's because the LEDs are directing their light in a ~120 degree circle, while the incan is measured at 360 degrees. So, the LEDs have about 4x advantage....and the marketing guys take full advantage of this. With a 10k hour life though you'd think 1watt warm-white LEDs would start color shifting rather soon.

I'm always interested in how new LEDs are applied in fixed lighting, but I'm bothered by two trends first. First, we're seeing power LEDs in an increasing role as disposable because of the thermal issues.... due to trying to cram them into a dead light-bulb format. Next, with all the resources Asian manufacturers have you'd think by now the'd come up with something innovative rather than more of the same.

At some point soon due to political pressure Asian currencies are going to start climbing against the dollar, and this is going to make this stuff more expensive rather quickly.

 

[jtr1962]

So, now we're abusing LED bulbs so badly that they only last 10,000hours?

Ever consider that this is totally intentional on the part of LED screw-base manufacturers? In the push to get outputs which rival CFLs or incandescents, manufacturers have found that excess heat works to their advantage in the guise of much shorter LED life. Not good for the consumer, obviously, but great if you're in the business of selling light bulbs. With a 10,000 hour life, assuming 6 hours of use per day, your consumer will have to replace that expensive LED bulb about every 5 years. Now consider the alternative of running LEDs at temperatures where they really do last 100,000 hours. You're basically in a situation where the consumer buys the bulb once, and that's it, although with heavy use they might replace it every 20-25 years. I'm not saying I agree with this reasoning, only that I understand it from a business standpoint. Of course, you can justify charging somewhat more for that 100,000 hour LED bulb, so maybe there's hope yet for a sustainable business model which lets manufacturers sell LED products ( both bulbs and fixtures ) which take advantage of LED's lifetime potential.

And BTW, I personally think we should aim for 200K, 300K, even half a million hours in LED products. They should be something which not only lasts your lifetime, but the lifetime of the building they're in.

 

[blasterman]

Ever consider that this is totally intentional on the part of LED screw-base manufacturers?

Yep :tinfoil:

The sad thing is that consumers will actually buy this crap without doing the math. Plus, the color will likely shift for the later half of it's lifespan. We then get the usual mouth breathers in this forum using it as justification for their luddite campaign against better lighting technology because Asian manufacturers are flooding discount stores with junk electronics.

It's the same arguement I made in the "Designed Obsolescence" thread, but don't want to take away from Dave H's enthusiasm for wanting to dissect these products.

All my fixtures I hock together I plan on getting at least 100k hours out of.