CREE Has Been Purchased New LEDs In The Works

Some cost in excess of $500 each. Unlit chips causing voids? All because someone's game playing. The laying out of a field of chips requires a host of design issues. It takes proofing thermally and electronically.

My 2013 Accord has LED headlights & I love 'em. Best headlights I've ever driven with. But I fear the day they fail because I'm sure the replacement will be pricey. But it's 8 years old & has 275,000 KM (well over half of that was night driving) & they still seem as bright as when new.

Will do. I was thinking aloud about the power supplies. I insist on Meanwell. The only complete unit I have encountered down here was a uni voltage 30 watt streetlight. Idiots connected a 120 vac unit to 240. Could not get the chips to fire isolated with 60 volts, and I did not like the heat sink (heavy but limited radiation area) so I chucked it.

What's a hoot is the number of new cars with LED stoplights with failed emitters. You can bet your rear end it's a problem with undersize heat sinking. Must replace entire lamp assembly. Six hundred and sixty dollars for a single Honda fixture. My 12 volt lamps contain just enough emitters to sustain bright light in series parallel @ 14 volts. Too much trouble for automakers.

I do not drive at night even in the city down here. But I wonder how long those mini fans last on LED headlamp modules? My beam pattern is set very low. plus I have a 18 watt spot, all aimed to spot speed bumps and potholes on city streets.

MEXICOWANDERER wrote:
Is this isolated to 120vac lamp + driver complete units? Sounds like the drivers are the fault. Overcurrent on the chips. I refuse to use anything but Meanwell drivers for 120vac. And my emitters are large enough to incorporate brushless dual ball bearing fans. I take the note about integrated lamps which I have never purchased.

I do not buy off-brand AC floodlamps. Only security lamps with a 15-second on time.

Well-built LED stadium floodlamps are hideously expensive. 3K for 1,000 watts consumed. In pallet lots.

Aluminum heat sinks that have been black hard anodized are ugly but yield 140% efficiency.

Doesn't matter if it was the driver or the LED, dead is dead and not coming back to life. Creates a bad reputation for the company name regardless when one stamps their company name on the product and it fails way before it should.

One would have though that the manufacturer of their own LEDs would at least choose carefully driver parameters which balance operation life vs brightness. There is trade offs that must happen, drive them at edge of absolute max light output and you get a much lower life.. Drive them even 10% under the max brightness and you will get extremely long life.. Works that way even with the driver circuit so that even applies here.

But just a word of warning, the LED lights whether just the chip or a complete bulb going forward will not have anything to do with the remaining Cree business units that where not sold off. So, just be careful when considering buying just on the name that is stamped on the LED product.

Is this isolated to 120vac lamp + driver complete units? Sounds like the drivers are the fault. Overcurrent on the chips. I refuse to use anything but Meanwell drivers for 120vac. And my emitters are large enough to incorporate brushless dual ball bearing fans. I take the note about integrated lamps which I have never purchased.

I do not buy off-brand AC floodlamps. Only security lamps with a 15-second on time.

Well-built LED stadium floodlamps are hideously expensive. 3K for 1,000 watts consumed. In pallet lots.

Aluminum heat sinks that have been black hard anodized are ugly but yield 140% efficiency.

MEXICOWANDERER wrote:

Were your lamps the entire structure CREE or just the emitters?

100% Fully built 120V Cree Par38 flood light light bulbs in retail pack with Cree name on the bulb and retail package.

100% Cree designed and built, bought specifically for the Cree name and reputation.

Bulb also had a aluminum finned "heat sink" right above the Edison base.. Replacements were sans the finned heatsink although I must say the replacements did last longer..

I was surprised to learn from a lighting industry rep a year or so ago that Cree fixtures were having issues with early lumen depreciation and worse, bad color shifting. They used to be at the top of the heap.

We redid the facade lighting on a prominent downtown high rise about 10 years ago with Cree fixtures. What was most impressive were the optics. The fixtures are mounted about 1.5 M from the wall & then wash down for about 25' for each row. The level of illumination is very nearly uniform from top to bottom. I drive by it 3 or 4 times a year at night & there have been no chip failures & color uniformity is still excellent.

Designing by conservative thermal limit in the P/N Junction is the only way to go in my book. There is of course an absolute limit. A massive or cooled heatsink leaves the thermal interface as the remaining point. I use Arctic Siver as the heatsink compound. Beryllium is better but toxic. CREE used to have the best thermal interface between the diode and substrate. But I am getting old and steadily losing contact with recent developments in the industry.

Were your lamps the entire structure CREE or just the emitters?

My beef with Cree is their success also caused severe damage to the brand name. Every Tom Dick and Harry on eBay, Amazon, elsewhere is happy to proclaim their products contain Cree LEDs. This is hardly the case, and is especially evident when your lighting gizmo quickly fails, while delivering a less than useful light quality (cri and temperature).

I build all my own LED lights whenever possible, and use almost exclusively Lumileds products, purchased via a secure supply chain, to avoid counterfeit products.

Wikipedia has a nice article on luminous efficacy, which also covers the limitations behind 300lm/w for "white" LEDs.

Brightness with Cree was fine, longevity is the problem.

Returned a couple of Cree lights back for warranty, the bulbs quit after less than a yr of use. Those lamps are in sheltered dusk to dawn open fixtures on a pole. So, if we assume 12 hrs per day of operation for 1 yr we get 730 hrs of operation which is as bad of life as the old fashion incandescent bulbs they replaced.. In reality, in dusk to dawn mode in my area the actual operation varies from 8-12 hrs from summer to winter making it look even worse.

Since the fixtures are on 15ft poles, it makes changing bulbs a real hassle and danger..

Wasn't very happy when they promise 10 or 20 yrs of life and they can't make even one yr of operation.

Collecting on said warranty was a joke, the shipping that I had to pay was nearly the same as what I paid for the bulbs!!! That should be a freebee BOTH WAYS.

I moved on, Amazon has a vendor called Hyperikon, A US manufacturer of LED lights although I doubt they manufacture the LED chips, they do seem to have a darn good life so far.. Have some fixtures using their 4ft T8 LED retrofit lights that so far has been in those fixtures going in 5 yrs!

Expensive? You bet but I am pleased with the life..

There is a fine life between light output and the life when it comes to LEDs, you can ramp up the brightness but reduce the overall life very easily.. From what I have seen, most manufacturers to get the max claim of brightness take the short cut of running the chips at the absolute max.. They are counting on folks to simply give up when the bulb dies and replace it with another without collecting on the warranty.

But as I mentioned, Cree themselves are dumping the LED business by selling it off, the purchasing company while they make it sound like they are a "manufacturing" company are in reality a Investor group that buys and carves out business units to eventually resell.

I have been through this myself having to live through a "carve out" more than once, it often ends up bad for the employees of the buyout, bad for the companies products because the buyer is only interested in maximizing their profits. Often the holding company will buy other similar unwanted company business units and put them together then sell them off for a greater profit.. All the while they scrape off huge profits that would normally go into R&D..