Electronics > Repair

Why/how do these LED lamps fail so fast?

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coppice:
Has anyone seen screw in or bayonet LED bulbs that are rated for use in an enclosed or semi-enclosed luminaire? For both CFL and LED bulbs the life has a lot to do with their running temperature, which can be changed a lot by the air flow. CFLs go downhill several times as quickly with the restricted air flow in an enclosed luminaire, but look so ugly out in the open. LEDs seem to be similar. I wonder how the average life of luminaires with integrated LEDs, that have some space to breath, compare with bulbs that can get pretty hot, even without restricting their air flow.

floobydust:
I haven't and doubt they exist for the reason below. There's screw-in but no bayonet bulbs aside from old automotive this side of the Atlantic.

I say the main reason LED bulbs are crap is because of the sea of patents particularly on heatsink design.
So getting convective cooling in an enclosed fixture, it can't be done, legally. Cree has the patents for heatsink fins, along with related litigation with Feit etc. 
Meanwhile, households get smooth body bulbs that can't expel the required heat.

I just replaced a bunch of Ecosmart bulbs (enclosed fixtures), Home Depot/Walmart pretty low quality and they run very hot. Maybe 12-18 months life.
Autopsy showed the plastic body had cracked in two, 130°C rated 15uF Aishi cap seems worn at 10uF plastic wrap cooked and linear IC seems to have issues. They just sit there very dim. LED's look OK.
10 years ago Ecosmart were smoking and burning, a few fires so those were recalled 554,000 bulbs. Interestingly, they had fins and design house "Lighting Science Group" did EcoSmart, Sylvania, Westinghouse and Definity.
So you see the problem with one design being flawed and many brands get affected. Or the skirting the patent issue, there is massive litigation still going on.

IanB:

--- Quote from: coppice on November 24, 2024, 06:07:12 pm ---Has anyone seen screw in or bayonet LED bulbs that are rated for use in an enclosed or semi-enclosed luminaire? For both CFL and LED bulbs the life has a lot to do with their running temperature, which can be changed a lot by the air flow. CFLs go downhill several times as quickly with the restricted air flow in an enclosed luminaire, but look so ugly out in the open. LEDs seem to be similar. I wonder how the average life of luminaires with integrated LEDs, that have some space to breath, compare with bulbs that can get pretty hot, even without restricting their air flow.

--- End quote ---

Try looking at filament design LED bulbs like, for example, the Philips Ultra Definition kind. In these bulbs most of the heat is dissipated by the filaments, and less by the electronics in the base. The bulb itself does get warm over time, but it never gets hot to the touch. If you run them on a dimmer they get even less warm.

floobydust:
Isn't that the worst possible configuration for getting rid of heat?
The filament in free space, enclosed in the bulb. Dissipate 5-12W? With tungsten, yeah but I'm not an optimist.
It might be as you say that these filament bulbs have no LED driver, just the series string so a bit less heat.
"...average life of 15,000 hours/13.7 years... 3 year warranty" (Feit)
Mainly radiation and a little conduction heat transfer on the one end.

"Feit Electric announced that it owns a set of patents directed to covering the yellow material used on LED filaments." against GE and against Ledvance LLC etc.

It must be some high temp material  :-//

Feit Electric Announces First Patent Enforcement Action Against Infringing White LED Filaments

Then Seoul Semiconductor (sold under Philips name) and Seoul Viosys are suing Feit again.



All this litigation just costs us, it gets added onto the bulb price and circumventing a patent usually means compromise ala hot running short life for other manufacturer's offerings.

cosmicray:

--- Quote from: floobydust on November 24, 2024, 08:47:14 pm ---Isn't that the worst possible configuration for getting rid of heat?
The filament in free space, enclosed in the bulb. Dissipate 5-12W? With tungsten, yeah but I'm not an optimist.
It might be as you say that these filament bulbs have no LED driver, just the series string so a bit less heat.
"...average life of 15,000 hours/13.7 years... 3 year warranty" (Feit)
Mainly radiation and a little conduction heat transfer on the one end.
--- End quote ---

For incandescent bulbs, base down is best for heat convection (because the filament is where the heat is). For LED bulbs (with the one side PCB backed with aluminum), base up is better (because otherwise you are using the heat to slowly cook the LEDs/electronics). Sealing everything in a constricted air space is probably bad for both types.

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