LED Bulb Efficiency vs. Operating Life

I know it costs more to make a more efficient LED bulb for room lighting.  Is there also a tradeoff between efficiency and operating life?  I can't think of a mechanism, but I'm not so familiar with LED light bulb design. 

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Rick C.

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On 26.12.22 18:16, Ricky wrote:
> I know it costs more to make a more efficient LED bulb for room lighting.  Is there also a tradeoff between efficiency and operating life?  I can't think of a mechanism, but I'm not so familiar with LED light bulb design.
>
Lots of light, high chip temp, shorter chip life.

On Monday, December 26, 2022 at 1:49:14 PM UTC-5, Sjouke Burry wrote:
> On 26.12.22 18:16, Ricky wrote: 
> > I know it costs more to make a more efficient LED bulb for room lighting. Is there also a tradeoff between efficiency and operating life? I can't think of a mechanism, but I'm not so familiar with LED light bulb design. 
> >
> Lots of light, high chip temp, shorter chip life.

Don't they usually fail from the other electronics? 

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Rick C.

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On 12/26/22 13:13, Ricky wrote:
> On Monday, December 26, 2022 at 1:49:14 PM UTC-5, Sjouke Burry wrote:
>> On 26.12.22 18:16, Ricky wrote:
>>> I know it costs more to make a more efficient LED bulb for room lighting. Is there also a tradeoff between efficiency and operating life? I can't think of a mechanism, but I'm not so familiar with LED light bulb design.
>>>
>> Lots of light, high chip temp, shorter chip life.
> 
> Don't they usually fail from the other electronics?
> 
In the one I took apart all the LED modules were fine. The drive 
electronics failed.

On Mon, 26 Dec 2022 19:49:05 +0100, Sjouke Burry
<burrynulnulfour@ppllaanneett.nnll> wrote:

>On 26.12.22 18:16, Ricky wrote:
>> I know it costs more to make a more efficient LED bulb for room lighting.  Is there also a tradeoff between efficiency and operating life?  I can't think of a mechanism, but I'm not so familiar with LED light bulb design.
>>
>Lots of light, high chip temp, shorter chip life.

LED efficiency drops radically at high currents and high temps, and
LEDs degrade ditto. There is no tradeoff of efficiency vs reliability.
The real tradeoff is light vs cost.

For fun, blast an LED with freeze spray.

mandag den 26. december 2022 kl. 22.01.16 UTC+1 skrev John Larkin:
> On Mon, 26 Dec 2022 19:49:05 +0100, Sjouke Burry 
> <burrynu...@ppllaanneett.nnll> wrote: 
> 
> >On 26.12.22 18:16, Ricky wrote: 
> >> I know it costs more to make a more efficient LED bulb for room lighting. Is there also a tradeoff between efficiency and operating life? I can't think of a mechanism, but I'm not so familiar with LED light bulb design. 
> >> 
> >Lots of light, high chip temp, shorter chip life.
> LED efficiency drops radically at high currents and high temps, and 
> LEDs degrade ditto. There is no tradeoff of efficiency vs reliability. 
> The real tradeoff is light vs cost. 
> 
> For fun, blast an LED with freeze spray.

https://youtu.be/klaJqofCsu4

On a sunny day (Mon, 26 Dec 2022 11:13:38 -0800 (PST)) it happened Ricky
<gnuarm.deletethisbit@gmail.com> wrote in
<31902464-61b8-435c-ae71-178d9298c7f4n@googlegroups.com>:

>On Monday, December 26, 2022 at 1:49:14 PM UTC-5, Sjouke Burry wrote:
>> On 26.12.22 18:16, Ricky wrote: 
>> > I know it costs more to make a more efficient LED bulb for room lighting. Is there also a tradeoff between efficiency and
>> > operating life? I can't think of a mechanism, but I'm not so familiar with LED light bulb design. 
>> >
>> Lots of light, high chip temp, shorter chip life.
>
>Don't they usually fail from the other electronics? 

I have had several cheap China made LED bulbs fail
 http://panteltje.com/pub/LED_light_fix_IMG_6918.JPG
 http://panteltje.com/pub/LED_light_circuit_diagram_IMG_6925.JPG 
Whole row fails if one LED in a series row goes OC.
Probably on mains spikes as there is no switching regulator.

So it all depends on the circuit.

On 26/12/2022 21:01, John Larkin wrote:
> On Mon, 26 Dec 2022 19:49:05 +0100, Sjouke Burry
> <burrynulnulfour@ppllaanneett.nnll> wrote:
> 
>> On 26.12.22 18:16, Ricky wrote:
>>> I know it costs more to make a more efficient LED bulb for room lighting.  Is there also a tradeoff between efficiency and operating life?  I can't think of a mechanism, but I'm not so familiar with LED light bulb design.
>>>
>> Lots of light, high chip temp, shorter chip life.

I suspect that the limit is more on die surface brightness - too much 
and the phosphor life is compromised and it changes colour temperature.

Efficiency should make no difference provided that you choose a surface 
brightness than allows the phosphor to survive fr full working life.
> 
> LED efficiency drops radically at high currents and high temps, and
> LEDs degrade ditto. There is no tradeoff of efficiency vs reliability.
> The real tradeoff is light vs cost.
> 
> For fun, blast an LED with freeze spray.

Does that still work well with the modern high efficiency ones?

It used to be spectacular to dunk one of the 1970's red LEDs into LN2. 
They became incredibly bright as the crystal lattice stiffened up and 
resistive losses all but ceased. They tended to fail due to this abuse.

An old and a modern LED in series makes quite a good pop science demo.

-- 
Regards,
Martin Brown

tirsdag den 27. december 2022 kl. 14.49.21 UTC+1 skrev Martin Brown:
> On 26/12/2022 21:01, John Larkin wrote: 
> > On Mon, 26 Dec 2022 19:49:05 +0100, Sjouke Burry 
> > <burrynu...@ppllaanneett.nnll> wrote: 
> > 
> >> On 26.12.22 18:16, Ricky wrote: 
> >>> I know it costs more to make a more efficient LED bulb for room lighting. Is there also a tradeoff between efficiency and operating life? I can't think of a mechanism, but I'm not so familiar with LED light bulb design. 
> >>> 
> >> Lots of light, high chip temp, shorter chip life.
> I suspect that the limit is more on die surface brightness - too much 
> and the phosphor life is compromised and it changes colour temperature. 
> 
> Efficiency should make no difference provided that you choose a surface 
> brightness than allows the phosphor to survive fr full working life.

https://youtu.be/biEZ1TbdhhU?t=624

On 26/12/2022 17:16, Ricky wrote:
> I know it costs more to make a more efficient LED bulb for room
> lighting.  Is there also a tradeoff between efficiency and operating
> life?  I can't think of a mechanism, but I'm not so familiar with LED
> light bulb design.

If you push the blue light flux and/or residual heating high enough it 
can damage/darken the phosphor used to generate the yellow light.

The surface brightness of recent LEDs is now about the same per unit 
area as the sun - which makes it a bad idea to look directly at them.
Blue, violet or UV ones especially.


-- 
Regards,
Martin Brown