In message .com,
writes
Being disappointed with LED light bulbs that did not last a single
month, I was looking for alternatives. I was surprised to find in the
website http://www.superbrightleds.com/MR16_specs.htm the following
warning:


"important note concerning the installation of LED products:

"Excessive heat will cause LEDs to fail prematurely.
"They must be operated in an ambient temperature,not exceeding room
temperature, for maximum life time.
"As the temperature rises above 23 degrees C, the life time goes down.

"Active cooling, such as a small fan, may be required if they are
installed in a small enclosed space without ventilation."


Since summer weather temperatures go way above 23 degrees Celsius
(73-74 degrees Farenheit) does this mean that LED light bulbs are
useful only as refrigerator lights or in air conditioned rooms?

I don't think this has anything to do with temperature at all since LED
lamps tend to run almost cold due to their very simple capacitive power
supply and low output. It's most likely that the problem that prompted
that company to put the warning up was just crap quality white LEDs
being used in their products. The first white LEDs from China had a
terrible failure rate due to the fact the technology was basically
copied badly and manufactured sloppily.

When their lamps started failing they probably made the assumption that
it was for the same reason that compact fluorescent lamps fail, and
blamed temperature.

As the Chinese get better at making white LEDs this should change for
the better.

About two years ago I purchased from the C. Crane Company a LED light
bulb indicated in their catalogue as item #20L. It contains 20 LEDs,
produces light equivalent to at least 25W incandescent bulb, and is
still functioning satisfactorily even though I did not take any
precautions whatsoever to keep it cool. Unfortunately, this model has
been discontinued, but the fact that the bulb survived summer
temperatures suggests to me that the technology for manufacturing LED
light bulbs tolerant to higher temperatures does exist.

I would appreciate it if someone here can recommend and provide
references for vendors selling 120V LED light bulbs with standard
household screw base connection, which produce light equivalent to 25W
incandescent bulbs or brighter and which can tolerate summer
temperatures.

I'm afraid it's down to trial and error. Even the best sources can get
a bad batch of LEDs, so even two lamps of the same style and brand could
have a different performance.

Another thing that fries LED lamps is people operating the 12v units on
electronic transformers which put out a much higher peak voltage due to
their pulsed operation.

--
Clive Mitchell
http:/www.bigclive.com