Mike said:
That's an interesting piece of information. So... is it in terms of light
output that they fall short? That would be my expectation.
Well, first and foremost the fact that a lamp designed around an
incandescent filament will have severely degraded performance if you use
anything besides the bulb it was designed around. If you've had physics
you might be familiar with the study of optics, namely focal points.
Move a source out of the focal point of the system (reflector and/or
lens optics) and the beam goes completely out of focus. What do you
think gives better performance - in focus or out of focus? These LED
replacements can't place all its LEDs in the focal point of the system -
namely where the filament of the incandescent bulb is. Now, if a lamp
were designed around LEDs originally, then instead of a single focal
point it will have been designed with multiple focal points (one for
each LED) to spread the light from the LEDs into the beam pattern
required for the lamp's function.
That brings me to the next point - incandescent bulbs have
omnidirectional light output (fancy way of saying it puts out light in
all directions in mostly equal intensities) and the lamps that use them
were designed with this in mind. LEDs are directional with peak outputs
typically along axis dropping to 50% intensity in narrow, medium, and
wide beam spreads usually no greater than 60°. Combine this with the
fact that the LEDs are out of focus in the lens/reflector system and you
get far less light coming out the lamp than had you simply used the
original incandescent bulb. The only way to have an LED replacement of
an incandescent bulb is to somehow convert an LED's directional output
into an omnidirectional output *identical* to that of the intended
incandescent bulb. I haven't seen anything in development that would
accomplish this and frankly think that it would be cost-prohibitive.
Definitely the botch jobs that are produced right now don't even come close.
And then you have the problem of heat buildup. In order to get the
proper amount of light, you need several LEDs. All those LEDs generate
heat and when placed in a form like a miniature incandescent bulb, the
heat gets trapped. As LEDs heat up, their light output decreases. I've
seen outputs drop to 10% their starting intensity within a few minutes
(hence, my earlier statement). The performance is even worse with high
performance LEDs like the Luxeon which need a decent heat sink in order
to achieve optimal performance and there just isn't enough room in the
"bulb" for one.
Agreed, but not directly to the point of my follow up question. Though...
it does raise a good question... What is the difference between OEM LED
systems and aftermarket systems? One would think that since the OEM
systems meet DOT specs that it would not be so improbable for aftermarket
stuff to do so equally. I'm wondering if some of the more current stuff
might indeed meet DOT specs.
OEM LED systems are designed to use LEDs. Aftermarket LED systems
designed to replace OEM LED systems (in other words, the entire
automotive lamp), may perform just as well as the OEM - it depends on
the aftermarket manufacturer. There are good aftermarket manufacturers
and there are crap aftermarket manufacturers. The lamps also may not
perform as well as the OEM but still meet minimal DOT specs (many
quality OEs produce lamps that exceed federal requirements several times
over).
Aftermarket LED systems designed to replace incandescent automotive
lamps (again in other words, the entire lamp) may perform just as well
as the OEM incandescent depending on the aftermarket manufacturer with
the same caveats as previous. For a while DOT did not allow this, but
they reversed their decision and now its legal.
OEM LED systems designed to replace incandescent bulbs do not exist.
Way too much liability as well as the reasons I stated above. It's
possible, but expect them to cost if it ever does happen.
Aftermarket LED systems designed to replace OEM incandescent bulbs is
what we were discussing above. I haven't seen one that is worth anything.
OEM LED systems that are replaceable are in the works, but not yet
through development as far as I know. These would go into lamps
designed around the LEDs and would not be interchangeable with
incandescents. You can do a patent search for patent # 6846101 to learn
more.