"Paul Hovnanian P.E." <paul@hovnanian.com> wrote in message
news:450057BE.5B9C800D@hovnanian.com...

>
> I think what Doug is saying is that LED lamps should only be used in
> fixtures (taillight assemblies) designed to used them. Likewise,
> incandescent bulbs should only be used in fixtures designed for them.

Correct - but I was asking specifically about his research experiences.

>
> There is nothing wrong with LED taillights. Many high priced vehicles
> have them and they work quite well. But only because the entire lighting
> system has been designed around them.
>

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.

--

-Mike-
mmarlowREMOVE@alltel.net

 

Mike Marlow wrote:
> "Douglas G. Cummins" <Douglas.Cummins@MAPSONcalcoast-itl.com> wrote in
> message news:9EHLg.4211$v%4.1416@newsread1.news.pas.earthl ink.net...
>
>>And just so that you know, I am an expert in automotive lighting systems
>>including turn signals and the flashers they use. I've tested them for
>>more than 10 years now and I have not seen one LED replacement bulb for
>>an incandescent that performs even close to one-tenth the performance of
>>the original bulb. Designers do have plans for replaceable LED modules,
>>but they will not be interchangeable with incandescents so that they
>>should be used only with the lamps they were designed to be used with.
>
>
> 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 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 s 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.

>>There is nothing wrong with LED taillights. Many high priced vehicles
>>> have them and they work quite well. But only because the entire lighting
>>> system has been designed around them.
>
>
> 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.

--
Douglas Cummins
Calcoast - ITL

 

Mike Marlow wrote:
> "Douglas G. Cummins" <Douglas.Cummins@MAPSONcalcoast-itl.com> wrote in
> message news:9EHLg.4211$v%4.1416@newsread1.news.pas.earthl ink.net...
>
>>And just so that you know, I am an expert in automotive lighting systems
>>including turn signals and the flashers they use. I've tested them for
>>more than 10 years now and I have not seen one LED replacement bulb for
>>an incandescent that performs even close to one-tenth the performance of
>>the original bulb. Designers do have plans for replaceable LED modules,
>>but they will not be interchangeable with incandescents so that they
>>should be used only with the lamps they were designed to be used with.
>
>
> 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 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 s 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.

>>There is nothing wrong with LED taillights. Many high priced vehicles
>>> have them and they work quite well. But only because the entire lighting
>>> system has been designed around them.
>
>
> 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.

--
Douglas Cummins
Calcoast - ITL

 

"Douglas G. Cummins" <Douglas.Cummins@MAPSONcalcoast-itl.com> wrote in
message news:zO0Mg.4684$v%4.186@newsread1.news.pas.earthli nk.net...

>
> Well, first and foremost the fact that a lamp designed around an...

<snip>

....You can do a patent search for patent # 6846101 to learn more.

Excellent stuff Doug. Thanks for taking the time for such a write up.

--

-Mike-
mmarlowREMOVE@alltel.net

 

"Douglas G. Cummins" <Douglas.Cummins@MAPSONcalcoast-itl.com> wrote in
message news:zO0Mg.4684$v%4.186@newsread1.news.pas.earthli nk.net...

>
> Well, first and foremost the fact that a lamp designed around an...

<snip>

....You can do a patent search for patent # 6846101 to learn more.

Excellent stuff Doug. Thanks for taking the time for such a write up.

--

-Mike-
mmarlowREMOVE@alltel.net

 

"Mike Marlow" <mmarlow@alltel.net> wrote in message
news:f2f28$45006df6$471fbb8f$12599@ALLTEL.NET...
>
> "Paul Hovnanian P.E." <paul@hovnanian.com> wrote in message
> news:450057BE.5B9C800D@hovnanian.com...
>
>>
>> I think what Doug is saying is that LED lamps should only be used in
>> fixtures (taillight assemblies) designed to used them. Likewise,
>> incandescent bulbs should only be used in fixtures designed for them.
>
> Correct - but I was asking specifically about his research experiences.
>
>>
>> There is nothing wrong with LED taillights. Many high priced vehicles
>> have them and they work quite well. But only because the entire lighting
>> system has been designed around them.
>>
>
> 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.
>
If someone came up with an aftermarket tail light assembly that used LED's -
for example the aftermarket LED trailer light assemblies that are used for
boat trailers are DOT approved - I'm sure it would work well. The problem
with retrofits is that LEDs don't have the same pattern of light as the
original lamps. Consequently, the light output of the assembly has to be
wrong because the light source is not where it is designed to be. An 1157
makes unidirectional light. It radiates 407 lumens in all directions from an
area of approximately .1 inch x .25 inches. I know of no LED that does that.

 

"Mike Marlow" <mmarlow@alltel.net> wrote in message
news:f2f28$45006df6$471fbb8f$12599@ALLTEL.NET...
>
> "Paul Hovnanian P.E." <paul@hovnanian.com> wrote in message
> news:450057BE.5B9C800D@hovnanian.com...
>
>>
>> I think what Doug is saying is that LED lamps should only be used in
>> fixtures (taillight assemblies) designed to used them. Likewise,
>> incandescent bulbs should only be used in fixtures designed for them.
>
> Correct - but I was asking specifically about his research experiences.
>
>>
>> There is nothing wrong with LED taillights. Many high priced vehicles
>> have them and they work quite well. But only because the entire lighting
>> system has been designed around them.
>>
>
> 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.
>
If someone came up with an aftermarket tail light assembly that used LED's -
for example the aftermarket LED trailer light assemblies that are used for
boat trailers are DOT approved - I'm sure it would work well. The problem
with retrofits is that LEDs don't have the same pattern of light as the
original lamps. Consequently, the light output of the assembly has to be
wrong because the light source is not where it is designed to be. An 1157
makes unidirectional light. It radiates 407 lumens in all directions from an
area of approximately .1 inch x .25 inches. I know of no LED that does that.

 

> 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.
>

Actually it's inconceivable that this could ever be done. The
filaments used in the signal bulbs are helical coils which emit into a
volume (not surface emitters) and this does matter in the optical
design. You can't just replace them with a round cylinder of
semiconductor material and get the same results So instead you would
need to find a way to coil the semiconductor material and then somehow
imitate the varying temperature of the inside and outside of the coil,
and the change in output from the center to the ends of the coil to get
the same output distribution. Not gonna happen.

 

> 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.
>

Actually it's inconceivable that this could ever be done. The
filaments used in the signal bulbs are helical coils which emit into a
volume (not surface emitters) and this does matter in the optical
design. You can't just replace them with a round cylinder of
semiconductor material and get the same results So instead you would
need to find a way to coil the semiconductor material and then somehow
imitate the varying temperature of the inside and outside of the coil,
and the change in output from the center to the ends of the coil to get
the same output distribution. Not gonna happen.

 

Boxman wrote:

>>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.
>>
>
> Actually it's inconceivable that this could ever be done. The
> filaments used in the signal bulbs are helical coils which emit into a
> volume (not surface emitters) and this does matter in the optical
> design. You can't just replace them with a round cylinder of
> semiconductor material and get the same results So instead you would
> need to find a way to coil the semiconductor material and then somehow
> imitate the varying temperature of the inside and outside of the coil,
> and the change in output from the center to the ends of the coil to get
> the same output distribution. Not gonna happen.

The reason I hedged my statement is that it is conceivable that an LED
based substitute for the coil may be created. For instance, a
fiberoptic light pipe to a cylindrical lens the dimensions of the
filament (more than likely placing the LED source outside the lamp
making it really a light pipe bulb replacement). Theoretically possible
but just not practicable nor really justifiable at this point in time.
I don't see it happening though.


--
Douglas Cummins
Calcoast - ITL

 

Boxman wrote:

>>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.
>>
>
> Actually it's inconceivable that this could ever be done. The
> filaments used in the signal bulbs are helical coils which emit into a
> volume (not surface emitters) and this does matter in the optical
> design. You can't just replace them with a round cylinder of
> semiconductor material and get the same results So instead you would
> need to find a way to coil the semiconductor material and then somehow
> imitate the varying temperature of the inside and outside of the coil,
> and the change in output from the center to the ends of the coil to get
> the same output distribution. Not gonna happen.

The reason I hedged my statement is that it is conceivable that an LED
based substitute for the coil may be created. For instance, a
fiberoptic light pipe to a cylindrical lens the dimensions of the
filament (more than likely placing the LED source outside the lamp
making it really a light pipe bulb replacement). Theoretically possible
but just not practicable nor really justifiable at this point in time.
I don't see it happening though.


--
Douglas Cummins
Calcoast - ITL

 

Bob wrote:
>
[snip]

> If someone came up with an aftermarket tail light assembly that used LED's -
> for example the aftermarket LED trailer light assemblies that are used for
> boat trailers are DOT approved - I'm sure it would work well. The problem
> with retrofits is that LEDs don't have the same pattern of light as the
> original lamps. Consequently, the light output of the assembly has to be
> wrong because the light source is not where it is designed to be. An 1157
> makes unidirectional light. It radiates 407 lumens in all directions from an
> area of approximately .1 inch x .25 inches. I know of no LED that does that.

I've seen aftermarket taillight assemblies* that use LEDs. Installing
them involves replacing the entire taillight assembly, not just sticking
in an LED assembly in the existing lamp socket.

* I don't know if they are approved units, but they appear to be
configured similarly to LED-based taillights provided on other models as
original equipment.

--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Dyslexics have more fnu.

 

Bob wrote:
>
[snip]

> If someone came up with an aftermarket tail light assembly that used LED's -
> for example the aftermarket LED trailer light assemblies that are used for
> boat trailers are DOT approved - I'm sure it would work well. The problem
> with retrofits is that LEDs don't have the same pattern of light as the
> original lamps. Consequently, the light output of the assembly has to be
> wrong because the light source is not where it is designed to be. An 1157
> makes unidirectional light. It radiates 407 lumens in all directions from an
> area of approximately .1 inch x .25 inches. I know of no LED that does that.

I've seen aftermarket taillight assemblies* that use LEDs. Installing
them involves replacing the entire taillight assembly, not just sticking
in an LED assembly in the existing lamp socket.

* I don't know if they are approved units, but they appear to be
configured similarly to LED-based taillights provided on other models as
original equipment.

--
Paul Hovnanian mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Dyslexics have more fnu.

 

Holy cow. I never thought my question would spark such a discussion!

Here's the LED bulbs I bought: http://tinyurl.com/nzxrn

I want to note, nowhere do they mention this bulb as being DOT approved
or not, or for off-road/show use only. I think that's a big mistake on
their part.

Initially I meant them for the turn signals on my motorcycle. But it was
immediately obvious they did not function as well as the incandescent
1073 bulbs, so I decided to try them in the rear turn signals of my 2006
Sonata.

With one LED installed on one side, and the stock incandescent in the
other.. I ran the hazard flasher and stood behind the car to compare
them. I then moved the car into the street and walked a ways away.. I'd
say 3 city blocks, though there's no 'blocks' here. I found the LED to
be much more 'obvious', and didn't have that lazy attack/decay that the
incandescnet has. The LED was also a brighter color of amber. Do they
work as well in snow, fog, rain, direct sunlight? I didn't go that far to
test. I put the old bulb back in, and started researching the flasher,
which led to my original post.

And I'm all about safety, I ride a motorcycle. What everyone's said
about the DOT specs and safety is completely right. It wasn't my
intention to defeat the safety of the rear turn signals. I only bought
these things and now had no use for them, and given my little test, they
looked reasonably acceptable in my Sonata.

And not to be funny, but the bit about the flasher being responsible for
alerting you to a burned out bulb; I do a walk-around on my vehicles
routinely. I have a 2001 Sante Fe and the side marker lights chronically
burn out, yet nothing brings that to my attention. And I drive a lot for
work, and see cars with one, two or all brake lights out, or cars with
those stupid clear aftermarket light housings that look like someone is
shining a flashlight through them from the trunk when they step on the
brakes. Not long ago, Florida stopped inspecting vehicles, which I think
was a terrible idea. But anyway, my point is.. if you're going to meddle
with the safety aspect of something on a vehicle, you have to be
responsible for it, and if the flasher no longer warns of a bulb being
out, I'd see it when I do my walk-around. (I picked that habit up from
flying.)

Anyway, thanks for all the information. It's better to be safe than
sorry.

Kiran

 

Holy cow. I never thought my question would spark such a discussion!

Here's the LED bulbs I bought: http://tinyurl.com/nzxrn

I want to note, nowhere do they mention this bulb as being DOT approved
or not, or for off-road/show use only. I think that's a big mistake on
their part.

Initially I meant them for the turn signals on my motorcycle. But it was
immediately obvious they did not function as well as the incandescent
1073 bulbs, so I decided to try them in the rear turn signals of my 2006
Sonata.

With one LED installed on one side, and the stock incandescent in the
other.. I ran the hazard flasher and stood behind the car to compare
them. I then moved the car into the street and walked a ways away.. I'd
say 3 city blocks, though there's no 'blocks' here. I found the LED to
be much more 'obvious', and didn't have that lazy attack/decay that the
incandescnet has. The LED was also a brighter color of amber. Do they
work as well in snow, fog, rain, direct sunlight? I didn't go that far to
test. I put the old bulb back in, and started researching the flasher,
which led to my original post.

And I'm all about safety, I ride a motorcycle. What everyone's said
about the DOT specs and safety is completely right. It wasn't my
intention to defeat the safety of the rear turn signals. I only bought
these things and now had no use for them, and given my little test, they
looked reasonably acceptable in my Sonata.

And not to be funny, but the bit about the flasher being responsible for
alerting you to a burned out bulb; I do a walk-around on my vehicles
routinely. I have a 2001 Sante Fe and the side marker lights chronically
burn out, yet nothing brings that to my attention. And I drive a lot for
work, and see cars with one, two or all brake lights out, or cars with
those stupid clear aftermarket light housings that look like someone is
shining a flashlight through them from the trunk when they step on the
brakes. Not long ago, Florida stopped inspecting vehicles, which I think
was a terrible idea. But anyway, my point is.. if you're going to meddle
with the safety aspect of something on a vehicle, you have to be
responsible for it, and if the flasher no longer warns of a bulb being
out, I'd see it when I do my walk-around. (I picked that habit up from
flying.)

Anyway, thanks for all the information. It's better to be safe than
sorry.

Kiran