# Halogen envelope design



## Kabana (Aug 2, 2021)

I have been keeping an eye on the envelope shape of the H4/HB2/9003 from about 2008 when Philips started hitting the market hard with all their so called +30, then +50, then +80 and now _+200 _bulbs.

It was about then I noticed the Philips and Osram H4/9003 had a slim envelope with a fatter base. These brands H4/9003 envelope looked almost the same design as their H7.

I thought this might be required to get the so called +30, +50 etc figures they advertise. But obviously it isn't (I know they get the +# etc from a thinner coil) as GE/Tungsram are using the old style fat envelope with the flatter top to also get their +50, +130 etc figures.

In case you need images.
Philips RV +150 H4, Osram NB +150 H4, vs Tungsram ML +150 H4














So it is Philips/Osram using the narrower H7 envelope to save $$$?

How long ago did Philips/Osram switch to the narrower H4 envelope?


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## Alaric Darconville (Aug 2, 2021)

The narrower envelope means faster heating of the envelope, making the halogen cycle (where bits of filament that fly off are redeposited on the filament instead of sticking to the envelope) starts occur faster and work more effectively.


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## Kabana (Aug 2, 2021)

Alaric Darconville said:


> The narrower envelope means faster heating of the envelope, making the halogen cycle (where bits of filament that fly off are redeposited on the filament instead of sticking to the envelope) starts occur faster and work more effectively.


OK I concur. 
But narrower envelope= less volume= greater heat retention =less filamnt life?


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## Alaric Darconville (Aug 2, 2021)

It's still a more effective halogen cycle. 

Long filament life can be a bad thing. It's a sign the filament is potentially underheated. With halogen bulbs, if the temperature is too low, the bits of filament that fly off will just stick to the envelope.
"Long Life" bulbs are particularly bad because their lumen maintenance is poor. Long before the bulb has stopped lighting, they've stopped providing quality light (the filament degrades and the envelope darkens). With real high-performance bulbs, they will burn out before the lumen maintenance (and lamp focus) is degraded. 

Yes, you'll be replacing bulbs more frequently, but you'll be seeing better. Just carry a spare (although some cars do make it difficult to change bulbs, so changing in the field may be a bit of a pain).


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## Autolamps (Aug 3, 2021)

They changed from hard glass to quartz glass in recent years to increase fill pressure (atm) inside the lamp. Hard glass had its limits to pressure.


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## Alaric Darconville (Aug 3, 2021)

Autolamps said:


> They changed from hard glass to quartz glass in recent years to increase fill pressure (atm) inside the lamp. Hard glass had its limits to pressure.


However, it doesn't render anything already said about the halogen cycle and "long life bulbs" untrue. It does mean you have to be careful to install them with the envelope extremely clean, because if the bulb shatters it will do so in a spectacular, and lamp-ruining, way. Also, poorly sealed (and almost counterintuitively, *vented*) lamp assemblies can allow water ingress without associated release of excess moisture, and water hitting a lit bulb is not a good thing.

For those that don't know what "atm" means, it is one "atmosphere", the standard unit of atmospheric pressure at sea level. It's defined as 101,325 Pa (Pascals), or 760 mm Hg (millimeters of mercury), or 14.696 psi. A halogen bulb can be pressurized to around 7 or 8 atm (sometimes much much more) and the pressure increases when the lamp is operating due to the much higher temperatures.


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## -Virgil- (Aug 3, 2021)

Kabana said:


> narrower envelope= less volume



Yes.



> = greater heat retention =less filamnt life?



No. The capsule volume itself doesn't have a big impact on the filament temperature. It has a much bigger effect on the capsule wall temperature, which, as Alaric mentions, is crucial to the onset and maintenance of the halogen cycle.

And as Autolamps mentions, smaller envelopes can facilitate higher fill pressures, which are beneficial for both output and life. Philips' capsules have primarily been quartz for many years; Osram and Tungsram have had a more diverse product mix of hard glass and quartz. Each material has its benefits and drawbacks for vehicle headlight lamps; one is not uniformly better than the other, and there are many design and construction parameters that factor in, so you can't dependably predict that bulb "A" with a smaller quartz capsule is necessarily better than bulb "B" with a larger hard glass one. The Tungsram Megalight bulbs are hard glass/larger, but they consistently hold their own in performance and life amidst competition with the Philips and Osram products. By the way, no, the Tungsram Megalight +150 bulb does not have a "100% xenon fill". Neither does any other halogen bulb. If it did, it wouldn't be a halogen bulb. In fact, above a certain percentage of Xe, you start getting operational problems like coil-to-coil arcing. Somebody let the marketing staff out of their cage again! Also, last tests I ran showed Tungsram's Megalight +120 beating the performance _and_ life of the Megalight Ultra +150. Not hard to figure out...the +150 has more and darker blue tinting over a greater area of the capsule, and when light has to pass through a blue filter, less of it reaches the road.

At least this "100% xenon" claim is not as ridiculously dumb as marketing-driven also-ran companies like IPF promoting their pointlessly extra-_large_ "fatboy" capsules as somehow brawnier, tougher, and better...which they are not.


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## turbodog (Aug 3, 2021)

Alaric Darconville said:


> ... allow water ingress without associated release of excess moisture, and water hitting a lit bulb is not a good thing.
> 
> ...



Yup. Lost BOTH headlights at the same time due to water ingress. That was a totally fun experience!

And no, I didn't drive into a pond.

Was on low beam... lost both lights within a couple of seconds of one another. Intuitively switched to high beams. Light restored! Yay! Then they burned out in a second or two as well. Drove home with a 4d maglite out the window.


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## Alaric Darconville (Aug 3, 2021)

turbodog said:


> Yup. Lost BOTH headlights at the same time due to water ingress. That was a totally fun experience!


That drive home had to be harrowing. 

Careful inspection of your headlamps from time to time can help prevent that, in that when you see a pool of water in the lamps or excessive condensation inside the lens, it's time to replace them.


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## John_Galt (Aug 3, 2021)

-Virgil- is envelope temperature something that is balance against the type/coverage area of blue tinting? Clearly the filtration effect will result in higher envelope temps, is this so specific to the area directly coated that manufacturers attempt to alter the envelope thickness under/immediately in contact with any coating, or is it such a small difference in lifespan that it would be a waste of time and money to thoroughly examine?


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## -Virgil- (Aug 3, 2021)

John_Galt said:


> is envelope temperature something that is balance against the type/coverage area of blue tinting?



Any minor difference it might make is not significant enough to drive modifications to the envelope itself. Consider, the envelope is already robust enough vs. thermal gradients to handle the blacktop...!


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## John_Galt (Aug 3, 2021)

That's fair, I would ***-ume that the top of the bulb sees less heat radiated directly to it from the filament(s), although it has to reach some even temp, lest it be the point of failure.

Somewhat on topic, the last set of osram selective yellow 9003's I purchased from Stern ended up failing when the tinted quartz envelope melted and sagged enough to touch the low beam filament. Was an interesting way to fail, I dont seem to have taken pictures of it, however.


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## turbodog (Aug 3, 2021)

Alaric Darconville said:


> That drive home had to be harrowing.
> 
> Careful inspection of your headlamps from time to time can help prevent that, in that when you see a pool of water in the lamps or excessive condensation inside the lens, it's time to replace them.



Turned out the reflector/lens assembly was not airtight. I hit some water just right, which splashed onto the back of the lights, cooled them somewhat, and got sucked into the assembly due to air contracting. When sucked in, it went straight onto the bulb... and downhill from there.

Remove bulb, vacuum broken fragments, replace, and apply TONS of rtv. Short version: ford's 97 ranger headlights really sucked.


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## Kabana (Aug 4, 2021)

Alaric Darconville said:


> It's still a more effective halogen cycle.
> 
> Long filament life can be a bad thing. It's a sign the filament is potentially underheated. With halogen bulbs, if the temperature is too low, the bits of filament that fly off will just stick to the envelope.
> "Long Life" bulbs are particularly bad because their lumen maintenance is poor. Long before the bulb has stopped lighting, they've stopped providing quality light (the filament degrades and the envelope darkens). With real high-performance bulbs, they will burn out before the lumen maintenance (and lamp focus) is degraded.
> ...



I'm aware of the LL bulbs physics, their performance and why auto makers use them.

Which brings me to the next question which is the difference in offerings in the different brands +150 H4 lifespan:

Philps XV +150 claim 540 hours

Philips Racing Vision +150 - 200 hours

Osram NB +150 - 200 hours (Tc low beam)

Tungsram ML +150 - 250 hours

We all know the end user would likely only get 1/2 to 2/3 of these lab test claimed hours.

Interesting the Philips RacingVision 150 has been replaced by the RacingVision +200 with claimed 400 hours.

So what is Philips doing to get 400+hours vs Osram/Tungsram's 200- 250? Better tech or is Philips diddling its lab test numbers where the others lab tests are more reasonably attainable by the end user?


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## Alaric Darconville (Aug 4, 2021)

turbodog said:


> Turned out the reflector/lens assembly was not airtight.


It's not supposed to be airtight.



> Remove bulb, vacuum broken fragments, replace, and apply TONS of rtv. Short version: ford's 97 ranger headlights really sucked.


Windshield urethane. RTV silicone will ruin the (already quite ruined) headlamps. Time to just order new lamps, not try to repair those.


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## Alaric Darconville (Aug 4, 2021)

Kabana said:


> I'm aware of the LL bulbs physics; their performance


It wasn't quite clear that you did from your initial (and further) questions in the thread.

Changes in fill gas composition, pressure, coil winding technique, specific metallurgy, can all contribute to changes in bulb life at the test voltage. 

And, similar to things like hard drives, there are tests run on large batches of bulbs to get the average rated life. Those tests are under controlled conditions without the abuse a bulb would ordinarily go through (vibration, repeated cycling, voltage spikes, etc). Surely you've experienced only one bulb burning out in a certain amount of time, or seen other vehicles with just one failed bulb, which demonstrates that bulb life is a wide band, not a fixed point.


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## turbodog (Aug 4, 2021)

Alaric Darconville said:


> It's not supposed to be airtight.
> 
> 
> Windshield urethane. RTV silicone will ruin the (already quite ruined) headlamps. Time to just order new lamps, not try to repair those.



Really? Surprising. Where's the vent? All my current vehicles seem to have a nice sealed bulb assembly (rubber boot covering it all).

Ford must have picked a crappy place for the vent then.


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## Alaric Darconville (Aug 4, 2021)

turbodog said:


> Really? Surprising. Where's the vent? All my current vehicles seem to have a nice sealed bulb assembly (rubber boot covering it all).


Very few are completely sealed, most will have venting areas that are not completely obvious. And the rubber boot 'sealing' the bulb to the lamp assembly will allow bidirectional air flow. If they were completely airtight, pressure changes from lamp heating/cooling could be a problem.

I don't have a picture immediately available, but on the '95 Previa's, each headlamp has tubelike projections on the rear of it, with a dense but permeable foam inside that tube, and a rubber cover with a duct on it to hold it that foam in and permitting bidirectional air flow. The foam keeps the spiders from exploring the lamp (and can stop small amounts of water from getting in so long as the lamp isn't submerged).


----------



## Autolamps (Aug 4, 2021)

John_Galt said:


> -Virgil- is envelope temperature something that is balance against the type/coverage area of blue tinting? Clearly the filtration effect will result in higher envelope temps, is this so specific to the area directly coated that manufacturers attempt to alter the envelope thickness under/immediately in contact with any coating, or is it such a small difference in lifespan that it would be a waste of time and money to thoroughly examine?


All glass envelopes are the same regardless if selective coated or not. Way too much detail to have different thicknesses for coated/uncoated products. Mass economy of scale for glass melts and tube tube manufacturing.


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## -Virgil- (Aug 4, 2021)

Kabana said:


> the next question which is the difference in offerings in the different brands +150 H4 lifespan (...) So what is Philips doing to get 400+hours vs Osram/Tungsram's 200- 250?



Most likely? Testing differently.



> We all know the end user would likely only get 1/2 to 2/3 of these lab test claimed hours.



That's not necessarily true. Actual bulb life can range from much shorter to much longer than published life figures. It depends on what voltage the car delivers to the bulbs, and other factors, too: is the voltage stable, or is it "dirty" (spiking up to high voltage momentarily, etc)? Are the headlamps on a soft-start and/or PWM circuit? Are the headlamps lit while the engine is being started and/or stopped?


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## Kabana (Aug 2, 2021)

I have been keeping an eye on the envelope shape of the H4/HB2/9003 from about 2008 when Philips started hitting the market hard with all their so called +30, then +50, then +80 and now _+200 _bulbs.

It was about then I noticed the Philips and Osram H4/9003 had a slim envelope with a fatter base. These brands H4/9003 envelope looked almost the same design as their H7.

I thought this might be required to get the so called +30, +50 etc figures they advertise. But obviously it isn't (I know they get the +# etc from a thinner coil) as GE/Tungsram are using the old style fat envelope with the flatter top to also get their +50, +130 etc figures.

In case you need images.
Philips RV +150 H4, Osram NB +150 H4, vs Tungsram ML +150 H4














So it is Philips/Osram using the narrower H7 envelope to save $$$?

How long ago did Philips/Osram switch to the narrower H4 envelope?


----------



## Alaric Darconville (Aug 2, 2021)

The narrower envelope means faster heating of the envelope, making the halogen cycle (where bits of filament that fly off are redeposited on the filament instead of sticking to the envelope) starts occur faster and work more effectively.


----------



## Kabana (Aug 2, 2021)

Alaric Darconville said:


> The narrower envelope means faster heating of the envelope, making the halogen cycle (where bits of filament that fly off are redeposited on the filament instead of sticking to the envelope) starts occur faster and work more effectively.


OK I concur. 
But narrower envelope= less volume= greater heat retention =less filamnt life?


----------



## Alaric Darconville (Aug 2, 2021)

It's still a more effective halogen cycle. 

Long filament life can be a bad thing. It's a sign the filament is potentially underheated. With halogen bulbs, if the temperature is too low, the bits of filament that fly off will just stick to the envelope.
"Long Life" bulbs are particularly bad because their lumen maintenance is poor. Long before the bulb has stopped lighting, they've stopped providing quality light (the filament degrades and the envelope darkens). With real high-performance bulbs, they will burn out before the lumen maintenance (and lamp focus) is degraded. 

Yes, you'll be replacing bulbs more frequently, but you'll be seeing better. Just carry a spare (although some cars do make it difficult to change bulbs, so changing in the field may be a bit of a pain).


----------



## Autolamps (Aug 3, 2021)

They changed from hard glass to quartz glass in recent years to increase fill pressure (atm) inside the lamp. Hard glass had its limits to pressure.


----------



## Alaric Darconville (Aug 3, 2021)

Autolamps said:


> They changed from hard glass to quartz glass in recent years to increase fill pressure (atm) inside the lamp. Hard glass had its limits to pressure.


However, it doesn't render anything already said about the halogen cycle and "long life bulbs" untrue. It does mean you have to be careful to install them with the envelope extremely clean, because if the bulb shatters it will do so in a spectacular, and lamp-ruining, way. Also, poorly sealed (and almost counterintuitively, *vented*) lamp assemblies can allow water ingress without associated release of excess moisture, and water hitting a lit bulb is not a good thing.

For those that don't know what "atm" means, it is one "atmosphere", the standard unit of atmospheric pressure at sea level. It's defined as 101,325 Pa (Pascals), or 760 mm Hg (millimeters of mercury), or 14.696 psi. A halogen bulb can be pressurized to around 7 or 8 atm (sometimes much much more) and the pressure increases when the lamp is operating due to the much higher temperatures.


----------



## -Virgil- (Aug 3, 2021)

Kabana said:


> narrower envelope= less volume



Yes.



> = greater heat retention =less filamnt life?



No. The capsule volume itself doesn't have a big impact on the filament temperature. It has a much bigger effect on the capsule wall temperature, which, as Alaric mentions, is crucial to the onset and maintenance of the halogen cycle.

And as Autolamps mentions, smaller envelopes can facilitate higher fill pressures, which are beneficial for both output and life. Philips' capsules have primarily been quartz for many years; Osram and Tungsram have had a more diverse product mix of hard glass and quartz. Each material has its benefits and drawbacks for vehicle headlight lamps; one is not uniformly better than the other, and there are many design and construction parameters that factor in, so you can't dependably predict that bulb "A" with a smaller quartz capsule is necessarily better than bulb "B" with a larger hard glass one. The Tungsram Megalight bulbs are hard glass/larger, but they consistently hold their own in performance and life amidst competition with the Philips and Osram products. By the way, no, the Tungsram Megalight +150 bulb does not have a "100% xenon fill". Neither does any other halogen bulb. If it did, it wouldn't be a halogen bulb. In fact, above a certain percentage of Xe, you start getting operational problems like coil-to-coil arcing. Somebody let the marketing staff out of their cage again! Also, last tests I ran showed Tungsram's Megalight +120 beating the performance _and_ life of the Megalight Ultra +150. Not hard to figure out...the +150 has more and darker blue tinting over a greater area of the capsule, and when light has to pass through a blue filter, less of it reaches the road.

At least this "100% xenon" claim is not as ridiculously dumb as marketing-driven also-ran companies like IPF promoting their pointlessly extra-_large_ "fatboy" capsules as somehow brawnier, tougher, and better...which they are not.


----------



## turbodog (Aug 3, 2021)

Alaric Darconville said:


> ... allow water ingress without associated release of excess moisture, and water hitting a lit bulb is not a good thing.
> 
> ...



Yup. Lost BOTH headlights at the same time due to water ingress. That was a totally fun experience!

And no, I didn't drive into a pond.

Was on low beam... lost both lights within a couple of seconds of one another. Intuitively switched to high beams. Light restored! Yay! Then they burned out in a second or two as well. Drove home with a 4d maglite out the window.


----------



## Alaric Darconville (Aug 3, 2021)

turbodog said:


> Yup. Lost BOTH headlights at the same time due to water ingress. That was a totally fun experience!


That drive home had to be harrowing. 

Careful inspection of your headlamps from time to time can help prevent that, in that when you see a pool of water in the lamps or excessive condensation inside the lens, it's time to replace them.


----------



## John_Galt (Aug 3, 2021)

-Virgil- is envelope temperature something that is balance against the type/coverage area of blue tinting? Clearly the filtration effect will result in higher envelope temps, is this so specific to the area directly coated that manufacturers attempt to alter the envelope thickness under/immediately in contact with any coating, or is it such a small difference in lifespan that it would be a waste of time and money to thoroughly examine?


----------



## -Virgil- (Aug 3, 2021)

John_Galt said:


> is envelope temperature something that is balance against the type/coverage area of blue tinting?



Any minor difference it might make is not significant enough to drive modifications to the envelope itself. Consider, the envelope is already robust enough vs. thermal gradients to handle the blacktop...!


----------



## John_Galt (Aug 3, 2021)

That's fair, I would ***-ume that the top of the bulb sees less heat radiated directly to it from the filament(s), although it has to reach some even temp, lest it be the point of failure.

Somewhat on topic, the last set of osram selective yellow 9003's I purchased from Stern ended up failing when the tinted quartz envelope melted and sagged enough to touch the low beam filament. Was an interesting way to fail, I dont seem to have taken pictures of it, however.


----------



## turbodog (Aug 3, 2021)

Alaric Darconville said:


> That drive home had to be harrowing.
> 
> Careful inspection of your headlamps from time to time can help prevent that, in that when you see a pool of water in the lamps or excessive condensation inside the lens, it's time to replace them.



Turned out the reflector/lens assembly was not airtight. I hit some water just right, which splashed onto the back of the lights, cooled them somewhat, and got sucked into the assembly due to air contracting. When sucked in, it went straight onto the bulb... and downhill from there.

Remove bulb, vacuum broken fragments, replace, and apply TONS of rtv. Short version: ford's 97 ranger headlights really sucked.


----------



## Kabana (Aug 4, 2021)

Alaric Darconville said:


> It's still a more effective halogen cycle.
> 
> Long filament life can be a bad thing. It's a sign the filament is potentially underheated. With halogen bulbs, if the temperature is too low, the bits of filament that fly off will just stick to the envelope.
> "Long Life" bulbs are particularly bad because their lumen maintenance is poor. Long before the bulb has stopped lighting, they've stopped providing quality light (the filament degrades and the envelope darkens). With real high-performance bulbs, they will burn out before the lumen maintenance (and lamp focus) is degraded.
> ...



I'm aware of the LL bulbs physics, their performance and why auto makers use them.

Which brings me to the next question which is the difference in offerings in the different brands +150 H4 lifespan:

Philps XV +150 claim 540 hours

Philips Racing Vision +150 - 200 hours

Osram NB +150 - 200 hours (Tc low beam)

Tungsram ML +150 - 250 hours

We all know the end user would likely only get 1/2 to 2/3 of these lab test claimed hours.

Interesting the Philips RacingVision 150 has been replaced by the RacingVision +200 with claimed 400 hours.

So what is Philips doing to get 400+hours vs Osram/Tungsram's 200- 250? Better tech or is Philips diddling its lab test numbers where the others lab tests are more reasonably attainable by the end user?


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## Alaric Darconville (Aug 4, 2021)

turbodog said:


> Turned out the reflector/lens assembly was not airtight.


It's not supposed to be airtight.



> Remove bulb, vacuum broken fragments, replace, and apply TONS of rtv. Short version: ford's 97 ranger headlights really sucked.


Windshield urethane. RTV silicone will ruin the (already quite ruined) headlamps. Time to just order new lamps, not try to repair those.


----------



## Alaric Darconville (Aug 4, 2021)

Kabana said:


> I'm aware of the LL bulbs physics; their performance


It wasn't quite clear that you did from your initial (and further) questions in the thread.

Changes in fill gas composition, pressure, coil winding technique, specific metallurgy, can all contribute to changes in bulb life at the test voltage. 

And, similar to things like hard drives, there are tests run on large batches of bulbs to get the average rated life. Those tests are under controlled conditions without the abuse a bulb would ordinarily go through (vibration, repeated cycling, voltage spikes, etc). Surely you've experienced only one bulb burning out in a certain amount of time, or seen other vehicles with just one failed bulb, which demonstrates that bulb life is a wide band, not a fixed point.


----------



## turbodog (Aug 4, 2021)

Alaric Darconville said:


> It's not supposed to be airtight.
> 
> 
> Windshield urethane. RTV silicone will ruin the (already quite ruined) headlamps. Time to just order new lamps, not try to repair those.



Really? Surprising. Where's the vent? All my current vehicles seem to have a nice sealed bulb assembly (rubber boot covering it all).

Ford must have picked a crappy place for the vent then.


----------



## Alaric Darconville (Aug 4, 2021)

turbodog said:


> Really? Surprising. Where's the vent? All my current vehicles seem to have a nice sealed bulb assembly (rubber boot covering it all).


Very few are completely sealed, most will have venting areas that are not completely obvious. And the rubber boot 'sealing' the bulb to the lamp assembly will allow bidirectional air flow. If they were completely airtight, pressure changes from lamp heating/cooling could be a problem.

I don't have a picture immediately available, but on the '95 Previa's, each headlamp has tubelike projections on the rear of it, with a dense but permeable foam inside that tube, and a rubber cover with a duct on it to hold it that foam in and permitting bidirectional air flow. The foam keeps the spiders from exploring the lamp (and can stop small amounts of water from getting in so long as the lamp isn't submerged).


----------



## Autolamps (Aug 4, 2021)

John_Galt said:


> -Virgil- is envelope temperature something that is balance against the type/coverage area of blue tinting? Clearly the filtration effect will result in higher envelope temps, is this so specific to the area directly coated that manufacturers attempt to alter the envelope thickness under/immediately in contact with any coating, or is it such a small difference in lifespan that it would be a waste of time and money to thoroughly examine?


All glass envelopes are the same regardless if selective coated or not. Way too much detail to have different thicknesses for coated/uncoated products. Mass economy of scale for glass melts and tube tube manufacturing.


----------



## -Virgil- (Aug 4, 2021)

Kabana said:


> the next question which is the difference in offerings in the different brands +150 H4 lifespan (...) So what is Philips doing to get 400+hours vs Osram/Tungsram's 200- 250?



Most likely? Testing differently.



> We all know the end user would likely only get 1/2 to 2/3 of these lab test claimed hours.



That's not necessarily true. Actual bulb life can range from much shorter to much longer than published life figures. It depends on what voltage the car delivers to the bulbs, and other factors, too: is the voltage stable, or is it "dirty" (spiking up to high voltage momentarily, etc)? Are the headlamps on a soft-start and/or PWM circuit? Are the headlamps lit while the engine is being started and/or stopped?


----------

