XC70 LED Bulbs (reflector) ?

[Tatsfield]

I've never understood why the main beam regulations concerning the fitting of LED or HID bulbs would worry about blinding oncoming drivers. All main beams if not dipped when approaching other cars will blind oncoming drivers so the technicalities of the way they do it is irrelevant and they can be dipped. I can see that dipped beams should not blind and if they do, the modification should not be carried out on the dipped beams but there is a certain amount of suck it and see involved and testing the modification to ensure it is safe but not relying on it to pass the MoT would seem a sensible approach as dim lights can be dangerous on country roads.

What I still do not really understand is why LED bulbs are any different to incandescent ones apart from being brighter and what it is about them that poses a blinding risk if the lights are properly adjusted. On a previous car I was able to fit HID bulbs as the car just scraped by on the necessary requirements of projection housing, headlight washers and in-cabin beam height adjustment. I don't think that Halogen bulb fittings on Volvos meet all three of these requirements for LED/HID upgrading.

[Clan]

Originally Posted by Tatsfield

I've never understood why the main beam regulations concerning the fitting of LED or HID bulbs would worry about blinding oncoming drivers. All main beams if not dipped when approaching other cars will blind oncoming drivers so the technicalities of the way they do it is irrelevant and they can be dipped. I can see that dipped beams should not blind and if they do, the modification should not be carried out on the dipped beams but there is a certain amount of suck it and see involved and testing the modification to ensure it is safe but not relying on it to pass the MoT would seem a sensible approach as dim lights can be dangerous on country roads.

What I still do not really understand is why LED bulbs are any different to incandescent ones apart from being brighter and what it is about them that poses a blinding risk if the lights are properly adjusted. On a previous car I was able to fit HID bulbs as the car just scraped by on the necessary requirements of projection housing, headlight washers and in-cabin beam height adjustment. I don't think that Halogen bulb fittings on Volvos meet all three of these requirements for LED/HID upgrading.

Think about the filament of the H7 bulb ,it is critically placed and aligned in the bulb to work with the reflector which itself is designed to work with the H7 bulb. The filament emits light in all directions equally from the filament along it's length.

A LED cannot do this when you think about it, that is why you get dark patches on the road and unwanted light going to the wrong places in front of you at night. The LED makers did their best to get it to work but LEDs emit light straight out from one plane NOT 360 degrees around like a filament does. I have tried several LED H7 bulbs over the last 10 years and scrapped them before they came illegal Because they were inferior , too bright in the wrong places and too dull in the places you needed them.

Todays modern LED Headlamps are a completely different design with multiple LED units in each headlamp and a number of specifically shaped mini reflectors used to do the job a simple H7 and reflector does.

[al dm]

Originally Posted by Clan

Think about the filament of the H7 bulb ,it is critically placed and aligned in the bulb to work with the reflector which itself is designed to work with the H7 bulb. The filament emits light in all directions equally from the filament along it's length.

A LED cannot do this when you think about it, that is why you get dark patches on the road and unwanted light going to the wrong places in front of you at night. The LED makers did their best to get it to work but LEDs emit light straight out from one plane NOT 360 degrees around like a filament does. I have tried several LED H7 bulbs over the last 10 years and scrapped them before they came illegal Because they were inferior , too bright in the wrong places and too dull in the places you needed them.

Todays modern LED Headlamps are a completely different design with multiple LED units in each headlamp and a number of specifically shaped mini reflectors used to do the job a simple H7 and reflector does.

Well, yes and no. An LED doesn't emit only in one plane. If it did, it would be a laser. LEDs have a fairly wide emission angle, but the luminous flux does drop off pretty quickly as the angle gets wider.

Modern LED headlight bulbs try hard co compensate for this by using multiple LEDs at different angles or putting lenses over the emitter to spread the light.

The Philips ones I mentioned above even appear to have a little reflector built over one of the LEDs on each side to try and compensate for this. So hopefully, with a little bit of decent R&D behind things, an LED based headlight bulb will throw light more or less 360 degrees. There will almost certainly be areas that are significantly different in luminosity though - it's consistency of that luminous flux through 360 degrees that is difficult.

The distance of the light emitters from the base of the bulb is super easy to make exactly the same as that of a halogen bulb. A millimetre or two here wont make much difference either.

All that said, the problem is basically what you stated. I have also had crappy LED bulbs in the past, and got rid of them.

Will the Philips bulbs be any better? I hope so, but the true test will be what the beam pattern actually looks like when fitted.

[Tannaton]

Originally Posted by al dm

Well, yes and no. An LED doesn't emit only in one plane. If it did, it would be a laser. LEDs have a fairly wide emission angle, but the luminous flux does drop off pretty quickly as the angle gets wider.

Modern LED headlight bulbs try hard co compensate for this by using multiple LEDs at different angles or putting lenses over the emitter to spread the light.

The Philips ones I mentioned above even appear to have a little reflector built over one of the LEDs on each side to try and compensate for this. So hopefully, with a little bit of decent R&D behind things, an LED based headlight bulb will throw light more or less 360 degrees. There will almost certainly be areas that are significantly different in luminosity though - it's consistency of that luminous flux through 360 degrees that is difficult.

The distance of the light emitters from the base of the bulb is super easy to make exactly the same as that of a halogen bulb. A millimetre or two here wont make much difference either.

All that said, the problem is basically what you stated. I have also had crappy LED bulbs in the past, and got rid of them.

Will the Philips bulbs be any better? I hope so, but the true test will be what the beam pattern actually looks like when fitted.

The main point is that traditional car headlamps designed for both HID and Halogen bulbs, reflector or projector, are designed around the principle of a "point source" of light - i.e. there is a filament or discharge tube which is of a very specific shape, size and placement that throws light evenly through 360 degrees. LED lamps of such a small format can never do this, and hence only really work in optical systems designed for LED. To get to the level of light output, even the best LED lamps need multiple emitters and hence are in different places and yes the odd millimeter does make a difference.

For precise optics and beam control, the point source of light needs to be very small, a H7 filament us around 1mm wide and 5mm long. A diode of this size could never produce nearly enough light and a diode large enough could not be precisely controlled optically which is why all modern cars with LED headlamps have many, small "luminaires" to make up the headlamp itself.

They're literally a square peg in a round hole when retrofitted to replace halogen lamps, you have a much higher chance of success with a HID retrofit which can re-create a point source.

[monkeh]

I'll come out of the closet here with my findings, I know there'll be some Reeeeeeeeeeeeee's about hid in halogen housings,
Clan, you are 100% right, leds need to be set up so that they shine on the bits of the housing to direct the light to where it should be.
I bought a set to try out (nighteye ebay jobbies)
Scatter was horrific, pre set up, post set up was better, but still had horrible scatter in places that I was really unhappy with.
Back to nightbreakers, until...
I found out about h7r type lamps for hid systems.
I've ran them the past few days, as I work shifts, night time has always been available. Cutoff is good, with zero scatter or stray light standard h7 hid lamps show.
There are shields on these particular lamps that eliminate that annoying glare/scatter/stray beams.

In fairness, I'm impressed with them, but at £55 a pop, not cheap. I'm waiting for Al's report on the Philips leds.

I will say I'm totally against what I've done, I've always retrofitted projectors to vehicles before adding hid to them, hell, I've ground the fluting off a 940 glass to fit projectors. But these lamps appear to be good. Naturally, the first flash I get, out they come. Back to Osram.

[Tannaton]

Originally Posted by monkeh

I'll come out of the closet here with my findings, I know there'll be some Reeeeeeeeeeeeee's about hid in halogen housings,
Clan, you are 100% right, leds need to be set up so that they shine on the bits of the housing to direct the light to where it should be.
I bought a set to try out (nighteye ebay jobbies)
Scatter was horrific, pre set up, post set up was better, but still had horrible scatter in places that I was really unhappy with.
Back to nightbreakers, until...
I found out about h7r type lamps for hid systems.
I've ran them the past few days, as I work shifts, night time has always been available. Cutoff is good, with zero scatter or stray light standard h7 hid lamps show.
There are shields on these particular lamps that eliminate that annoying glare/scatter/stray beams.

In fairness, I'm impressed with them, but at £55 a pop, not cheap. I'm waiting for Al's report on the Philips leds.

I once fitted H7 retrofit HID's into a V50 using new Bi-Xenon projector assemblies (the originals were cloudy and could not be cleaned). It worked very well and produced a very good beam pattern with the correct cut-off and I had Bi-Xenon as well as the halogen main beam. Huge improvement over the old, faded factory lamps. Though sadly not legal now (did it around 2011). I would share a link to the write-up I did but photobucket closed my account so no pics now.

EDIT: It's here : https://www.volvoforums.org.uk/showthread.php?t=262911

[monkeh]

Originally Posted by Tannaton

I once fitted H7 retrofit HID's into a V50 using new Bi-Xenon projector assemblies (the originals were cloudy and could not be cleaned). It worked very well and produced a very good beam pattern with the correct cut-off and I had Bi-Xenon as well as the halogen main beam. Huge improvement over the old, faded factory lamps. Though sadly not legal now (did it around 2011). I would share a link to the write-up I did but photobucket closed my account so no pics now.

EDIT: It's here : https://www.volvoforums.org.uk/showthread.php?t=262911

I ordered upgraded projectors too, for my chrysler, with valeo projectors that are known to be utter arse.
It's quite enjoyable to upgrade something that looks totally stock but works night and day difference. I remember reading where I bought the projectors from that the scv's series of volvo had poor projectors.

Its actually quite nice here we can have a good discussion without the big red finger of "YOU'RE BREAKING THE LAW".
Refreshing!

[al dm]

Originally Posted by Tannaton

The main point is that traditional car headlamps designed for both HID and Halogen bulbs, reflector or projector, are designed around the principle of a "point source" of light - i.e. there is a filament or discharge tube which is of a very specific shape, size and placement that throws light evenly through 360 degrees. LED lamps of such a small format can never do this, and hence only really work in optical systems designed for LED. To get to the level of light output, even the best LED lamps need multiple emitters and hence are in different places and yes the odd millimeter does make a difference.

For precise optics and beam control, the point source of light needs to be very small, a H7 filament us around 1mm wide and 5mm long. A diode of this size could never produce nearly enough light and a diode large enough could not be precisely controlled optically which is why all modern cars with LED headlamps have many, small "luminaires" to make up the headlamp itself.

They're literally a square peg in a round hole when retrofitted to replace halogen lamps, you have a much higher chance of success with a HID retrofit which can re-create a point source.

I'm not trying to argue with you here, just engaging in some science pedantry...and thought experiments...

A Halogen bulb filament is not a point source. As you say yourself, it's somewhere in the 1mm x 5mm range. I can't really speak from experience for the actual emitting area of a HID bulb either, but I can pretty much guarantee that it's not a point source either - more likely to be an egg type shape with luminous flux dropping off significantly away from the centre. I don't know. But anyway, not a point source.

And Halogens certainly don't throw light through 360 degrees as there will always be a shadow area from the filament support structure. Similar for HID - although that support structure looks to be wider, so there will be more shadow. That said, the shadow area is designed in in the reflector/projector housing design.

Looking at automotive type LED chips, the Lumileds Altinon TopContact LEDs have a viewing angle of 120 degrees with 90% luminous flux. So theoretically, if you had three of these spaced 120 degrees apart, you would have a 360 degree light output with at least 90% of the luminous flux available everywhere in the 360 degrees.

This seems pretty simple to do - mount them on a triangular substrate with 120 degree internal angles. But most modern LED headlight bulbs seem to only have two mounting faces for the LEDs - 180 degrees apart. This is probably due to ease of manufacture. The SMT lines that assemble this kind of stuff prefer to have a distinct top and bottom side to attach chips to.

So - now let's say we have two sides, each with a light cone of 120 degrees. That gives us 240 degrees light coverage. So we still miss 120 degrees for the full 360 degrees.

What if we then mount two emitters on each side, each offset by 30 degrees. We could do this with lenses, reflectors or even physical orientation of the emitters. That should give us a full 360 degree coverage within 90% of maximum light output. Theoretically only. Of course there will be some degree of shadowing from things like the wire bonds onto the LEDs themselves and the design of the heatsink perhaps if poorly done.

Now, looking at the aforementioned Lumileds Altinon LED, in its 1*4 emitter configuration, the light emitting area is 1.5mm x 4.3mm (pretty close to an H7 filament, right?) and that area kicks out a nominal 1200 lumens or so. That is (to use a technical term) a metric crapload of light - and way higher than the equivalent light emitting area of a halogen filament. Compared to an HID device, I don't know the answer.

Anyway, now put 4 of these devices into an H7 compatible format, 2 per side of the substrate and use substrate geometry and lenses/reflectors to spread the light to as close to 360 degrees as you can get while still being reasonably easy to manufacture and theoretically you should have a very powerful and somewhat balanced luminaire throughout the 360 degrees. Not perfect, but possibly pretty good.

Bottom line, the physics/engineering kind of supports cleverly designed LED replacement bulbs being able to vaguely reproduce the emitting area of a halogen bulb, but with a whole load more luminous flux available.

Admittedly, it's much easier to use these powerful automotive specific LED chips in matrix type applications with individual reflectors per chip. But it's not without the realms of possibility to design something that would work relatively well to replace a standard H7 Halogen within roughly the same size envelope.

Would it work well for every car? Certainly not as different manufacturers have different reflector configurations, so it will always be a case of "suck it and see", but I certainly can't see any reason for dismissing LED replacement bulbs in Halogen reflectors. So far, most results haven't been great, but most products have also been cheap ass cobbled together Chinese efforts with no real R&D behind them.

Anyway, food for thought...

[Tannaton]

Whilst I’m sceptical your LED swap out will be completely successful, it’s good to see someone doing a lot of reading about it and digesting the input from other contributors. I do wish you luck with it - let us know how it goes…

[al dm]

Originally Posted by Tannaton

Whilst I’m sceptical your LED swap out will be completely successful, it’s good to see someone doing a lot of reading about it and digesting the input from other contributors. I do wish you luck with it - let us know how it goes…

:-) I am sceptical as well. But as I am not happy with Halogen in the days of LEDs, let's see what happens!