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Author: Subject: LED headlights
ste

posted on 3/10/17 at 05:34 PM Reply With Quote
LED headlights

Just got these H4 LED bulbs off amazon for 15

I must say the light output is amazing

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prawnabie

posted on 3/10/17 at 06:46 PM Reply With Quote
I doubt the guy driving infront of you will say that!
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ste

posted on 3/10/17 at 09:55 PM Reply With Quote
I don't see the issue, i don't drive around with main beams on and the bulbs do not affect the beam pattern so I don't see an issue.
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MikeRJ

posted on 4/10/17 at 06:26 AM Reply With Quote
quote:
Originally posted by ste
I don't see the issue, i don't drive around with main beams on and the bulbs do not affect the beam pattern so I don't see an issue.


If true you would be owning the only set of H4 LED bulbs in existence that produce the same beam shape as a regular filament bulb. They ALL change the beam shape when installed in a reflector lamp, it's physically impossible for them not too since the shape of the light source is so different.

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Charlie C

posted on 4/10/17 at 06:34 AM Reply With Quote
Hi

As a lighting engineer I cant help myself and add my 2 pence worth.

Retro fitting LED bulbs will always change the light distribution because the light centres are entirely different even 1mm can make all the difference.
An LED has a very narrow beam of distribution so generally the retro fit LED bulbs have a number of LED's pointing in different directions to mimic the filament on a standard bulb but this results in multiple light centres in multiple locations.

A filament bulb has an approximate 5mm filament perpendicular to the base with light emitting in all directions, the head light is designed around a filament bulb and any change in photometric centre will alter the beam, even upgrading the bulb to a high performance filament bulb effects to beam because it move the centre further forward.

If your checking the beam angle against a wall you probably wont see any difference and you wont be able to compare the light intensity percentage difference at different locations in the beam.

What the main difference with upgrading filament and LED bulbs is the light is much bluer so in appears to be brighter, I wont go into the science but humans have evolved to see light with a blue hue to be bright than white (that's how washing powders work). The problem with this is to produce blue hue light especially with LED's the spectrum of light is significantly reduced so less colour can be seen, and as the centre of our vision is based no colour not contrast we actually interpret less visual information with a reduce spectrum light source (blue hue light) even though it is producing more light.

When looking a lighting its not just the output which is important it is also the spectrum of light, this is why for true colour rendering filament lights are the best because they produce full spectrum of light even the wave lengths we can see, but this is very wasteful in terms of energy consumption.

The best way to convert to LED head lights it to buy a purpose built LED head light.

I know this is very techy and it probably doesn't make a massive difference in the real world.

Just as a side not there are some serious long term health issues with blue light LED's known as Cool White which might see the use band in the future when it starts costing the NHS a lot of money, its to do with sleep (circadian rhythm).

[Edited on 4/10/17 by Charlie C]

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ElmrPhD

posted on 4/10/17 at 07:25 AM Reply With Quote
Wow! Thanks for the excellent information Charlie C!!!
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Paul_Arion

posted on 4/10/17 at 01:52 PM Reply With Quote
quote:
Originally posted by MikeRJ
quote:
Originally posted by ste
I don't see the issue, i don't drive around with main beams on and the bulbs do not affect the beam pattern so I don't see an issue.


If true you would be owning the only set of H4 LED bulbs in existence that produce the same beam shape as a regular filament bulb. They ALL change the beam shape when installed in a reflector lamp, it's physically impossible for them not too since the shape of the light source is so different.


As above - not such an issue for Main Beam but H4 is a twin filament bulb and so the dipped beam pattern will undoubtedly be affected. Be interesting to see if it passes an MOT with the new LED bulbs in

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loggyboy

posted on 4/10/17 at 02:11 PM Reply With Quote
Whilst I agree with the above on it changing the position of the patter, - the pattern itself of a UK lens is fairly straight forward, it flat with a kick, so even if these LEDs bulbs do change the position of the pattern, its only a matter of moving the lens to suit the new position.
Doing a wall check at a reasonable (or multiple) distances should be more than adequate.






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dinosaurjuice

posted on 5/10/17 at 07:46 AM Reply With Quote
The owner of my local MOT station has aftermarket fan cooled LED H4 bulbs in his old Pajero. Might be pot luck but the beam pattern is perfect
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rusty nuts

posted on 5/10/17 at 04:42 PM Reply With Quote
The last edition of CKC has an excellent article covering this subject
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Mash

posted on 15/11/17 at 06:09 PM Reply With Quote
Hmmm, interesting, wish I'd read all this first, just bought some of these for my Transit

Nighteyes

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Mr Whippy

posted on 16/11/17 at 07:03 AM Reply With Quote
quote:
Originally posted by Mash
Hmmm, interesting, wish I'd read all this first, just bought some of these for my Transit

Nighteyes


tbh I looked into this just last month and none of the LED replacement bulbs were legal in the UK on any exterior lights, even if you managed to get through the MOT you could still be done and dazzle other road users, worse is they are so obviously LEDS due their colour and behaviour. In crashes the police do check the bulbs fitted to the car.

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