kermit_rr said:

a good read on the different colour temps

Best LED Headlight Color Temperature for Night Driving: 4300K vs. 5800K vs. 6500K

When it comes to upgrading your vehicle's headlights, LED technology has revolutionized the market, offering superior illumination, energy efficiency, and longevity compared to traditional halogen bulbs. However, with the various color temperature options available, such as 4300K, 5800K, and...

suparee.com

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Datatek said:

Longevity? Not likely with LED's, they will not match the life of the tungsten bulbs in my P38 which are 25 years old or the ones in my MR2 which are 38 years old.

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Mark Piercy said:

But us blokes can't find stuff in a cupboard

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Datatek said:

Longevity? Not likely with LED's, they will not match the life of the tungsten bulbs in my P38 which are 25 years old or the ones in my MR2 which are 38 years old.

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Graculus said:

Actually, LED's will last longer than the tungsten or tungsten-halogen equivalent in the same vehicle as they don't suffer from increased filament shedding due to raised system voltage. Other variables are of course vibration and the percentage of use per time period. As mentioned above (and also relevant to filament lamps) the initial quality has a large bearing upon longevity.

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Datatek said:

Not in my experience. Light output also degrades over time.

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Graculus said:

Then you're looking in the wrong cupboard!

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Graculus said:

We have different experiences of the same thing then. 'Xenon' lighting does indeed over time but I've not seen any cases of LED lighting - certainly not 'branded' or OEM LED's degrading in output - unless you mean 'no output at all' which is 100% degraded... In most cases it's caused by collision damage allowing water into the lighting assembly.
Tungsten filament lighting also degrades over time - as I'm sure you know. The tungsten filament 'sheds' particles which end up on the glass envelope, which is the dark coating you get on old filament lamps, often dimming the visible output enough to cause it to be insufficient to pass an MoT test, particularly on 5W sidelights - you'll also notice it on 21W (or 21/5W combination lamps) brake lights where the driver has a habit of holding the car on the brakes excessively.

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Graculus said:

We have different experiences of the same thing then. 'Xenon' lighting does indeed over time but I've not seen any cases of LED lighting - certainly not 'branded' or OEM LED's degrading in output - unless you mean 'no output at all' which is 100% degraded... In most cases it's caused by collision damage allowing water into the lighting assembly.
Tungsten filament lighting also degrades over time - as I'm sure you know. The tungsten filament 'sheds' particles which end up on the glass envelope, which is the dark coating you get on old filament lamps, often dimming the visible output enough to cause it to be insufficient to pass an MoT test, particularly on 5W sidelights - you'll also notice it on 21W (or 21/5W combination lamps) brake lights where the driver has a habit of holding the car on the brakes excessively.

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Mark Piercy said:

You are

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Datatek said:

On the ones I have looked at, the high brightness is obtained by pulsing the Led's with a duty cycle of around 50% which allows the LED's to be run at higher voltage with cooling in the off period. Mostly it is the electronics that fail. LED lights age over time and progressively get dimmer until they stop working altogether. This is what we call “lumen degradation” or “LED degradation”

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Graculus said:

As above, overdriven LED's will have a shorter life and age quicker, but the ageing phenomenon isn't as marked as you'd have us think - the first link when searching for 'LED degredation' is this one, which suggests, all things being equal, that it's pretty much a non-issue. https://lamphq.com/led-degradation/ Of course, the 'buy cheap, buy twice' LED's will have more issues with control electronics, that's not the sort of equipment I work with or buy for myself though - possibly why LED degradation isn't a factor I've ever had to learn about or be troubled with.

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Datatek said:

As I said all LED's degrade over time, I did not specify a time scale. In most cases it's the electronics that fail rather than the many individual LED's that make up the lamp.
From your link:- After purchasing an LED lamp usually has the brightness specified by the manufacturer. Over time, the luminosity slowly decreases and the lamp becomes darker. By the way, this effect also occurs with old incandescent and halogen lamps and especially with energy-saving lamps.
after just a few thousand hours. At the end of the life expectancy the filament breaks and the lamp remains dark. Such a sudden defect cannot occur with LEDs. This is pure marketing bull****, LED lamps can and do fail instantly, as I said due to failure of the electronics.

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AndyF07 said:

Well today started stripping down my lovely 2002 4.0 P38 to replace the head gasket due to a small oil leak. After 165k miles a bit of tic that is well deserved. Bad light stopped play for today (shame the clocks went back) but think I found the leak Upwards and onward tomorrow.....
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Scotiawhiskers said:

Having done similar on Otto the first year we had him, can recommend green gunk or autoglym engine and parts cleaner, effective and much less toxic. Also replacing head bolts with a stud kit, torque to 25lbft, leave overnight, torque to 50lbft, can then go straight to 70, no detectable extra movement over 50. No stress about angles or stripping threads.

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