Has LED lighting efficiency reached a limit?

[Andy Burns]

Not so sure, last car was HID, current one is LED and noticeably better illumination, to my eyes at least ...

[Pancho]

If that is the case it is a bit surprising so many modern downlights don't have replaceable bulbs. I doubt many people want to rewire a new downlight every five years as opposed to just replacing a £2 gu10 bulb.

[The Natural Philosopher]

You completely misundersand me. What I mean is that double the lumens doesn't look a whole lot brighter So in practice 100lm/W -> 200lm/W is not a giant difference asfar as human perception goes

[The Natural Philosopher]

Allright f****ng pedant. Human perception off lumens is pretty logarithmic.

It is not.If double the efficiency doesn't look that much brighter, who cares whether its 100lm/W or 200lm/W?

so about "5db brighter" or a stop and a half on a camera lens

[Caecilius]

It's an easy job if the original installation left enough slack in the cables to pull the lamp and transformer through the hole.

The only potential problem I find is that the edge of the hole in the plasterboard ceiling is fragile, and can be easily damaged by the retaining clips as the lamp is removed and replaced.

[tabbypurr]

Consumer devices that are stupidity incarnate surprise you?

NT

[Chris Green]

The person paying the electricity bills!

Keep the brightness the same and use half the electricity, surely that's why we're using LEDs instead of filament bulbs to start with.

[polygonum_on_google]

I drive two cars on a very regular basis.

The LED one has a very even beam pattern. (And it switches on side illumination when going round corners.) Which makes it very pleasant to drive at night. Full beam is excellent.

The other car, not 100% sure of the technology, but more recent than the LED car, has very bright headlamps. But they are less even. Brighter in the middle and fading to the edges. Perfectly acceptable and, had I not got an LED car for comparison, I might be raving at them being the best headlamps I have ever had.

[Tim Lamb]

I must try not to be annoyed when you come over the brow of a hill towards me:-)

[polygonum_on_google]

The non-LED one has automatic dip/full. The LED one doesn't. But I try to be considerate. :-)

[Andy Burns]

People used to flash me more with the HID headlights (when on dipped) than with LEDs, both are self-levelling, so I'd say the LEDs must have a better beam shape.

[polygonum_on_google]

Agreed.

[Dave Plowman (News)]

There are different types of headlights and power of HID. The point I was making (having recently done tests) is the very best aftermarket LEDs - costing about £120 a pair - can't match the output of 55W HID.

[Dave Plowman (News)]

There are lots of different headlight designs.

The type that gives the most even illumination across its beam is the projector type - with a bull's eye on the front. But also has an extremely sharp cut-off. Which may, or may not be, what you like.

Other beauty of that design is you get much the same beam pattern regardless of bulb type used - halogen, LED or HID. Unlike some more conventional lamp designs where the beam pattern goes all to c*ck with a different type of bulb. And can dazzle others if a different type is tried.

[Dave Plowman (News)]

All down to how well the lamp unit (reflector etc) is designed/matched to the light source. And some are very much better than others.

[NY]

I agree about the extra side illumination of HID lights when turning: very useful. Do HID cars tend to keep the HIDs lit when the beam lights are lit? I presume they do, because HIDs don't like to be turned on and off frequently; by the same token, I presume that full beam lights are still filament (or other technology that can be turned on and off frequently).

The problem is that headlights can be wonderfully bright and even, but if they have to point down and to the left (dipped) whenever there is a car ahead or oncoming, then they are still as crippled as if they were filament bulbs. It is a very unnerving feeling to be driving on full beam, able to see a good distance along the road, and then to have to adjust to seeing less far ahead when a car comes into view and I have to dip the lights.

[Andy Burns]

I think swapping between dipped/full beam is a case of moving an internal "flag"

[NY]

Ah, so it's the same bulb but moved relative to the reflector/lens (or shaded differently, hence you use of the word "flag"). I'd assumed it was two separate bulbs and reflectors, as with cars that use two single-filament tungsten bulbs and reflectors to alternate between dipped and full. Interesting that older cars with tungsten bulbs tend to use a single reflector with a twin-filament bulb whereas newer ones have two totally separate single-filament bulbs and reflectors; is that differences in aesthetics and design or is it different regulations?

Is there any rule about whether cars must *alternate* between two bulbs/filaments/reflectors, or whether they are allowed to keep the dipped lights illuminated when the full beam is additionally turned on? Some cars alternate, some leave the dipped on when the full beam is on.

[Tim Streater]

Is this how they can have headlights which adjust between left and right hand driving?

[Andy Burns]

Yes, previous car had that option.