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[Dave DND]

Not strictly an Omega question, but I`m having a play with LED`s and rear lights on my Beach Buggy at the moment, and this may even have some relevance.

Ok, tin of worms time I know, but just wondering what the official / unofficial line is from the MOT guys amongst you regarding LED rear lights -

I know the rules / regs regarding placement of lights and correct wattage bulbs of 21W flasher and 21W/5W for stop and tail, but many of the modern cars nowadays have LED rear lights instead that do not actually conform to these wattages. Although LED lights look bright, due to their efficiancy they run way under the power figures qouted for recommended wattages and I have never seen an MOT station measure the brightness output, so I just wondered if there were any guidelines as to what you would recommend for someone like me who is looking to build / convert a new rear set.

Does the number of led`s make a difference ? I know that there needs to be a brightness variation between tail ones and brake ones, or does it go on a percentage of bulbs showing between stop and tail ?

Roughly speaking, my plan is to go for around 30 medium intensity leds for tail with an additional 100 high intensity leds for brake, 50 high intensity for indicators, and 30 high intensity for reverse, (each side) within the original lenses.

Before you ask why not use the off the shelf LED conversion bulbs, well, its a fair question, but if you have ever tried some of those bulbs behind Classic Car lenses, you would have answered your own question.

They are pityfull - and in my mind bloody dangerous as they are often so dim.

The replacement stop / tail bulbs generally have a maximum of 24 or 36 leds, 30% of which don`t even point outwards, and the variation between tail and brake is not that good. On tail, there are usually only 9 bulbs running at 75% intensity, and when used behind a smoked lens can hardly be seen at all. From research I have done so far, Motorcycle plastics and modern plastics of lights lens`s seem to be a little thinner and allow light to pass through much more readily, wheras some of the older classic car lens are so thick, that even a filament bulb can often appear dim.

I tried fitting an LED replacement on one side and a 10 Watt bulb on the other and there was no difference - (I have tried both red and white LED bulbs for comparison) and surprisingly, the red bulb gave a slightly better light behind a red lens than the white one, but still wasn`t great.

If I am going to brake, then beleive me, people will see my brake lights !!

But it was this variation that got me wondering as to how they were "perceived" by the guys who make the decisions on the front line, ie: MOT testers. There must be a point where they think that it either isn`t bright enough, or the variation of intensity between tail and brake is insufficient?

So how would this be challenged or proven ? Or is it such an obscure problem that there is no real definative answer, and simply, "common sense rules"?

Any thoughts ?

 :-?

[RobG]

http://www.motuk.co.uk/manual/contents.htm

[TheBoy]

Without reading the MOT handbook, I guess the MOTers current just care if they work.  Apparently next year, the rules are stricter on many aspects.


What I have no idea about is what angle from the side do you need to see the lights, if any.

I suspect, like HIDs, there are no real laws, just a grey area because the EU allow them, the UK has to, without making proper, clear guidelines...

[Andy B]

Good question. 
How are you planning on fitting your leds behind the lenses?  :-/

[Kevin Wood]

I have a feeling the SVA/IVA manual (failing that the core construction and use specs) would be the place to look for the definitive information. From memory SVA/IVA certainly specifies the filament lamps of 21w or 5w but adds a get-out that they can be other types of "equivalent brightness".

At MOT, the tester will probably only consider if the lights are working and, subjectively, if the brightness is adequate. Having an MOT doesn't mean you are compliant with the C&U regs, though.

FWIW, a group of kit car owners to which I belong have made up a PCB with LED stop and tail lights which fits into a standard Caterham style light cluster. I will post some pictures if you're interested. IIRC, they had 30-40 red high intensity LEDs each, and a subset of these came on as tail lights, the whole lot with the brakes.

These have been in use on a dozen or so cars for a couple of years with no MOT issues that I'm aware of.

[Dave DND]

Good question. 
How are you planning on fitting your leds behind the lenses?  :-/

I have cut a sheet of acrylic to the same shape of the whole of the rear lens and the LEDS will mount to this. The sheet will then sit abot 2cm from the inside edge of the lens, so that the LEDS are very close to the plastic. This also enable me to retain the original bulb mounts so that I can revert back to filaments within minutes as the connections are made using old modified bulbs and simply plugged into the respective positions.

I`ll get some pictures up once I am happy with it.

 

[Dave DND]

I have a feeling the SVA/IVA manual (failing that the core construction and use specs) would be the place to look for the definitive information. From memory SVA/IVA certainly specifies the filament lamps of 21w or 5w but adds a get-out that they can be other types of "equivalent brightness".

At MOT, the tester will probably only consider if the lights are working and, subjectively, if the brightness is adequate. Having an MOT doesn't mean you are compliant with the C&U regs, though.

FWIW, a group of kit car owners to which I belong have made up a PCB with LED stop and tail lights which fits into a standard Caterham style light cluster. I will post some pictures if you're interested. IIRC, they had 30-40 red high intensity LEDs each, and a subset of these came on as tail lights, the whole lot with the brakes.

These have been in use on a dozen or so cars for a couple of years with no MOT issues that I'm aware of.

Thats the bit I`m thinking of - and to my knowledge, the testing centres do not have, nor use any light intensity measuring equipment - so is it really down to what the tester had for breakfast ?

[Kevin Wood]

Should have added, the SVA/IVA manuals also specify viewing angles and position of all lights.

[Dave DND]

http://www.motuk.co.uk/manual/contents.htm

Nothing is stated here about intensity of lights, nor how to measure brightness

 :-?

[Dave DND]

Should have added, the SVA/IVA manuals also specify viewing angles and position of all lights.

Placement of lights, (although a valid point) is not really an issue here, and as far as I can tell, the only guidelines are regarding the percentage of bulbs that must work before a unit is deemed to have failed and requires replacement.

Still not found anything relavent with regards to illumination intensity and LEDs

 :-/

[aaronjb]

FWIW, a group of kit car owners to which I belong have made up a PCB with LED stop and tail lights which fits into a standard Caterham style light cluster. I will post some pictures if you're interested. IIRC, they had 30-40 red high intensity LEDs each, and a subset of these came on as tail lights, the whole lot with the brakes.

Interesting, I was planning on doing the same thing for Lucas housings when I get to that point with the kit car (though I still need to order a chassis & body, first )

[Dave DND]

At MOT, the tester will probably only consider if the lights are working and, subjectively, if the brightness is adequate. Having an MOT doesn't mean you are compliant with the C&U regs, though.

True, but if challenged by the Feds, its usually an MOT centre that they will direct you to for a check. I suspect it would take considerably more before VOSA got involved for a tail light

 :-/

[Kevin Wood]

http://www.motuk.co.uk/manual/contents.htm

Nothing is stated here about intensity of lights, nor how to measure brightness

 :-?

I suppose the "inoperative, excessively damaged, deteriorated or obscured so that they are not visible from a reasonable distance" clause would  cover if the light was considered to be dangerously dim by the tester, but they certainly wouldn't measure it.

IVA manual states that "All lamps must emit light of an equivalent brightness and colour when compared to an "e" approved lamp of the same type". Since that's how a kit car gets onto the road, I take it to mean that it doesn't have to be incandescent or a recognised type of fitting but the inspector could compare it with an e marked fitting (and probably would, the pedantic b'stards ) and decide if it was too bright, too dim or equivalent.

True, but if challenged by the Feds, its usually an MOT centre that they will direct you to for a check. I suspect it would take considerably more before VOSA got involved for a tail light

Indeed. However, I'm always conscious that, whilst you can get away with all sorts of things, especially with a kit car, if a really serious incident happened, you could find yourself before the beak justifying your actions before an expert witness. :-/ OK, unlikely in the case of a light cluster, I agree.

Interesting, I was planning on doing the same thing for Lucas housings when I get to that point with the kit car (though I still need to order a chassis & body, first Grin)

I'll take some pictures of one when I get a chance.

Kevin

[aaronjb]

Indeed. However, I'm always conscious that, whilst you can get away with all sorts of things, especially with a kit car, if a really serious incident happened, you could find yourself before the beak justifying your actions before an expert witness. :-/ OK, unlikely in the case of a light cluster, I agree.

All it would take is a "I couldn't see his brake lights, Officer", I suppose

Still, as you say, probably unlikely.

I'll take some pictures of one when I get a chance.

Cheers Kevin LED lights, digital dash.. the folks on the Cobra Club will be apoplectic at my creation 

[Dave DND]

All it would take is a "I couldn't see his brake lights, Officer", I suppose

Somebody on another forum posted an interesting observation.

If you are unlucky enough to have suffered a rear end accident (Oo-er missus) the police can often determine if you were braking at the time by looking at any burnt out bulb filaments that have been subject to the atmosphere when the glass breaks -

Not something you could determine with LED`s

Food for thought I suppose ?
 :-/