help with working out LED’s candelas in to lumens

[mollydog]

I’m planing on replacing my front orange indicators for those clear ones and in the process also replace the 21 watts indicator bulb for those white DRL to orange indicator LED’s so the indicator housing has two uses


these LED’s

in the smoked housing

the ones I bought (not fitted yet) test out OK but in good daylight they are barely visible, in night time they are more than bright enough (when you don’t really need them)

what I discovered on the government web site is these DRL’s according to the regulations on the daytime running lamps, the light intensity should be between 400 and 800 candelas.

that’s fine, but so far I’ve only seen sellers advertise these DRL LED’s in lumens, the ones I have are only About 250LM and 3 watts and a ocular temp 5500-6000K, so not blue a some I see are

I find that 1 candela = 12.57 lumens but discovered these two light measurements can’t really be converted due to how each measures light. one thing’s for sure, in good daylight my 250LM and 3 watts ones I have are not much use

I have now found others, one set is stated as being 924LM with a ocular temp of 6000K and 16 watts

another (from Amazon) is stated as being 1188Lm, 16.2 watts and colour temp 6000K

then another on Amazon with 1530Lm. 3.6 watts but with a colour temp of approx 8000K

you can see why I’m slightly lost, any help would be most welcome

 

[Nigel]

I don't expect there is a good answer due to the way the light is spread over a large area and diffused rather than focused like many LEDs, you don't have a bright spot in the middle of the bulb like the rules were written for. The rules are not really a problem since you only need to get it passed the MOT tester, and he will have no way of testing the actual light output, and he doesn't need to check it is within the rules anyway, only that in his opinion it is working, so if it looks good to you, then it probably does to him and there will be no problem. If it looks useless to you, then it will to him too.

Above all, you want it to be safe, and for that, for an indicator, the brighter the better, within reason.

250LM would be OK if it was a small bulb with the light concentrated in the centre, I can believe it's not good for those. I'm not sure what size they are from the photos, but 1530Lm seems a bit excessive for the function, also I would find the 8000K undesirable, I think that is the boy racer version!

The other two, you probably won't be able to see the difference unless one has better diffusion or something.


Interested to see what they look like fitted...

 

[mollydog]

Lotus had orange indicators as standard on the Elise S1, then on the Elise S1 135 and the 160 (maybe others too) for the front they had clear lens for the indicators



these clear lens were low volume production and have been out of production for a good many years so second hand ones were selling for around £400 for two

then a guy in Canada has started producing these @£72 for two





I like many others with Elise S1’s, have ordered a set, not yet arrived but shouldn’t be ing now

the one I’ve tested my ring light LED’s on is a smoked lens made by someone on the Elise forum and was planing on using these, but the light produced by the LED’s I have just are too weak in daylight to be of any use



I’m tempted to get the nightlight LED off Amazon the one calmed to have a lumens of 900 and see how that works out, as for sure my DRL with a calmed 250 lumens isn’t bright with the smoked lens

 

[SawMaster]

Get a warmer temp, 8000K will be very glarish and garish too; 6000K will be much more pleasing and ~1K lumens should be quite visible daytime. If you have any problems it will probably be supplying the needed wattage- can your car's wiring and lighting circuits handle that? Sorry but my lumens integrating sphere cannot handle that diameter and I doubt that you'll happen across anyone else who has even this much equipment, so don't worry about the legality as long as they look about as you'd expect.

Phil

 

[Nigel]

I imagine you are losing half the light with that smoked lens, even if it doesn't really look like it. If you have a camera which will show the exposure properly then you can do a comparison to check.

That Canadian lens looks nice, high quality plastic?
I'm surprised the Canadians have Lotus Elises! They only seem to have USA vehicles.

 

[mollydog]

I know the few Elise S1’s in America were only able to be used on private roads as they weren’t federalised for public roads, only now that some Elise S1’s are reaching the age 25 years, making them exempt from having to be federalised

I’ve seen an add from a guy in America looking for a MY1995/6 Elise to use on American roads

maybe not so in Canada, the guy who’s making these lens’s is also a member on the Elise forum and owns an Elise S1