Efficiency of various light sources

Submitted: Friday, Jan 14, 2005 at 15:12
ThreadID: 19367 Views:2353 Replies:5 FollowUps:2
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Hi all,

There has been discussion recently about use of LED lights.

I have come across a useful site which has a wealth of info about all types of lighting systems.

Amongst some of the useful info I found is data on efficiency of various types of light.
240v incandescent 17 lumen/watt
12v halogen 21 lumen/watt
White white LED 33 lumen/watt 2004 data. Improvement expected in 2005
Compact Flouro 45-60 lumen/watt
32W T8 tube flouro 80 lumen/watt

As can be seen LEDs still have a long way to go to equal the efficiency of flouros

Interestingly the spectrum of flouros and white LEDs better matches the response of the human eye in low light conditions so the gain over incandescent lights is even greater in other than bright light.

Phil I

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Reply By: Member - Hugh (WA) - Friday, Jan 14, 2005 at 15:45

Friday, Jan 14, 2005 at 15:45
Hi Phil,

Interestingly, I was reading an article this morning in Dec issue Automotive Engineering Int'l on vehicle lighting systems. There was a 50% increase in use of LEDs for rear lamp applications last year (3% of market), expected to increase by 150% this year. OEMs are experimenting with white LEDs for exterior applications, with headlights featuring white LEDs expected to enter market in 2008 and higher volumes expected post 2010. Current factors limiting forward lighting application being cost, luminous flux and ability to operate and elevated temps (125'C). There are active programs to overcome these issues so I guess we'll being seeing these around in a few years time.

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Reply By: Member - Sparkie (QLD) - Friday, Jan 14, 2005 at 19:31

Friday, Jan 14, 2005 at 19:31
For the amount of power LED's use that isn't a bad figure. also there are usually more than one LED per light so it should increase its output accordingly and with less heat they use less power which is also a good thing. I am not saying fluro's are terrible but the humble LED has come a long way and who knows, soon we may all use LED's to light all our houses and street lights.

This is all just speculation by myself and should not be taken as the truth or gospel.

Sparkie(IE not Y) ;-)
AnswerID: 93120

Reply By: MaxMod - Friday, Jan 14, 2005 at 22:57

Friday, Jan 14, 2005 at 22:57
The real benefit of LEDs is where you want the light focussed in one direction, because that's inhrently the way they work without needing a reflector - that's why they're popular for torches and tail lights.

The biggest LED available today is 5 watts, but it's pretty expensive.

Halogen efficiency depends very much on how hard you drive them - consider that a 50watt downlight is rated at 50watts at 11.3 volts - apply 14 volts in a car and it will be a lot more efficient, but it may only last 20 hours.
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Reply By: porlsprado - Friday, Jan 14, 2005 at 23:52

Friday, Jan 14, 2005 at 23:52
i may not know what i am talking about so this is for interest sake only. LED's,i love them my current favourite torch is a 5 LED hand held that works off 2 x 3v batteries that has a wide spectrum rather than a narrow spectrum. But the wide is sensational, its an inova X5 or something like that. I also have some lights i bought for football training cause our field did not have lights over the other side. 2x2 x 24w flouros in a very reflective casing. They are exellent but i could not in the long term be bothered organising power to them. But one light is effectively the equivalent, and i have compared and do beleive, the same as a 500w incandescent bulb. Thing is, being 2 x 12v 24w bulbs i'd love to run them off 12v but upon enquiry a friend advises me a flouro needs 350v to start so i would need to deal with a number of transformer issues and not one. Point is these flouros are better than any LED i have seen but the power consumption of the LED torch for brightness is better than any incandescent torch i have.
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Follow Up By: porlsprado - Friday, Jan 14, 2005 at 23:53

Friday, Jan 14, 2005 at 23:53
I've had a few beers tonight so i hope that makes sense.
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Reply By: Noosa Bushtrackers - Saturday, Jan 15, 2005 at 16:25

Saturday, Jan 15, 2005 at 16:25
We replaced the globes in our caravan reading lights, with 21 LED globes and now instead of having a lot of heat produced using 3amps per light, we now have No heat and only use 0.1amps per light.

The LED do not give a wide area of light, and from a distance you wouldn't think you could read under them, but when under them they give a brilliant white light that makes reading very easy. They are really the way to go in a caravan situation where you are running off batteries and solar power.

I am now looking around for something like an LED reversing light with about 60 LEDs so that I can replace the exterior light with one or 2 of these.
Doing it tuff, Towing a Bushtracker.

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Follow Up By: Bob Y. - Qld - Sunday, Jan 16, 2005 at 12:55

Sunday, Jan 16, 2005 at 12:55

Have a look at January edition of Silicon Chip mag. They have a article about a 48 LED "prawn light", that with modification, may work as a reversing light.

Seen it all, Done it all.
Can't remember most of it.

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