LED Lighting

Hi all.

I was looking at an article in DIY-Boat about lighting and it seemed to relegate LED lighting to specific use scenarios instead of as a general purpose light source.

I'm not sure as to the date on the article (it's actually part of their articles on CD set), but it talked about a lot of different LED lighting options, so I would imagine it was fairly recent.

The question is, has LED lighting not come far enough to replace general light sources? In doing research on LED lighting, it looked like a lot of the latest generation LED lights were fairly useful for all sorts of general lighting uses, but that could just be marketing.

-b

Hi Bryanc, welcome to the forum are you asking out of environmental concerns? what else could possibly be the preference for LED lighting?

it's the most efficient lighting source there is. so the light you get for the power you put in is nuts. 0% heat loss. 100% happy electrons.

in other words, it's the light source with the least amount of current draw.

Post edited by: bryanc, at: 2007/10/17 09:48

What do you think is holding up the spreading of this technology in widespread commercial use?

I can't speak to this from personal experience, but i've posted the same question on other forums and so far the answer has been that the lighting is not as warm in color as traditional lighting technologies, and the diffuser technology has not come far enough to be as soft as other lighting technologies. However, there is a company called IMTRA (www.imtra.com) and one poster says that their lights solve those two issues. however, i haven't seen the IMTRA stuff in person, so i can't speak to it.

It thus needs more publicity if so (the tech imtra uses).

Now I've grown curious

I am in the process of trying to use some leds for some boat lighting. So far I've had luck converting engine instruments and nav station lights to blue LEDs for dimmed lighting while underway at night. The effect is very nice and easier on your eyes at night. My old engine panel lights were consuming about 5-6 amps which is a considerable draw especially since they get turned on even in daylight. New bulb for each instrument now has 3 leds and a resistor in series, and uses about 25mA. I have 6 instruments so I have 150mA. Nav light uses a 24LED cluster, 8x25mA. We end up leaving it on all the time.
Meanwhile I ordered some white leds from china(ebay) to test on a bread board and see how they hold up before replacing more essential cabin and external lighting. I guess I will start with halogen reading lights cause they are directional.
Some issues are voltage and current ratings, and how to make a constant current supply in the range of 11-15V without overdriving the LED. I did fry some LEDs tinkering, but thats why I am testing them first.
what got me started.. http://www.fieldlines.com/story/2007/1/28/215243/977
Petar

Petar, welcome here. That looks pretty impressive. Good thinking - thanks for sharing this

I hope to see more of you here!

I know in solar they use LED because it draws less amps so the batteries last longer. Also like the thru hull LED the bulbs last 1,000 's of hours
I don't want to change any transom bulbs.

Capt. -dre'

Current problems with LED.

1) Cost
2) Heat disappation
3) Power supply
4) Life (when many LEDs are in an array of close proximity caused by #2)

Since even the white LEDs can only be powered by ~3.5V DC they become somewhat impracticle to power from household voltage.

If you string them in a series and one burns out the whole entire series goes down.

If you string them in parallel you will have one heck of a current draw when you have many LEDs and that can force the use of very large copper conductors when many amperes are drawn.

They use about half the power of a flourescent bulb for the same lighting.

I've installed 'em in customers' boats and the biggest problem seems to be in using them for ambient light. For spotlighting applications like nav and galley/reading lights they're great. They do seem to cause 'denser' shadows, which is uncomfortable for reading (at least for me). Maybe the light doesn't reflect off surfaces as well somehow...

1w LED = 4 or 5 w incandescent.

LEDs need to be fed by constant current, so with a 12v battery I wouldn't put more than 2ea. 3.5v leds in series. If you want 25 mA through them you need to series them with a 200 ohm 1/4w resistor.

I am not sure where you guys get your LED's, but I have a totally different experience.

As far as not powering them from household current, there are gobs of 110v/AC LED lights. For peanuts I bought a rope light to help guide a disabled person with poor eyesight down a hall. Uses little current and is not hot. Has been on 24/7 for a year and a half now.

On my boat I have several 12v bulbs with LED arrays inside that replaced tugnsten and halogen bulbs in reading lamps.

For area lighting I have three lamps that take full sized screw base bulbs (12v), shades have wires that clamp onto the bulbs just like household lamps. At 12v the tungsten bulbs use either 15 or 25 watts. Couple years ago I replaced them with 12v CFL's that used about a third of the current, although it was difficult to attach the shades. But at the boat show this month I bought "warm light" LED arrays inside a screw base bulb, that uses a fraction of the current of the CFL's (and the shades attach properly ).

Recently, at Lowe's I bought an LED array desk lamp. It has an array about 5" diameter and is powered at 12v/DC from 110v/AC through a little transformer. Great reading and map light! Cost $25, and I wired it directly into my 12v boat system.

My anchor light was replaced by an all around white LED array. And the tricolor has 3 separate sectors of white, green, red arrays.

There is not a large current draw for all those LED lamps in my boat. In fact it is a mere fraction of what the tungsten & halogen lamps drew, and much less than the CFL's drew. I can turn everything on and the needle on the panel's meter barely budges a smidge.

Trekka wrote:

Has been on 24/7 for a year and a half now.

LED lifetime = 100,000 hrs.

@100,000hrs.

or 11.4 years (for anyone too lazy to calculate).