LED lighting

[Paul Bailey]

Anyone in the group using/or experimenting with LED lighting in the HOME as yet. ,with positive results. As they say Every kilowatt counts..and I might be able to get a couple here!.:)

[Joe Blake]

Not in a big way, but it's certainly on my "list of things". However, a couple of weeks ago I did purchase a set of LED bicycle lights, front and rear (white and red). The front light has 3 white LEDs and is too bright to be looked at directly, even from a distance of about about 4-5 metres in twilight. It uses three "AAA" batteries, and is reckoned to give 8 hours of continuous light (although the capacity of the batteries was not made clear).

The lamp is probably the size of a smallish banana (although not bent) and weighs very little. It fits into a pocket and has a clip on the end. The lensing arrangement focuses the light in a narrow, bright beam, so it's not really suitable for "overall" lighting. However, I wonder whether it would be possible to construct some sort of "exponential horn" mirror which would disperse the light in an annular fashion, with the light shining vertically (either up or down).

Cost? Well, I bought the two lamps plus a bicycle computer with all the appropriate mounting hardware for $39 Australian. I already had 4xAAA batteries (rechargeable NiMH) and I have a couple of solar powered metered battery chargers, so in some senses, I've got free spotlighting.

Might be able to build some sort of stand to hold the lamp as a reading light.

I'll keep my eyes open for a set which has only got the headlight, because I think they are very useful anyway, as a torch, storm light, and so forth.

As a follow on, or tangential thought, I am almost fully equipped with compact fluorescent light sources through my house, and usually have the smallest ones which draw about 3 watts. However, these ARE obviously very dim, and sometimes I need something brighter, so I've had a thought that perhaps instead of having to get up and unscrew the dim globe and replace it with the brighter ones, perhaps it might be possible to have two sockets in the same fitting, with two different wattage globes, and two switches on the wall, one for each globe, or even a chain operated "swap" switch which would turn one on and the other off. I don't think money wise it would be worthwhile, but it's certainly a way of using less power. (With all the climate change happening "suddenly" (Hah!!) our pollies are starting to talk about people having to pay a more "realistic" (ie higher) price for power and water. So who knows? It MIGHT pay off in the long-run.)

Joe

[Rob Beckers]

This has come up before in http://www.greenpowertalk.org/showthread.php?t=412

To reiterate, the average currently available LED bulb is about as efficient in lumens/Watt as the average CFL bulb. So, your 1 Watt LED will give off about as much light as a 1 Watt CFL, ie. not very much. LEDs are much more directional though, so that 1 Watt LED may well be too bright to look at. Just don't try to light up a room with it though. The other issue with LEDs at this time is their CRI.

This is a fast moving field though. So hopefully a really useful LED bulb will come along sooner rather than later!

-Rob-

[Mark Parsons]

Hi Paul,

I recently replaced 3 - MR16 20W Halogen with these 1.2W LED units in my kitchen.
http://www.e-sonic.com/whatsnew/weekly_VaOpto_MR16.htm

Much improved over a multi-LED version I tried about a year ago. I would say these units put out about 1/2 the 20W halogen lux - to my eye anyway. The CRI is poor - quite blue. Wouldn't want to cook under them but they work great to see what is in the pantry. Saving over 18 watts per light is also great. My track light is a transformer 12VAC type so I just barely see a little flicker from them due to 1/2 wave rectification, I assume. I presume that 12VDC full wave would resolve this.

Mark

[Paul Bailey]

These MR-16 LED units are NOT dimmable ...correct??

[Rob Beckers]

Not sure if one can buy this in the shop, but LEDs are actually very easy to dim: By driving them with a current source instead of a voltage source, and simply regulating the current. Done it many times.

-Rob-

[Ted Sanford]

Hi,
I'm just passing on something that a friend showed me.
If you take two of the 36" long, 3/4" dia flourescent bulbs, wire up ends for them to a 2 lamp, T8 ballast, and put them on opposite sides of a 16'x16' room, they will light it very well. The bulbs, ends and ballast are available at Home Depot for not much.
You get more light, and more even light, for 60 watts this way than compact flourescents. I made a little deflector from some cedar I had laying around to shine lthe light up and down, instead of into your eyes.
Ted

[Paul Bailey]

Anyone in the group have a link or a reasonably accurate converter ??? More so for LED's and the amount of lumens thier producing for various wattages. In other words...I'm getting interested in these Led's again:)

[Rob Beckers]

Paul, lumens/Watt for LEDs is all over the place. From less than CFL, to about twice as much for the more experimental LEDs (most better commercial ones are just about the same as CFL in lumens/Watt these days). The manufacturer's docs give the numbers.

-RoB-

[Joe Blake]

Not quite sure if this converter is of any use.

http://www.mastlight.com/tool.html

If you're into caving, this may be useful.

http://caves.org.uk/led/foot1.pdf

http://caves.org.uk/led/foot3.pdf


Just yesterday I bought a handful of white automotive LED "globes" as used in turn indicators. I'm going to play round and see if I make some sort of "multi-spot" light from PVC pipe, that will run directly off 12 volts. The globes were just under $10 (Aus) each and the appropriate globe holder (pre-wired) were $4+ each. So for under $15 plus scraps of PVC water pipe I may have a viable light.

Will keep you informed.

Joe

[Paul Bailey]

Thanks Joe and Rob for the followup. I also did some more internet digging and I'm presently stalled on this since led's still don't represent good value ( $$ spent vs light output) Especially now that regular compact flouresants are now Cheap and are of good value with lots of bulb sizes available ( I now have about 55 compacts in service for over 15 years and lost only a few) I'm also testing 4 Led bulbs but really there just way too much $$$ money for the available light output ...Paul:)

[Rob Beckers]

Paul, what you write pretty much sums up my take on LEDs at this time.They are currently no more efficient than CFLs, and for most of them their spectral output is horrendous. Both of these things are changing though and LEDs may very well have a bright future (pun intended). It just hasn't arrived yet...

-RoB-

[Joe Blake]

Finally finished my basic light fitting using LED car globes.

http://i82.photobucket.com/albums/j245/saxeharp/lights.jpg

Haven't been able to give it a full try out, but a couple of points of interest. The globe holder base is wrapped in foam rubber and gaffer tape, which gives each individual fitting a small amount of flexibility. Plus of course the T-junctions can also give some directionality. Using these 4 lights can give a "broad spot" ie an area of very bright light with faint shadows where there's no overlap between. And being auto sockets the globes can be changed very quickly to give different colours (if you really want them).

I haven't been able to measure the wattage drawn, but based upon very sketchy research on the net I calculate that it should be drawing about 2-3 watts.

I've already given the cost of the lights etc. The T-junctions and right angled fittings were $1.50 and .90 cents each respectively, and obviously can be re-used for something else.

And of course the whole thing is presently just a "press fit" model, and can be reconfigured into different shapes.

Joe

[Joe Blake]

These piccies show the sharp definition of the lit area comparing the lighting on my hand to that on my face and the shadow pattern generated on being lit from behind. The room is rough 4-5 metres across, and I'm standing about a metre and a half from the light source.

http://i82.photobucket.com/albums/j245/saxeharp/lights02.jpg

http://i82.photobucket.com/albums/j245/saxeharp/lights03.jpg

Joe

[Mike Green]

Anyone in the group have a link or a reasonably accurate converter ??? More so for LED's and the amount of lumens thier producing for various wattages. In other words...I'm getting interested in these Led's again:)

lumens per watt is the very parameter by which we rate the lighting efficiancy of an installation. Joe posted some converters for candela to lumens. (candelas are handy when evaluating a beam, as in using halogens for hi-lighting, lumens are necessary for calculating the amount of light on a surface- Lux)
As such a watt lumen converter would not exist as an empirical converter across the board, rather the opposite is so. the lumens per watt ratio is a value specific to a specific brand and model number of light bulb.

[Larry Hollenberg]

I have one of those multi led lamps in a stairway light because it uses very little power and can be left on for some time if I wished. I tried it in a lamp with very unsatisfactory results, very blue light and not flattering to the surroundings. Worst part was it was the most expensive bulb I ever bought. So I would say till they perfect something better I wouldn't want them other than for the steps.

[Joe Blake]

Since putting together my little system shown above, I managed to make some "diffusers" would you believe by cutting a suitably sized hole in a white ping-pong ball.

http://i82.photobucket.com/albums/j245/saxeharp/P8140044.jpg

If you're wondering about the reddish tint, the LED globe on the left is actually a red 12 v automotive one, and in real life, it looks a bright red ping pong ball.

These globes have 19 LEDs, which is probably the same as the ones you are using.

I've got these light running off my old 12 volt battery pack from my electric trike, and I had them on for something 5 days continously before I realised the batteries weren't connected to the charger. The globes (ping pong balls) stayed at air temperature (15-16 degrees C) after all that time. They're not bright, but I'd certainly say they're a great emergency light.

http://i82.photobucket.com/albums/j245/saxeharp/ping.jpg


In Australia, they cost about $10 each globe.

I'm making up a bracket so I can carry one white and one red LED globe on my trike if I ride at night time.

Joe