Author Topic: light  (Read 2517 times)

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zingaro

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light
« on: November 01, 2004, 11:58:48 AM »
I would like info on a 12v incadecent altertnative such as an led for use in an rv.

Im trying to conserve the life of the battery. Is an alternative such as led cost effective and efficient to warrant use? Thanks
« Last Edit: November 01, 2004, 11:58:48 AM by (unknown) »

sh123469

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Re: light
« Reply #1 on: November 01, 2004, 12:41:46 PM »
From what I have read, LED lighting isn't much more efficient than incandescent for the same light output.  They also do tend to be pretty directional, necessitating use of diffusers.
A CF 12v lamp would give much more light for the same amount of power consumed.  You can get them from the Dans that run this board.

Steve
« Last Edit: November 01, 2004, 12:41:46 PM by sh123469 »

Joel

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Re: light
« Reply #2 on: November 01, 2004, 08:03:32 PM »
For general lighting, sh123469 is correct.  Your best bet would probably be 12 vdc compact florescent.  Although LEDs have their advantages - long life, temperature tollerant, hazmat suitable, low heat - they are best suited for directional lighting like spot lights or specialty automotive signal lights.
« Last Edit: November 01, 2004, 08:03:32 PM by Joel »

nothing to lose

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Re: light
« Reply #3 on: November 02, 2004, 05:29:44 AM »
I thought I posted this before, but don't see it, maybe it was a different post I was replying too or again I lost one! I think it might be Inverter fans come to think of it.


 For small lighting needs at a low cost you might want to try Cold Cathode lights like for computer cases. They come in all kinds of colors including plain white. Though I never tried the whites, my 12" red puts out alot of light, and the UV ones are pretty cool too. I've had some of the various colors.


Nice things about those are they are already 12v ready, cheap, practically no heat (lower temps than flouresents I think) and not fragil, also light wieght and I think low power usage (though I never acually checked it). Kinda hard to break one without actually trying to unless you pull a wire loose!


 I looked just now and the extra tubes were around $3 each, the kits with inverter and one tube plus wiring and switch was around $5, one inverter will power 2 tubes, so for a 2 light set your looking at about $8. I buy all this type stuff from Bestbyte.net and have been happy with everything I have bought and the service. Flat rate $5 shipping for normall stuff, large items like cases or monitors might be more, but all I ever buy there are fans, lights and other small custom type items.


http://www.bestbyte.net/Product.cfm?ProductID=866&CategoryID=28&Keyword=


I am not affilated with them in anyway, just a happy customer!

That should take you to the white kits. All my color kits came with a boxed inverter and looks different than the one in the picture shown, the title does say boxed inverter though and 2 light capable which is what I do have and like.


Rather these are better than a 12v floresent not sure, probably alot less expensive and I do like them much better than any LEDS I have played with as far as actuall lighting. I like Leds for some things and have a 100 or more laying around not yet used :)


For flashlights I take recharable halogens, the big fat ones with UPS type batteries inside and mod them to LEDs. With the halogen bulb the battery lasts maybe 20-30 minutes, with LED I never had one go dead yet, but I do get alot less light too.

 I use the LED ones for general walking around in the dark, use the halogen ones for spotlighting to see if that's a skunk or opossum scrathing in the distance!!


For the cost of my Leds and the amount of light 12 make I would think the cathode kits will make more light for less money than LED, as far as power used for an equal amount of light that I am not sure about. I never strung that many leds together yet!!

« Last Edit: November 02, 2004, 05:29:44 AM by nothing to lose »

ghurd

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Re: light
« Reply #4 on: November 02, 2004, 09:11:40 AM »
For lighting a whole room, the CFLs always win. I like the cold cathodes too, but don't see much difference in the 2, have not used too many.


For a tiny amount of light, the LEDs will win. If you just need to see to get down the hall to the bathroom, 0.010 amps will do it. A little reading light on the bed, 0.040 amps will do it. That is with good LEDs, not the ones from the store in the mall.  The batteries go dead from sitting faster than running a small LED light all night, every night.


Big light- CFL.

Little light- LEDs


G-

« Last Edit: November 02, 2004, 09:11:40 AM by ghurd »
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nothing to lose

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Re: light
« Reply #5 on: November 02, 2004, 09:28:24 AM »
"A little reading light on the bed, 0.040 amps will do it. That is with good LEDs, not the ones from the store in the mall.  The batteries go dead from sitting faster than running a small LED light all night, every night."


Yep,

That reminds me, I wired 3 or 4 Leds and connected them to a old 7ahr 12v battery from either a flashlight, rechargable aircompresser, or a dead UPS for my wife as a reading light. She used it everynight for along time, 30 minutes to an hour at least, and I never recharged it. Thats been months since I made it! It was still working the last time I saw her use it too. She changed work shifts now, so she does'nt use it since it's daylight when she's reading.


Personaly I never read in bed myself, I tried it once and the computer nearly killed me when it fell over, and the monitor was too heavy and made it hard to breath with it sitting on my chest anyway :)


.

« Last Edit: November 02, 2004, 09:28:24 AM by nothing to lose »

ghurd

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Re: light
« Reply #6 on: November 02, 2004, 10:13:25 AM »
Did it with a laptop. Fell asleep with my finger on "Enter". Sent my sister the same email 7600 times.
« Last Edit: November 02, 2004, 10:13:25 AM by ghurd »
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ghurd

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Re: light
« Reply #7 on: November 02, 2004, 10:15:34 AM »
By the way. You can't really 'buy' a good LED light quite yet. At least not many places.


It would be far better to make one.  Its not to hard.

« Last Edit: November 02, 2004, 10:15:34 AM by ghurd »
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bob golding

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Re: light
« Reply #8 on: November 02, 2004, 12:08:38 PM »
hi all i am doing some experiments with lighting at the moment. strung 18  10000 mCD white leds together. it gives a good reading light and draws about 350 mA at 12 volts. got 2 240 volt 21 watt CFLs running though an inverter, they draw 33 watts each, just ordered 20 cold cathode tubes to play with. they are supposed to draw about 5 watts each. will report back when i get them set up. certainly pleased with the leds. ordered another 100 from ebay. direct from hong kong. they usually take about 10 days to arrive.


bob golding

« Last Edit: November 02, 2004, 12:08:38 PM by bob golding »
if i cant fix it i can fix it so it cant be fixed.

ghurd

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Re: light
« Reply #9 on: November 02, 2004, 04:28:39 PM »
Hi Bob,


You are smoking the LEDs, or they are not wired quite right! How blue are they? That's a sign.


55ma is going to cook them. Fast. Couple hundred hours at most I figure. And your light to watts is WAY down.


Or you are using 'hockey pucks', and your light to power is again way, way down.


Cut 'em back to 20 and the life will go up exponentially as will the output per watt. 15 is better.


G-

« Last Edit: November 02, 2004, 04:28:39 PM by ghurd »
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bob golding

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Re: light
« Reply #10 on: November 03, 2004, 04:32:26 PM »
hi ghurd,

i reckon 350 mA divided by 18 comes out at 19.5mA per led. cant see were you get 55 mA from? they dont seem to be running hot. the resistors  get warm but thats because they are 1/8 watt ones i just had kicking about. think i wil get some of those 12 volt compacts from the dans if my cold cathodes dont do the job. played with my 6 peltiers today. they are giving out about 15 watts just sitting on the stove with a heatsink sitting on top. very pleased with them,looking forward to rigging them up properly with fans and clamping them tightly. fans draw 2 watts each so  should  still have about 10 or 12 watts to play with hopefully.


cheers

bob

« Last Edit: November 03, 2004, 04:32:26 PM by bob golding »
if i cant fix it i can fix it so it cant be fixed.

ghurd

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Re: light
« Reply #11 on: November 04, 2004, 10:57:16 AM »
For 12 volts, wire 3 LEDs in series.  For 18 LEDs, that's 6 strings of 3 LEDs.

Just 1 resistor per string. 20ma per string.


  1. strings at 20ma is 120ma.  Same ma to each LED, so same brightness.
  2. ma goes down to 120ma.  Saves 2/3 of the power.


Wasted power in your resistors is about 4 times what it would be wired this way, so the resistors won't get warm either.


Glad to hear about the peltiers.  Thats on the list when the money gets better. I would love to see some numbers for that!  I have a couple ideas to do away with the fan. To compicated to explain, but easy to do.


For the fan, How about a 5v 150ma laptop fan? Moves some air, low corrent, run it direct from 1 additional electricialy seperate peltier? Maybe even 2 from a single peltier?


G-

« Last Edit: November 04, 2004, 10:57:16 AM by ghurd »
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tawa

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Re: light
« Reply #12 on: November 19, 2004, 01:20:56 PM »
Whoa, wait a minute. Are you saying that peltiers give off electricity if you apply heat? I thought only special prototype chips did that? (Aren't peltier plates the ones that have one cold and one hot side if you apply electricity?)
« Last Edit: November 19, 2004, 01:20:56 PM by tawa »