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How do i wire LEDS to a 12v supply Answered


I've got some LED lights that used to work of 6v a battery, 60 LEDs per light, I want to convert them to use 120 LEDs to run of a 12v system, i've got 1,5ohms and 2,9ohm resistors that came with the lights, how do i wire them to work? Might want to put 180 LEDs per light if it works, i've already burned 120 LEDs

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fjchorn (author)2011-08-07

all Leds are in parallel, i've put 2* 2,9ohm and a 1,5ohm resistor in series,the lights work but the resistors get very hot, ive got 180 leds on now

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fjchorn (author)fjchorn2011-08-07

Like I said all LEDs are in parellel,what if i group them in bunches of 60 each

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steveastrouk (author)fjchorn2011-08-08

Its a bad idea to put them in parallel, especially in a warm climate. You will; find that they burn out much quicker than you expect, and that they burn out at an accelerating rate.

As I said in my previous reply, and now emphasise, running off a solar 12V source, and burning half of the energy off in a resistor is a real waste. Arrange your source as I suggested in your other question AND SEE WHAT HAPPENS.

Steve

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fjchorn (author)steveastrouk2011-08-08

Here's the thing, the company I work for gave me a box of LED lights some Chinese brand, to come up wit a prototype for making solar street lamps, each lamp has 60 leds wired in parallel in strips of 10, if successful I will have to make 800 of them using 180 leds in each lamp, I don't want to chance to much to save on time for manufacturing, I want to run them of 12v but my first attempt blew up 120 leds, after the suggestions for putting more resistors i succeeded in making 180 leds light up of the 12v but the resistors started burning, smoking, hence the idea of making the thing run of 6v as was intended in the lamps original setup
I'm stuck again, don't know much about electronics and also have no access to electronic shops
I dissected a old computer screen today, so that's what i have regarding spares for the prototype

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steveastrouk (author)fjchorn2011-08-08

Put two lots of your LEDs in series, across the 12V supply. Job done.

Steve

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fjchorn (author)steveastrouk2011-08-08

Using the same resistors?I'll give it a go tomorrow

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fjchorn (author)steveastrouk2011-08-09

Sweet your plan works,so how would it affect my system if i put another 60 LEDs in serie?

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steveastrouk (author)fjchorn2011-08-09

You'll have to have 240 leds in your cluster, not 180, you need 120 across the supply, and you need two parallel chains, of 120 in each chain to get the numbers you need.

Steve

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fjchorn (author)2011-08-08

In Tanzania, if you don't know much it means you know something

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steveastrouk (author)2011-08-07

Sorry, never, ever in parallel.

Steve

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steveastrouk (author)2011-08-07

Paralleling LEDs is a bad idea. I'd put a resistor, and three in series, for 20 times to get a good result.

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steveastrouk (author)2011-08-07

The best way is to know the forward volt drop off the leds. White ? Guess at 3 V

Steve

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fjchorn (author)steveastrouk2011-08-07

Yes white, do i put the resistors in serie or parrelel

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fjchorn (author)steveastrouk2011-08-07

Most websites suggests that it is around 3 v
If i use double the amount of resistors used in the 6v system, wire them in parrelel, could that work?

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