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Thread: 12v PS into a 5v LED - what will happen?

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    Newbie Extraordinaire... scottmcl's Avatar
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    Default 12v PS into a 5v LED - what will happen?

    I'm pretty sure I know the answer. But I'm asking anyway... If I run a 12v power supply into a 5v LED, what will happen to the LED? Just shorten the life? Make the magic smoke come out of it? (Wanted to ask before I "tried it"...)

    In very related news, how do I found out if a commercial LED is 5v or 12v?

    I'm converting a retail light string that currently runs on a 3AA battery pack and I want to put it on a real power supply, though still battery operated. Just a bigger (marine) battery. We've already modified the string of lights so that there is about 10' of cord between each light. I'm noticing a little more than 1v of loss over the 100' of the string of lights when I use my multimeter to test the voltage at each end of the string of lights. So it would be awesome to use a 12v supply on these lights as we want to string 3 of them together. I'm planning to use the standard waterproof connections for pixels between the strings. The distance means at least 3-5v of loss over the 300' of power, likely more. Which is why I'm thinking of using a 12v power supply instead of a 5v power supply.

    Thanks for the help!!!
    - Scott M.
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    Havin fun ! kidcole's Avatar
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    Default Re: 12v PS into a 5v LED - what will happen?

    Quote Originally Posted by scottmcl View Post
    I'm pretty sure I know the answer. But I'm asking anyway... If I run a 12v power supply into a 5v LED, what will happen to the LED? Just shorten the life? Make the magic smoke come out of it? (Wanted to ask before I "tried it"...)

    In very related news, how do I found out if a commercial LED is 5v or 12v?

    I'm converting a retail light string that currently runs on a 3AA battery pack and I want to put it on a real power supply, though still battery operated. Just a bigger (marine) battery. We've already modified the string of lights so that there is about 10' of cord between each light. I'm noticing a little more than 1v of loss over the 100' of the string of lights when I use my multimeter to test the voltage at each end of the string of lights. So it would be awesome to use a 12v supply on these lights as we want to string 3 of them together. I'm planning to use the standard waterproof connections for pixels between the strings. The distance means at least 3-5v of loss over the 300' of power, likely more. Which is why I'm thinking of using a 12v power supply instead of a 5v power supply.

    Thanks for the help!!!
    To help answer your question, I would first need to know if you are talking about LED bulbs from full wave rectified AC strings, or dumb LEDs, or pixel bulbs ?

    There is not that much tolerance to most LEDs tho. A typical 5V pixel LED will be at the upper limit of its tolerance at 6V. Much over that and you will fry it .. or let the smoke out (which has the same effect) ..
    Thanks,

    Denny Cole
    https://www.facebook.com/groups/Cole...ristmasLights/

    Back to Work <unretired> so I went Static in 2017. Planning xLights when I retire <again>. Maybe 2019 ?

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    Newbie Extraordinaire... scottmcl's Avatar
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    Default Re: 12v PS into a 5v LED - what will happen?

    Quote Originally Posted by kidcole View Post
    To help answer your question, I would first need to know if you are talking about LED bulbs from full wave rectified AC strings, or dumb LEDs, or pixel bulbs ?
    No clue, to be honest. They are LEDs. That's all I've got...

    Quote Originally Posted by kidcole View Post
    There is not that much tolerance to most LEDs tho. A typical 5V pixel LED will be at the upper limit of its tolerance at 6V. Much over that and you will fry it .. or let the smoke out (which has the same effect) ..
    That's what I figured. Not sure there is a good solution then. Thanks!!!
    - Scott M.
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    Super Moderator EricR's Avatar
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    Default Re: 12v PS into a 5v LED - what will happen?

    I think those have to be 5v because easy AA battery is only 1.2V. I'm no expert but I don't see how a 12V light would work well with 3.6V.

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    Havin fun ! kidcole's Avatar
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    Default Re: 12v PS into a 5v LED - what will happen?

    Quote Originally Posted by scottmcl View Post
    No clue, to be honest. They are LEDs. That's all I've got...
    Then assuming they came from AC light strings with a rectifier added, the most common LED voltage is 3.4 volts. Those would come from a string of 70, which is divided into two groups of 35. 120 volts divided by 35 bulbs is about 3.4v. So 3 batteries in series would probably work perfect for them.
    Thanks,

    Denny Cole
    https://www.facebook.com/groups/Cole...ristmasLights/

    Back to Work <unretired> so I went Static in 2017. Planning xLights when I retire <again>. Maybe 2019 ?

    Falcon - 3 F16V3 & 1 PiCap, Sandevices - 2 E681 & 4 E6804, 288 Channels Lynx Express, 108 Channels DC DMX,
    10' Pixel MegaTree, CoroFlakes w/Pixel Modules, Pixel RBLs, 2 Pixel Matrix 16x25, 10" RGB Ornaments, 7x230 Pixel Icicle Matrix,
    Classic 20' AC Megatree, TIR Destiny RGB Spots, RGB Blowmolds, Wireframes, and Inflatables with External Light Control

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    Professional Net Lurker Jack Stevens's Avatar
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    Default Re: 12v PS into a 5v LED - what will happen?

    Scott -

    You might want to try something like this - a DC to DC converter.
    LM2596S Adj DC DC Buck Regulator Power Module 3A Adjustable 5V 12V 24V | eBay

    I bought several for $1.22 each after blowing up a couple of ESPixelSticks due to overvoltage, so I could safely run them from phone chargers and/or a high-amperage 12 volt power supply I have.

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