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Thread: How do I power 18 x 10w leds

  1. #1

    Default How do I power 18 x 10w leds

    Hello,
    First post here. Looking for some help. I am a mechanic but electronics is definitely not my strong point. Picked up 3d printing as a hobby and trying to build a sla printer. My build will require me to put out about 150 watts for whatever LEDs I end up using. I want to go with many 10 watt LEDs so I can achieve very good light displacement rather than using 3 x 50 watt LEDs. The LEDs I want to use are 10w LEDs with a forward voltage of 8-12v and a forward current of 1000ma. Due to powering other parts of the printer I have to go with a power supply that outputs 12 volts. My power supply plugs into power outlet and puts out 12v up to 20 amps.

    Very new to electronics and want to know first of all is it even possible to power about 15-17 x 10w LEDs? Do I wire them in series or parallel? Should I try and find a constant current led driver? If so do I just set the output at 12v @ 15 amps to achieve ~ 150-180 watts?

    Not asking yall to just give me the answer but point me in the right direction. Tried some LED wizards but not sure if those take into account the constant current led driver or simply use transistors to regulate the strings of LEDs.

    Thanks in advance. Any input positive or negative is appreciated.

  2. #2
    Flashaholic Hoop's Avatar
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    Default Re: How do I power 18 x 10w leds

    Hi, Fswc39. Welcome to CPF.

    If you aren't dead set on using that 12v power supply of yours you could use an adjustable constant current AC/DC led power supply like the MEAN WELL HEP-185-12A. That outputs ~12v, so all LEDs would be wired in parallel and the current split between them. The problem with a big string of parallel LEDs like that is that one or more of them might see a lot more current than the others due to forward voltage inconsistencies. It is better to wire them 4s4p, or 5s3p, etc. In the case of 4s4p you could use an HEP-185-48A.
    Last edited by Hoop; 03-04-2019 at 04:00 AM.

  3. #3

    Default Re: How do I power 18 x 10w leds

    Quote Originally Posted by Hoop View Post
    Hi, Fswc39. Welcome to CPF.

    If you aren't dead set on using that 12v power supply of yours you could use an adjustable constant current AC/DC led power supply like the MEAN WELL HEP-185-12A. That outputs ~12v, so all LEDs would be wired in parallel and the current split between them. The problem with a big string of parallel LEDs like that is that one or more of them might see a lot more current than the others due to forward voltage inconsistencies. It is better to wire them 4s4p, or 5s3p, etc. In the case of 4s4p you could use an HEP-185-48A.
    Thank you. Just the direction I needed. I am going to look at the one you recommended and see if I can make it work with the other components. I'll let u know. Thanks a bunch once again.

  4. #4

    Default Re: How do I power 18 x 10w leds

    Quote Originally Posted by Hoop View Post
    Hi, Fswc39. Welcome to CPF. If you aren't dead set on using that 12v power supply of yours you could use an adjustable constant current AC/DC led power supply like the MEAN WELL HEP-185-12A. That outputs ~12v, so all LEDs would be wired in parallel and the current split between them. The problem with a big string of parallel LEDs like that is that one or more of them might see a lot more current than the others due to forward voltage inconsistencies. It is better to wire them 4s4p, or 5s3p, etc. In the case of 4s4p you could use an HEP-185-48A.
    Ok so it looks like the hep-185-48a will definitely work. However I will still need to use the original psu that I stated bc I need it to power other parts on this build. I'm running the psu I stated to a raspberry pi equipped with a nanodlp shield if you have ever heard of it. Basically the nanodlp receives the 12 volt output from the psu and powers the 12 volt components (fan, etc.) And at the same time steps down the voltage to 5v for LCD, LCD Driver and nema17 stepper motor. The nanodlp has a 12v output for connecting LEDs to it. I would like to somehow connect the hep-185-48a to it. Do you think I could use a solid state relay and connect it to the 12v output of the nanodlp and convert the current back to AC current so i can connect the mean well driver to it? Or is that not how electricity works?

  5. #5
    Flashaholic* DIWdiver's Avatar
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    Default Re: How do I power 18 x 10w leds

    Yes, a solid state relay designed to handle line voltage AC loads should work quite well.

  6. #6
    Flashaholic Hoop's Avatar
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    Default Re: How do I power 18 x 10w leds

    Doesn't a parallel string have the advantage in a failure scenario? The remaining LEDs stay on and distribute the current. If an LED dies in a series string the whole string turns off. If one dies in a 4s4p array, the remaining 12 LEDs will take on the current from the 4 dead LEDs which is an extra 33% to each LED. Regarding my last post, I'm not so sure that LED voltage disparity would actually be an issue in a parallel array of high power LEDs.
    Last edited by Hoop; 03-04-2019 at 11:41 PM.

  7. #7

    Default Re: How do I power 18 x 10w leds

    i would recommend a dc-dc driver to specfically drive the led seperate from the input voltage for that matter you could run anything into the printer and use a dc-dc converter to put 12v into the printer system and then another to go into the leds or whatever.
    https://www.ledsupply.com/blog/wirin...its-explained/
    Last edited by lunas; 03-05-2019 at 10:50 AM.

  8. #8

    Default Re: How do I power 18 x 10w leds

    Thank you for the input from everyone. Still unsure of which route is the best but I understand current a little bit better now and should be able to figure it out from here.

  9. #9
    Flashaholic Hoop's Avatar
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    Default Re: How do I power 18 x 10w leds

    Is there enough voltage overhead from a 12v power supply to power 12v LEDs with a DC-DC driver?

  10. #10

    Default Re: How do I power 18 x 10w leds

    i had similar project, i used 10 3x leds for my 3d printer, all wired in series, i ended up using 32v 350ma power supply from old printer, and i used no driver, just connected straight to the PS. current is in safe range, voltage matches requirement for 10 leds in series, so driver isn't needed.

    in your case you have 18 12v leds that draw 1A each, and 12v PS. simplest way is connect them all parallel, which generally not a good idea, but if you use a resistor for each led, small nominal, it will be ok, you do not need any drivers that way.

  11. #11

    Default Re: How do I power 18 x 10w leds

    Ok thank you I will look into that. How small of a resistor are we talking. Isnt there a calculator somewhere that helps you figure out resistor size?

  12. #12

    Default Re: How do I power 18 x 10w leds

    Quote Originally Posted by Hoop View Post
    Is there enough voltage overhead from a 12v power supply to power 12v LEDs with a DC-DC driver?
    All the DC-DC I looked at look fairly unimpressive....

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