LEDS for everyone!

Discussion in 'General Discussions and Advice' started by Goby, 30 Aug 2012.

  1. Goby

    Goby

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    Hi all DIY LED fanatics.

    I know some of you want to go led so badly but don't know were to start. I want to share some of my own experience and knowledge of LED's so that more people can enjoy the benefits of LED lightning.

    hope that i can explain this as simple as possible for you to understand so that you can start on those energy saving LED units right away! :thumbup:

    Before starting just a friendly reminder that this DIY involves the use of electricity. Please be very careful and don't proceed if you are uncertain about anything. I won't take any responsibility when you get choaked :tt2: Now that that is outta the way lets move on.

    were to begin? i think i will start with 2 questions normally asked when it comes to LEDS.

    1. How many LED do i need for my tank
    2. How many LEDS can i run on a driver, and what driver to use with my leds.

    For an estimate of how many leds you will need to to lit up your aquarium please match your aquarium size to the closest match on my table below.

    This table is based on a led unit size of 300mm (l) x 150mm (b), with 24x3w leds, hanging 300mm+ from the water surface with +- 70 deg optics.

    Remember the following. "Smaller" optics eg 45 deg, will give less spread but more focused light and higher PAR values. So if you decide on smaller optics you may need more units to cover your entire aquarium surface. This is also the case when running the LED unit < +-200 mm from the water surface. When choosing "bigger" optics the opposite applies.

    To my research, each LED unit is fit for Softies, LPS and SPS.

    For example. You will need 3 units or 72x 3W LEDS if you have a cube aquarium size of 900mm x 900mm.

    [​IMG]

    Now that you can work out more or less how many LEDS you will need, lets look at how to calculate the amount of LED's we can connect to a specific driver. When you know this its easy to choose your driver.

    First you would need to know the following

    1. The Forward voltage range of the LED.
    2. The Max current of the LED.
    3. The Output Voltage range of the Driver.
    4. The Max Current of the Driver. (Some drivers have a current range that can be adjusted via a pod to your LED requirements)

    Check the relevant PDF data sheets for the LED and Drivers. You will find all the info there. Most online shops will give those data in their short description.

    In this example we will use the MeanWell ELN-60-48P driver and the Cree XP-E 3W LED.

    Specs of the LED
    : Forward voltage: 3.2V - 3.9V
    : Max current: 1000mA

    Specs of the driver
    : Output Voltage: 24V - 48V DC
    : Output Current: 0-1300mA

    With this specific driver the current is adjustable via a pot on the driver PC board.
    You will have to adjust it according to the max current your LED (in this case 1000ma) can handle before you connect and power any leds.

    The published forward voltage range for LEDS may be slightly off and i recommend you add 1 LED on the min voltage range to make it more safe for the LEDS and DRIVERS.

    Let's do the Math

    For the min amount of 3W Cree XP-E LEDS on the ELN-60-48P driver, you will take the drivers min output voltage range (in this case 24) and simply divide it by the minimum

    forward voltage of the LED.(In this case 3.2V)

    So 24/3.2 = 7.5 or 8 LEDS min connected in series. Added 1 extra LED for the min voltage as explaned above and throw away the decimal.

    For the max amount of 3W Cree XP-E LEDS on the ELN-60-48P driver, you will take the drivers max outout voltage range (in this case 48) and simply divide it by the max forward

    voltage of the LED. (In this case 3.9V)

    So 48/3.9 = 12.30 or 12 LEDs max connected in series. Throw away the decimal.

    Remember you only have to add 1 extra LED to the minimum voltage range to make it more safe for your led and drivers.

    Lets do another example. This time we will use the MeanWell LPC-35-700 driver and the 3W Bridgelux 4500K LED

    Specs of the LED
    : Forward voltage: 3.7V
    : Max current: 700mA

    Specs of the driver
    : Output Voltage: 9V - 48V DC
    : Output Current: 700mA

    With this specific driver the current output is fixed @ 700ma. Therefore it cannot be adjusted via a pot and it can only drive a LED with a max current of 700ma.
    You can however, connect a LED with a max current of lets say 1000ma to this driver. The led will only run at 700ma, meaning less light output but prolonged life.

    In this case we don't have a voltage range of the LED so we will just use the max forward voltage given.

    For the min amount of 3W bridgelux 4500k LEDS on the MeanWell LPC-35-700 driver.

    9/3.7 = 2.43 or 3 LEDS min connected in series ( Add 1 extra LED for the min voltage as explaned above and throw away the decimal.

    For the max amount of 3W bridgelux 4500k LED on the MeanWell LPC-35-700 driver.

    48/3.7 = 12.9 or 12 LEDS max connected in series. Throw away the decimal.

    All of the above is based on connecting LEDS in series.

    [​IMG]

    Now i will show you examples on how to connect led stings in parallel. The advantage of LEDS in parallel, you can have about twice as much led on one driver, When connecting leds in parallel the current output of the driver will be devided by the number of parallel strings. Let me explain.


    In this example we will use the MeanWell LPC-60-1400 driver and the 3W Bridgelux 4500K LED.

    Specs of the LED
    : Forward voltage: 3.7V
    : Max current: 700mA

    Specs of the driver
    : Output Voltage: 9 - 42V DC
    : Output Current: 1400ma

    You will notice that the output current of the driver (1400ma fixed) is way more than what the 3W Bridgelux 4500K LED can handle (700ma)

    When connecting 2 strings of 3W Bridgelux 4500K LED's in parallel the current will be devided by 2, giving a total current output of 700ma across the leds. (1400ma / 2)
    When connecting 3 strings of 3W Bridgelux 4500K LED's in parallel the current will be devided by 3, giving a total current outout of 466ma across the leds. (1400ma / 3)

    and so forth.........

    Calculation as follows.


    For the min amount of 3W bridgelux 4500k LEDS on the MeanWell LPC-60-1400 in parallel.

    9/3.7 = 2.43 or 3 LEDS min connected in series ( Add 1 extra LED for the min voltage as explained above and throw away the decimal.

    For the max amount of bridgelux 4500k LED on the MeanWell LPC-35-700 driver.

    42/3.7 = 11.35 or 11 LEDS max connected in series. Throw away the decimal.

    Take the maximun amount of LEDS (11) and connect them in a series string. This is your first string. Do another string of 11 LEDS in a series string. now we have 2 string of 11 LEDS in series. When we connect these 2 strings in parallel we can run a total of 22 LEDS @700ma of this one driver. This is because we are essentially splitting the amps.

    You can even run 3 strings of 11 LEDS in parallel.Then you'll be running 33 LEDS @ 466ma. The light will be less intense (because it runs at a lower current) but its life prolonged.

    Always use a fuse rated at the max current the led can handle between the driver and led strings when connecting strings in parallel. Otherwise you'll risk overdriving the LEDS when 1 or more LEDS fail.

    [​IMG]

    I hope all of this makes sense. If there is any wrong info please correct me. I have tried to do it as accurate as possible. I will try and add some additional info to make it more complete.

    Enjoy :thumbup:
     
    Last edited: 31 Aug 2012
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  3. Arries

    Arries

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    Great info man....:thumbup:
     
  4. Goby

    Goby Thread Starter

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    Ummmmm.......Vanderbijlpark is so glad that you have left. :tt2:
     
  5. Ayoob

    Ayoob

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    Thanks for sharing, definitely my next step
     
  6. carlosdeandrade

    carlosdeandrade

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    @Goby, you need to bring your family for a braai here, so that I want to chat about the unit I bought from you, I know you heard from @CW that I want to change it so that I can add a controller to get sunrise and sunset. Love what you did, and my tank looks great beacuse of it!:peroni:
     
    Last edited by a moderator: 26 Nov 2015
  7. victor du plessis

    victor du plessis

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    This is good to know info thanks
     
  8. CW

    CW

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    Jip, i saw a test unit Goby made.
    Very very nice.
    Post some pics goby.

    a Small unit like this could work brilliant for a sump light.

    pics pics pics. hehe
     
  9. butcherman

    butcherman Moderator MASA Contributor

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    Great write up!

    I would like to see the same table based on the following

    90 degree optics @ 300mm above the water
    70 degree optics @ 600mm or greater above the water
    unlensed led's (normally 120 degree veiwing angle) @ 100mm above the water

    as you said these factors can have a huge impact on the footprint you are getting.
     
  10. Hammerhead

    Hammerhead

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    Tagging, so i can locate this thread when im ready to go LED. Can Mods not sticky this
     
  11. Francois

    Francois

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    Nice info Goby,some info on the led optics.All optics will reduce overall LED light output to some degree.For maximum LED efficiency and lifespan situations, optics are not recommended.

    -For tanks up to 30 inches deep, no optics required.
    -For tanks deeper than 31 inches, 90° will be ideal
    -For tanks deeper than 41 inches, 60° will be ideal
    -For tanks deeper than 51 inches, 30° will be ideal
    -For tanks with enclosed hoods, optics are not required, because LED light is very reflective, meaning it will reflect on the inside of your tank glass down to the sandbed, with a negligible amount actually escaping*outside*of the aquarium. *Remember that the Law of Reflection states that the angle of reflection equals the angle of refraction.

    -For tanks with no hoods, where the LEDs will be mounted more than 12" above the water, consider using at least 60° optics and for distances greater than 20" inches above the water, use 30°
     
  12. nepellew

    nepellew

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    Tagging along
     
  13. Gazzer

    Gazzer

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    Tagging
     
  14. Clownfish9906

    Clownfish9906

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    tagging
     
  15. Singularity

    Singularity Hmmm amper!

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    [​IMG]
     
  16. Clownfish9906

    Clownfish9906

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    thanks @Singularity

    Guys - stupid question...would I still be able to dim my unit even though I have then leds running in parallel???
     
    Last edited by a moderator: 26 Nov 2015
  17. butcherman

    butcherman Moderator MASA Contributor

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    you mean running 2 series in parallel?
    Short answer yes.

    However it affects the max amp you run the led's at and you might need to consider putting in a quick blow fuse incase a string of led's die and you dont burn out the rest.
     
  18. mitchel

    mitchel

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    thanks for the info
     
  19. Clownfish9906

    Clownfish9906

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    thx @butcherman

    Yep the quick blow fuse is a must...reason for running parallel is that i dont have sufficient drivers and will rewire the leds as soon as I can obtain the correct drivers.

    I am using Bridgelux leds which uses less juice - or so i think...
     
    Last edited by a moderator: 26 Nov 2015
  20. butcherman

    butcherman Moderator MASA Contributor

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    bridgelux are only rated for 700ma the eln-60-48 series run a max of 1.3A are perfect for running 2 in series as you can run the bridgelux and almost 650ma which is not critical.
     
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