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Thread: Not Sure How To Power & Drive 48 LEDs for Aquarium Fixture

  1. #1

    Default Not Sure How To Power & Drive 48 LEDs for Aquarium Fixture

    I have 48 Lumileds PWF6-type LEDs mounted to metal pucks that I would like to make into a fixture for my new 55gal salt-water reef aquarium.



    I'd like to power the LEDs at 300-350mA each, which would make each LED voltage around 3.2V. This provides about 72 lumens / each.
    Theyre mostly neutral-white LEDs (just blue dies with green phosphor) and a few cool-white. I plan to scrape off the green phosphor on some of them to make em pure-blue for the live corals.

    Question is, which driver / power supply combo would be best to plug into a typical 120V household socket?
    I also hope to add potentiometers to dim each string of series.

    I did some searching and found a couple aquarium builds, but they all seem to use tiny 10V power adapters with higher voltage output drivers (like 24-48V DC output). Like this: http://www.nano-reef.com/forums/inde...owtopic=261164
    I'm worried that it might be too small of a power supply. That seems kind of expensive, too. So, please share if you have any ideas that are cheaper.
    Last edited by Darkhorse85; 06-29-2012 at 02:42 PM.

  2. #2

    Default Re: Not Sure How To Power & Drive 48 LEDs for Aquarium Fixture

    OH!

    lol, it just clicked. Those meanwell drivers plug in to the wall directly, no need for an additional power supply. And that small 10V is just for the potentiometers!
    http://www.rapidled.com/mean-well-el...mmable-driver/

    of course!

    This is my first time wiring LEDs. heh

  3. #3

    Default Re: Not Sure How To Power & Drive 48 LEDs for Aquarium Fixture

    So, here's what I had in mind. meanwells will be too expensive (only handle 14 LEDs each)

    The one thing im not really sure about is splitting the current post-700mA buckpuck. Do you think I'll be able to get 350mA for each strand of 6 LEDs?
    8x350mA bucks is double the cost of 4x700mA, and I'm doing this project on a budget (hence the salvaged P/S)

    Last edited by Darkhorse85; 06-29-2012 at 06:14 PM.

  4. #4
    Thread Killer Illum's Avatar
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    Shrug Re: Not Sure How To Power & Drive 48 LEDs for Aquarium Fixture

    There other driver alternatives to Luxdrive series you know, for example, theres this: dimensions: 0.89" x 0.39" x0.33"
    http://www.mouser.com/ProductDetail/...%2f8eho5M00%3d
    I've been using its bigger brother, the LDD-700 for quite some time without any issues

    And no, on paper parallel strings without ballast resistors should theoretically consume the same amount of current, In reality due to differences in the forward voltage of the LEDs the string with the lower forward current will consume more current. This leads to two separate events: Uneven intensity and the risk of a cascade failure if your LEDs are only rated for 350ma. As the LED heats up, its forward voltage decreases. This in term increases forward current. The more current it consumes, the hotter its going to get.... then eventually This is the reason why it is advisable to 1: operate LEDs using constant current and 2: for fixed lighting, avoid paralleling strings.

  5. #5

    Default Re: Not Sure How To Power & Drive 48 LEDs for Aquarium Fixture

    Thanks for the advice! That looks like a great option.

    Glad I waited on ordering stuffs.

  6. #6

    Default Re: Not Sure How To Power & Drive 48 LEDs for Aquarium Fixture

    (1) Using DC/DC bucks of any sort is 'oldschool' for reeflights. I'm a regular on the reefing forums, and there are only a few specific circumstances you'd have an advantage going DC/DC, and this is not one of them.

    (2) It won't work anyways. You have 6 LEDs at 3.2 volts which is a total of 19.2 volts, assuming the forward voltage is correct (not sure given I can't find the tech doc for this emitter). You can't run a 19.2 volt draw off a Buck using a 19.5 volt input because you need a couple volts of overhead on the input side.

    (3) Parallel runs are common with big reef lights. Riskier than single series runs, but no big deal if you are carefull. Not familiar with these LEDs, but if they can handle a max 700mA then running two strings in parallel at 350mA poses no risk because even if one string conks out it won't hurt anything.

    (4) Only way to save money going DC/DC is using fixed DC drivers, and you are silly to build a reef light without being able to dim one color, preferably the royal blues. You are better off using a 120volt Mean Well 48D, or slightly more expensive Inventronics. Both have dimming capability although the Mean Well requires some additional parts to do so.

    (5) Not surprised your aren't getting a response in Reef (Creep) Central. Not the nicest forum on the internet if you aren't doing it 'their' way. NanoReef is typically friendlier towards ad-hoc designs.

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