powering multiple devices from single power supply

Discussion in 'The Projects Forum' started by dmt21, Jun 27, 2015.

  1. dmt21

    Thread Starter New Member

    Jun 27, 2015
    1
    0
    I would like to power multiple tiny computers (similar to raspberry pi) from a single big power supply rather than plug lots of the little power supplies that come with the computers into the wall.

    The power supply that comes with the device is here:
    http://www.hardkernel.com/main/products/prdt_info.php?g_code=G137454915964
    and says DC 5v 4a output.

    The actual computer I am using is here:
    http://www.hardkernel.com/main/products/prdt_info.php?g_code=G141351880955&tab_idx=1
    (Odroid XU3-Lite)

    I understand that I can buy a "big" power supply that I can plug into the wall that will power a number of these computers, but I don't understand how to
    1) pick one of them out
    2) figure out how many of the computers can be run off a single one of the big power supplies from item 1
    3) figure out how many of the big power supplies from item 1 can be plugged into a circuit without blowing a fuse. I understand that depends on the circuit's info, such as it's a 15 amp circuit or a 30 amp circuit, etc, but I don't understand how to do the calculations.

    Any help would be greatly appreciated. I'm totally new to this, so you can assume I'm totally clueless to start. Thanks in advance.
     
  2. #12

    Expert

    Nov 30, 2010
    16,338
    6,824
    All your modules use 5 volts DC. That is the voltage you need.
    All your modules use 4 amps. You need 4 amps for each module.
    Ten modules will theoretically need 40 amps. The truth is, all of them will probably never run at full capacity at the same time and need 4 real amps continuously, each.
    Still, this is a math lesson.
    Buy "a number of" modules. Multiply "a number" by 4 and that's the amps your power supply should provide.
    Watts is amps times volts. I figure 1670 watts out of a 120 volt, 20 amp wall receptical, after Electrical Code rules and 87% efficiency factor in the power supply. So, you can only run 83 modules on one wall outlet and you can only do that if your power supply produces 332 amps. Of course, 332 amps needs cables the size of a car battery, so you will be soldering 83 little power cords on to a really big copper wire.

    If you want better answers, give more information.
     
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