Source switching

Discussion in 'Embedded Systems and Microcontrollers' started by Harryz, Nov 19, 2014.

  1. Harryz

    Thread Starter New Member

    Nov 19, 2014
    3
    0
    Good day.
    I have a project which involves source switching (I don't know what to call). What I want to happen are:
    I have a AC supply and a battery supply. When not plugged in, of course, the battery is the supply and when plugged in, the AC is the supply and at the same time charging the battery. How can I do this? Please help me. I really need this. I am not very fond on electronics. Thanks for the help.
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,503
    380
    Hi,
    Is the mains AC input via a battery charger,?
    You could 'float charge' the battery from the charger, so when the AC supply is present the charger supplies current to the load and it maintains the battery level.
    When the AC is OFF, the battery would automatically supply the current to the load.

    Could you post more details, ie: battery voltage AHr capacity and the load.etc

    E
     
  3. Harryz

    Thread Starter New Member

    Nov 19, 2014
    3
    0
    Thanks for your reply.
    I don't know that 'float charge'. That's a tricky one. Hmm.. Is it possible that when AC is present, AC is the main supply while charging the battery. Then when plugged out, the supply will return to battery. How about when the battery doesn't have enough load? Urghh. Now I found this project more difficult.
     
  4. ScottWang

    Moderator

    Aug 23, 2012
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    767
  5. Harryz

    Thread Starter New Member

    Nov 19, 2014
    3
    0
    How can I do that Mr. Scott?
     
  6. sirch2

    Well-Known Member

    Jan 21, 2013
    1,008
    351
    That only helps if the DC plug is pulled at the device, if the mains plug is pulled from the wall socket then it would not switch to the battery.

    A diode between the AC adaptor and the battery may be the simplest option as long as the voltage after the diode is suitable for trickle charging the batteries. A more complex circuit may be needed depending on battery type, etc.
    Code (Text):
    1.  
    2.      Mains Adaptor           Diode
    3. ~~~~~~~~AC/DC--------------- --1>|-- --------------------- Device
    4.                                                      =
    5.                                                      =  Battery
    6.                                                      =
    7. ------------------------------------------------------------------------------   GND
    8.  
     
  7. ScottWang

    Moderator

    Aug 23, 2012
    4,855
    767
    There are two kinds of plug and jack that you can use, when you google then you will see them.
    The diode you can use 1n4001 or less Vf as Schottky diode, the voltage of AC power source need little more than battery.

    Source switching_Harryz_ScottWang.gif
     
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