power supply disconnected but another supply plugged in

Discussion in 'The Projects Forum' started by camochase, Sep 27, 2014.

  1. camochase

    Thread Starter New Member

    Nov 17, 2013
    6
    0
    I have a battery ruining a circuit. I want to have it so that I can charge the battery with a small battery charging board I bought, but I need to know how to run the same circuit from the usb (which is available on board) while disconnecting the battery to charge until the charger is disconnected. Battery is 3.7v and usb is of course 5v I need help designing a circuit for this an solution with an ic to make it simple would be nice but simple components wouldn't hurt either
     
  2. b1u3sf4n09

    Member

    May 23, 2014
    115
    14
    Do you have a schematic or part number for the charging board? What kind of battery is this?

    I have attached a doc which can help you get started. Hopefully it helps give you an idea of what kind of circuit you want or need. There is no shortage of options when it comes to battery charging.
     
  3. wmodavis

    Well-Known Member

    Oct 23, 2010
    737
    150
    "I have a battery ruining a circuit."

    You should never allow a battery to "ruin" a circuit.
     
  4. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,812
    834
    I think I posted elsewhere the need for a groan button...
     
  5. wmodavis

    Well-Known Member

    Oct 23, 2010
    737
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    I'd vote for a groin button.
     
  6. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,397
    497
    There should be a quote by someone famouse: "This problem statement is problematic."

    But I got to give points to OP for making it short and not wasting our time with the wall of text.
     
  7. tom_s

    Member

    Jun 27, 2014
    285
    333
    yes, and you were taken off the chrissy card list ;)
     
  8. camochase

    Thread Starter New Member

    Nov 17, 2013
    6
    0
    I don't have any formal schematic or anything it's just a battery charger i got off Amazon. I can send a link or take a picture but the leads coming off are battery +- and usb+-. And the battery is an old phone battery for now but the type is li-ion 1400mah and 3.7v but thanks for the help
     
  9. camochase

    Thread Starter New Member

    Nov 17, 2013
    6
    0
    From what I found the board it's tp4056
     
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