battery isolation ?

Discussion in 'General Electronics Chat' started by jrm, Feb 25, 2012.

  1. jrm

    Thread Starter Member

    Oct 11, 2011
    38
    2
    I need to add an Auxilliary power input jack to an existing project that is normally supplied by Li ion batteries. I would like to isolate the batteries from the circuit when external power is supplied. My initial thought is to just use a pair of n channels like this:http://www.falstad.com/circuit/#$+1...256+208+416+208+0+1+true w+864+496+864+320+0

    (I put a lamp in the simulation in place of the board regulator)

    Is there a better way? maybe a single chip solution? I'm not opposed to making a charging circuit either.
     
  2. jrm

    Thread Starter Member

    Oct 11, 2011
    38
    2
    Does anyone see anything wrong with this circuit to isolate the Lithiums when the 12v dc adapter is plugged in?

    I feel pretty confident that it will work but since the risk of failure here would include damaging an existing project, I am seeking feedback from those more experienced than myself.
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,014
    3,234
    That looks ok to me. I simulated your circuit using a 0-12V pulse for V2 and it switched between sources as you wanted.
     
  4. jrm

    Thread Starter Member

    Oct 11, 2011
    38
    2
    Thanks for taking a look Carl. I'm not confident in my spice fluency yet so I just wanted to make sure.


     
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