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Any electrical/electronics engineers here?

Discussion in 'General Discussion' started by engstrom0304, 12 Apr 2017.

  1. engstrom0304

    Wise Guy

    Joined: 5 Apr 2008

    Posts: 1,528

    Hi all,

    I am a mechanical engineer attempting electronics so please be nice :p

    I have a lithium ion battery pack (about 12V) for an electronics circuit and I have a separate circuit, independently powered by a 9v battery that has the sole purpose of protecting the main battery from over discharge. The idea is that when the battery falls below 3v per cell (9V) the secondary circuit will tell a mosfet to disconnect the battery.

    In order for this to work the grounds of both circuits need to be connected. The question is - do I need to use a diode to protect current from the main circuit passing through my secondary circuit?
  2. Tealc


    Joined: 13 Jul 2009

    Posts: 7,026

    Location: Llanelli

    You'd expect a battery protection circuit not to put any load on the host battery. Is it a proper circuit or something cobbled together on breadboard? Schematic?
  3. arctine


    Joined: 7 Oct 2009

    Posts: 3,951

    Why not just put the semiconductor in series with the main circuit? If it drops below 3v then the circuit is open?