Short circuit protection for unprotected lithium cell pack

Discussion in 'General Electronics Chat' started by doby, May 1, 2016.

  1. doby

    Thread Starter Active Member

    Aug 17, 2011
    43
    0
    I intend on having a 2 lithium cells in a pack separate from the main protection circuitry. I'm concerned that if the wires that connect between the pack and main circuitry were to be damaged it could potentially cause a short across either cell.

    I originally thought I could just use a schottky diode in series with a each cell to protect them from such scenario, but wouldn't that give a false voltage reading for the charge circuit? The diode I intended to use has a 0.5V drop at 1A. I realise the charge current drops as it nears full capacity as would the diodes voltage drop, but in any case wouldn't it actually charge the cell over it's 4.2V maximum?

    What would be a different solution?

    Edit: Been doing a bit of digging and found this, should work nicely. The load will be pulling about 1.2A so I guess a 2A fuse should be adequate to protect against a short assuming a 18650 cell can generate no less than 2A at 2.7V

    QCbyG.png
     
    Last edited: May 1, 2016
  2. wayneh

    Expert

    Sep 9, 2010
    12,140
    3,054
    What does D1 contribute?
     
  3. doby

    Thread Starter Active Member

    Aug 17, 2011
    43
    0
    Reverse polarity protection for the rest of the circuitry.
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,140
    3,054
    D'Oh! (slaps forehead). I'm pretty sure the fuse would blow, too, but the diode does a better job of what you say.
     
Loading...