Rechargeable circuit 9.6v nimh 8 batteries in series

Discussion in 'The Projects Forum' started by tycbox, Mar 5, 2015.

  1. tycbox

    Thread Starter New Member

    May 9, 2014
    Hi, I'm working on a fun project to build a custom battery charger. Here's my specs below.
    it has to charge 8 x 1.2v aaa rechargeable battery nimh in series = 9.6v
    currently i'm using a 12v generic charger.
    I found this schematic (attached picture) and got it to work but someone told me that the circuit I have is just a voltage regular, it doesn't monitor the current level and this circuit can over charge the batteries? I was wondering if there's anyway to improve on this schematic and not over charge the batteries to cause a fire or something. I read somewhere that I can buy this chip LT1513CR for my purpose since I'm using 8 batteries in series, but I want to build my own circuit and play around with it. Anyway to improve my circuit to do things similar to the LT1513CR chip? Can someone please help?

    Thanks in advance,

  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    The circuit you posted is for Sealed Lead Acid Batteries; not for NiMH or NiCds. NiMh is one of hardest batteries to charge because there is not a reliable end-of-charge indication, except a possibly a temperature rise. Most commercial appliances that use NiMh embed a thermistor in the pack, and the charger shuts down when the battery begins heating.

    Read about NiMh charging algorithms here.
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
  4. tycbox

    Thread Starter New Member

    May 9, 2014