12v SLA Battery Cutoff Circuit

Discussion in 'Power Electronics' started by seanfox, Oct 17, 2016.

  1. seanfox

    Thread Starter New Member

    Mar 21, 2016
    My apologies if there is another thread here that answers this however I need your help. I am trying to come up with a very basic circuit for a bank of 12vdc SLA batteries that will do a couple of task mentioned below.


    1. Prevent deep cycling a battery - Automatically cuts off the battery from the reset of the circuit from being used if it reaches below X voltage. The trick here is that the batteries are in a series/parallel circuit. So I am thinking the only way to do this is to cut both batteries that are in series with each other if one (or both) drop below the set voltage.

    2. Overcharging Protection - A circuit that automatically cuts the charge voltage (15v) from each 12v SLA battery once the battery has completely charged. Basically this would allow each battery to be charged independently which is the ONLY way you can ensure a complete charge and ensure it's not overcharged. The charger supply would be 15VDC.

    This link is to an older thread on the subject but it seems incomplete.

    This link is along the lines of item 2 above....I think it would work but with the introduction of item 1, I am not sure how to approach. Obviously the removal of the cap and rectifier would be done since it's not needed.

    Thanks for any advise in advance!
  2. wayneh


    Sep 9, 2010
    There are a lot of 12V SLA battery charging/tending integrated circuits out there. TI has several, for instance. I'd suggest putting one on each battery. Power them all from the same supply.

    Oops, using the same supply may not be possible if you can't isolate the batteries. Hmmm...
  3. ronv

    AAC Fanatic!

    Nov 12, 2008
    How big are the batteries? In other words, what is the most current that must be interrupted?
    For the overvoltage.... Is your concern that your charger doesn't turn off? Or is your plan just to put 15 volts on the battery.
  4. seanfox

    Thread Starter New Member

    Mar 21, 2016
    Thanks for the reply we have decided to go a different direction. I would delete this thread but I can't figure out how to. Thanks
  5. tcmtech

    Distinguished Member

    Nov 4, 2013
    Half your fuses are unnecessary.

    That's just one of the smaller prices in life you will have to pay for putting ambition before planning. :rolleyes: