how long to charge two 12 v 200ah batteries connected in series

Discussion in 'General Electronics Chat' started by t00t, Feb 13, 2015.

  1. t00t

    Thread Starter Member

    Jan 22, 2015
    i recently bought a ups with output 24v dc going to charge my old batteries which both is 12v 200ah each connected in series . the batteries are about 3 years old . i have charged it using my new ups for about 35 hours but the total voltage in the batteries are still 19.5v .
    so i was wondering how long would it actually take to charge it to 24v. or are the batteries actually spoiled ? The batteries used are lead acid batteries .
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    Disconnect the batteries, and let them sit for 24hours. Measure the open-circuit voltage of each battery with an accurate DVM, and report back...
  3. #12


    Nov 30, 2010
    It sounds like at least one of them is, "spoiled".
    Then again, the charger might be bad.
    That's why we need measurements.
  4. MikeML

    AAC Fanatic!

    Oct 2, 2009
    If the batteries sat around for three years during which they were never charged, then you might as well recycle them and buy new ones. Letting lead-acid batteries self-discharge is the worst thing you can do to them.