Charging batteries connected in series

Discussion in 'General Electronics Chat' started by kudapete, Mar 23, 2015.

  1. kudapete

    Thread Starter New Member

    Mar 23, 2015
    I am connecting 3 12v batteries in series to produce 36 v for powering a 36v LED Module. Can I charge the 3 batteries with a 12 v charger connected to the + & - of the first battery ?
  2. nycokello

    Active Member

    Aug 10, 2009
    the solution is to use 12v by 3 charger. but if you cant get such a charger ,you may only be left with another option of charging one at long as you dont violate laws of nature.....
  3. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008

    Did you notice how, if you were to do this, there would be no charging current flowing through the other two batteries?
  4. kudapete

    Thread Starter New Member

    Mar 23, 2015
    That's what I was thinking too, I guess the only way would be to have a dedicated charging switch that changes the serial configuration to a parallel when connected to the charger Thanks for your response.
  5. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    Parallel charging is tricky.
    All depends on the battery capacity and type of batteries
  6. ScottWang


    Aug 23, 2012
    1. What is the LED Module?
    2. What kind of the battery(datasheet)?
    3. How much current of the battery?
    4. You may using a 12 V charger to charging three in parallel batteries, but this way must be disassembly the batteries, some 12V batteries can be charge by a voltage about 13.7V, so that's why we need to know more about the battery.

    5. Using a 36V battery charger, but at least the charging voltage can be using a 12.7V voltage for each one, so the charging voltage should be 12.7V*3=38.1V, some batteries maybe could be charging for 13.7V*3=41.1V.
  7. #12


    Nov 30, 2010
    R!f@@ just said, " can't just flop a switch and connect a bunch of batteries together". They aren't necessarily matched in charge quantity, and it gets worse as the batteries age. You should account for this by using about an ohm in series with each battery so they aren't very successful at trying to equalize each other when they are suddenly in parallel. A few fuses will protect you if one of the batteries becomes internally shorted and the others try to equalize its voltage.

    Trying to charge them all in series will eventually end with the weakest battery causing the others to be overcharged.
    The best you can do is separate them for service and be vigilant as they become less like their new condition.