Replace 100Ah for 300Ah 24v battery

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  • Takis
    Member
    • Oct 2019
    • 64
    #1

    Replace 100Ah for 300Ah 24v battery

    Hello friends,

    I want to expand my battery bank. My mppt charge controller can achieve 40amps current. So I'm thinking of buying a 300ah c20 battery bank but I don't know how to test if my system can support it.

    My panels are exceeding the wattage limit of my charge controller. Maximum is 1040w but my panels are 1300w (2 strings of two pairs of 330w, almost 85voc and max current of 9.5 amps per pair).

    What I need is 30amps for sure an average day.
    How to test if my system can support 30 to 40 amps?
    Is it better to choose a 250ah battery bank so as to use inverter and charge batteries at the same time or to safely get those 25amps?

    My current battery bank is 100ah.
    Tags: None
    • organic farmer
      Solar Fanatic
      • Dec 2013
      • 658
      #2
      Any way that you add an additional string of batteries, will cause those new batteries to mimic the old batteries.

      If your older batteries were near the end of their life span, than suddenly these new batteries will mimic the older batteries and they will appear to be near the end of their life span.

      If you want to shift from having 100ah of battery bank to 200ah of battery bank, you are best to do so when you are replacing the old batteries. So that all of your batteries are in fact the same age.

      4400w, Midnite Classic 150 charge-controller.

        Comment

        • Mike90250
          Moderator
          • May 2009
          • 16020
          #3
          1300 W of panels, can be expected to produce 80% of nameplate, when they are warm in the sun!

          That's 43A into a 24V battery bank (you never mentioned the battery bank voltage) ( 86A at 12v, or 21A @ 48V )

          So you have the #'s now and can figure it out for your bank voltage. Ask if you want to learn how to figure it out for yourself

          Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
          || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
          || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

          solar: http://tinyurl.com/LMR-Solar
          gen: http://tinyurl.com/LMR-Lister

            Comment

            • Takis
              Member
              • Oct 2019
              • 64
              #4
              Sorry,

              The title is wrong. I want to replace my old battery bank. From 100ah to 300ah.
              My system is 24v.

                Comment

                • SunEagle
                  Super Moderator
                  • Oct 2012
                  • 15151
                  #5
                  Originally posted by Takis
                  Sorry,

                  The title is wrong. I want to replace my old battery bank. From 100ah to 300ah.
                  My system is 24v.
                  I changed the topic title. I hope that is better for you.

                    Comment

                    • Takis
                      Member
                      • Oct 2019
                      • 64
                      #6
                      Originally posted by SunEagle

                      I changed the topic title. I hope that is better for you.
                      Yes. Thank you.

                        Comment

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