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  • Float mode period

    Hello,

    My solar dealer/supplier tells me my batteries bank do not have to enter float mode every day. His calculations show that my SOC will oscilate between 50% and 100% for 1 week or 2 during the 3 months wet season. Is that ok?
    I have heard that batteries should enter float mode every days but does that has to be every day of the year or can I accept 1 week or 2 periods during the year without reaching 100% SOC?
    On the other side, during nearly 8 consecutive months the batteries will enter float mode every days with no less than 75% SOC.
    Thanks in advance.

  • #2
    Correction:
    His calculations show that my SOC will oscilate between 50% and 80% for 1 week or 2 periods during the 3 months wet season.

    Comment


    • #3
      Below about 80% of full, sulphate crystals start to form on the lead plates. they can be easily dissolved after 1 day. the longer they persist, the "harder" they become and the more difficult to drive back into the acid solution. Each crystal (starting as the size of a grain of salt) lowers the battery capacity. Over time, as more and more crystals persist, the battery looses capacity. If it was I, I would buy an extra panel or whatever it takes to get to 100% full at least every 3 days. A week is too long, and permanent damage would start. Or maybe you like to buy batteries, Your call.
      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


      • #4
        Good to know. Better buy a panel then. Thanks for your advice. But doesn't equalization resolve this cristal issue?

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        • #5
          No. EQ solves the issue of subtle charging differences between cells in the battery. Once the crystals have hardened for a couple of days, they appear to become permanent. There are stories of De-Suphalte boxes that claim to recover the battery, but they have not proven out after 50 years.
          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

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