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  • less than ideal battery bank worth the effort?

    I have been wanting to do a solar system for several years and am now in a position to do it. I will do a whole house system, grid tied, with battery backup. I had been contemplating a Nissan leaf battery for back up. But just came across some AGM batteries manuf 2016 Power Safe SBS 190f that were taken out of service last year, 20- 12 v 190ah with a battery rack, all cableing and breakers for ea 48v string, all at basically no cost.
    This may be more than I need so I thought I could rotate the strings in service.
    Anyway, in reading here the past few days I am seeing that paralel strings are not recommended, but these cost next to nothing, so would it still be worth the effort?
    I also may have the opportunity for more when these are no longer working.
    I've been working on sizing the system and it will be 11-14kw. My kwh/day usage for four months out of the year is 75-80 and my lowest will get down to 50.
    I'm in central fl which shows 5.4 hrs/ day of sun with roof facing south.

    Thank you

    batteries.jpeg

    Attached Files
    Last edited by Castiron; 05-13-2020, 05:40 PM.

  • #2
    If those AGM's have not been getting charged monthly, I'm concerned that they may be damaged (sulfated) from sitting idle for a year. 2-3 months is OK for AGM, 30 days OK for flooded.

    What's it worth to you - cheap batteries today to tide you over for 6 months when they start to fail in the fall and you have to replace before winter ?

    With your battery backup, will you have a generator too ?
    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

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    • #3
      I forgot to mention what the batteries are, Power Safe SBS190F. (edited op with this info)
      The batteries rack and cable are basically no cost, so was hoping to get a few years out of them, but 6 months would'nt be worth the effort.
      When they are new they have a 2yr shelf life and over 10yr life in float service.
      No generator.
      Last edited by Castiron; 05-13-2020, 05:32 PM.

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      • #4
        Originally posted by Castiron View Post
        I forgot to mention what the batteries are, Power Safe SBS190F. (edited op with this info)
        The batteries rack and cable are basically no cost, so was hoping to get a few years out of them, but 6 months would'nt be worth the effort.
        When they are new they have a 2yr shelf life and over 10yr life in float service.
        No generator.
        Well you might get more than 6 months out of them but if they are 4 year old and haven't been kept on float there is no telling how they will perform under load.

        I would invest in some type of generator for both the batteries and as an emergency power supply should the batteries fail and it is cloudy.

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        • #5
          Besides the used batteries I am a little concerned that you plan a 11 - 14kw system. Is that all for the batteries or is it going to be grid tied with a hybrid inverter?

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          • #6
            Originally posted by SunEagle View Post

            Well you might get more than 6 months out of them but if they are 4 year old and haven't been kept on float there is no telling how they will perform under load.

            I would invest in some type of generator for both the batteries and as an emergency power supply should the batteries fail and it is cloudy.
            I will be grid tied so the only time I would be concerned about the batteries failing would be if the grid was down from a storm. I'm not concerned about having a backup for the backup, I'll just suck it up if that happens.

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            • #7
              Originally posted by SunEagle View Post
              Besides the used batteries I am a little concerned that you plan a 11 - 14kw system. Is that all for the batteries or is it going to be grid tied with a hybrid inverter?
              I have only lightly researched so far and have come up with 11-14k. My main goal is to be able to eliminate the power bill, potentially selling some back, and the batteries for night and when grid is down, which isn't frequent.

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              • #8
                I am retired and have a hybrid inverter already. My Nissan Leaf batteries are showing their age so I would go for it. The downside is your time but that translates into experience. The upside is you get free power. Sounds like a low risk decision to me.
                At the end of the cycle you have a nice battery rack with breakers and interconnects and some experience so when Lithium gets down to $100 per kWhr you will know how much battery capacity your will need in the longer term.
                9 kW solar, 42kWh LFP storage. EV owner since 2012

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