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I may have screwed up and set my charge settings too low: Tell me it will be OK

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  • I may have screwed up and set my charge settings too low: Tell me it will be OK

    I am super anal about my batteries. I have a 48v 325ah flooded battery bank (Trojan L16RE-As). These batteries are entering their fifth year of service. They have never been below 77% SOC and generally never go below 82% SOC in the winter and 90% SOC in the summer. Being a vacation place they are generally floating at 100% and when we are there they get charged to 100% every day. Equipment is Conext XW5548 with MPPT60 charge controller.

    On this last trip I had HughesNet internet installed and put in security cameras and a WIFI thermostat for our gas stove. So I made the decision to leave the inverter on so I could power the router, cameras and stove thermostat. We left two days ago and we have charged to 100% both days (I put one of the cameras facing my Bogart battery monitor which is how I know I'm at 100%).

    The problem is the batteries are drawing down to 90% SOC overnight. I though they would only draw to 95% SOC or less since there are no significant loads on the batteries. I think it's the cold weather causing this with reduced capacity (temp in the garage where bank is located is at 46 degrees but might go as low as 37 degrees or colder if we get a prolonged cold snap). The short days aren't helping either.

    I think I made a mistake by setting my Absorb voltage to 56.4v and float voltage to 52.8v. I set them to the low end of Trojan specs to reduce water loss. I'm regretting this decision but don't have the ability to make changes remotely.

    Now I'm worried about the batteries getting stuck in a partial state of charge for a prolonged amount of time. I won't be up there for another 62 days.

    What are the collective thoughts from the experts here about how long it takes a partial SOC to permanently damage batteries? In 62 days they will get an equalization charge using the generator.

    I have also decided to buy the new Conext Gateway which will allow me to make changes remotely.

    Our place is 1,200 miles away so an unplanned trip is quite the undertaking especially this time of year.

    So please talk me off the ledge.
    Last edited by hammick; 01-05-2020, 07:09 PM.

  • #2
    Are you able to recharge the batteries to 100% 3 times a week ?
    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


    • #3
      Originally posted by Mike90250 View Post
      Are you able to recharge the batteries to 100% 3 times a week ?
      I would think so but won't know for sure until I get the first day of clouds and don't reach 100%. I'm worried about getting down to 70% SOC or less and not having enough sun to catch up. I'm kicking myself for not getting remote configuration working. I tried but the Combox only allows monitoring remotely unless you get port forwarding set up. Hughesnet does not allow Static IPs.

      Each day is 1 minute longer so I believe if I make it to February I will be good to go. A big snow storm could be problematic though. Might have to hire somebody to rake the snow off my panels.

      Leaving the inverter on might not be the best idea and is probably the reason my neighbor goes through a set of batteries every few years.

      I'm contemplating putting together a cheap 12v system to power the router, camera hub and thermostat. I have two 12v panels mounted on the South exterior wall for running battery tenders. I could put those in parallel for a 12v system and add a couple panels if needed. Snow would not be an issue then.

      Is 3x per week SOC your guideline for battery health?

      Thanks.
      Last edited by hammick; 01-05-2020, 09:42 PM.

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      • #4
        somewhere between 24 - 72 hours, is when the sulfite crystals on the plates begin to irreversibly harden. Once hardened, that much chemical is taken out of the usable system and your specific gravity drops and may not be recoverable with an EQ cycle. so if you can get a full charge 2 or 3x a week, you dodge the bullet. Sulfation may decrease with cold temps, so that may help you too. But more than a couple days below 80% and you risk sulfation
        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


        • #5
          Originally posted by Mike90250 View Post
          But more than a couple days below 80% and you risk sulfation
          Mike are they less likely to suffer sulfation if over 80% SOC? I've been going on the belief that anything under 100% for a prolonged length of time would permanently lose capacity. So if you are only able to charge to 95% SOC for a couple of months over the winter you would permanently lose 5% of battery capacity. Maybe I'm in a better position than I thought.

          Comment


          • #6
            I think 95% of full, would be safe from sulfation, especially with cold temps. Who cares what I think, what do the batteries think ? I guess you will find out come spring.
            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


            • #7
              Originally posted by Mike90250 View Post
              I think 95% of full, would be safe from sulfation, especially with cold temps. Who cares what I think, what do the batteries think ? I guess you will find out come spring.
              Thanks for the helpful info Mike.

              What would be very helpful is if Schneider allowed scheduling or a timer for the inverter. A big now storm hits and I know that my panels are covered with snow. It would be great to tell the inverter to shut down for a specific period of time and then turn back on. Or even better would be dusk to dawn shutdown scheduling. As it stands now even if I buy the pricey Conext Gateway once I shut off the inverter remotely my internet is gone and I can't restart it remotely.

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