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  • Help please

    I recently purchased an off grid home, all was well till the shorter days , I find myself running the backup generator 2 hours a night to keep my battery bank ( 8 x 100ah gell) up above 12.4 v.
    The only thing running on the batteries is water pump and our lights.
    We pee outside to minimize flushing and turn on one 8 watt led for a few hours at night.
    I have 4 x 100 watt shell energy panels (sm 100 12p) with a 2.8 kw magnum inv/charger. I find it hard to understand why 8 batteries can't keep a charge with only one light on and everything else is unplugged.
    We use very little power( no appliances, toasted, hairdryer, absolutely nothing)
    Do the batteries need replacing?
    Can I replace with 2/350 amp hour vs 8x 100 am/h?

    Please help

    Jason

  • #2
    If all connections are good and the proper gauge cable, the batteries may be junk. Having a 12V set up is rather hard to do. It requires far too much cable expense to get good current flow.
    To answer the question of batteries, any time you can use fewer batteries to get the AH you need is better. Your first step is to work your needs, then from that determine what the system should be. It is very possible your system was assembled by someone who just bought components without any knowledge of what or how to do it.
    6,32 KW solar, net metered, maple syrup producer.

    Comment


    • #3
      Jason Gel cells are the last thing that should ever be used. Time to replace them. Having said that 400 watt of panels can only support a 12 volt 200 AH battery. You have 12 volt 800 AH. Your panels and controller at best can only support a pair of 6 volt golf cart batteries.
      MSEE, PE

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      • #4
        Ok, so what needs to be replaced?
        Batteries, panels ...
        Will the inverter be ok? It has a manufacture date of 2010, I have a 50 amp mppt charge controller.

        Thanks

        Comment


        • #5
          Easy, start with batteries, a pair of Trojan T-105RE.
          MSEE, PE

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          • #6
            Great I guess the solar dream is over, I've already invested more than I should have in this place.
            Generator and battery bank it will be.

            Thanks for the help.

            Comment


            • #7
              You learned something today. That something is the difference between your daily need and Demand. Solar can meet your needs over a period of time, but cannot meet your demands of energy every day. You have to have a conventional source of power to meet your demands. So if you want solar, you must also build a conventional source to replace it standing by hot and ready to go. With solar you pay twice. Once for the dream you found in that Bong, and agian when you sober up and find yourself without power with a generator or conventional power generation.

              MSEE, PE

              Comment


              • #8

                It's been a long time, but isn't smiley using this thing backwards?

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                • #9
                  Am I dreaming to think I can make this work with 4 newer panels and 3 trojan batteries?
                  With generator backup? Still keeping upgrade cost low?
                  Why can't I use this inverter?
                  Who can direct me to someone with straight forward answers instead of lessons of the day?

                  Comment


                  • #10
                    Originally posted by wannabe Hippy View Post
                    Am I dreaming to think I can make this work with 4 newer panels and 3 trojan batteries?
                    With generator backup? Still keeping upgrade cost low?
                    Why can't I use this inverter?
                    Who can direct me to someone with straight forward answers instead of lessons of the day?
                    You first asked only about replacing the batteries and when somebody told you what kind of batteries to get you decided to give up. Nowhere did anyone say that you could not get by with just replacing the batteries and the panels, but the very first thing you need to have to get the right answer is an accurate estimate (or preferably measure) of how much energy you use in 24 hours. Buy a KillAWatt power meter and start measuring.
                    SunnyBoy 3000 US, 18 BP Solar 175B panels.

                    Comment


                    • #11
                      Originally posted by wannabe Hippy View Post
                      I recently purchased an off grid home, all was well till the shorter days , I find myself running the backup generator 2 hours a night to keep my battery bank ( 8 x 100ah gell) up above 12.4 v.
                      The only thing running on the batteries is water pump and our lights.
                      We pee outside to minimize flushing and turn on one 8 watt led for a few hours at night.
                      I have 4 x 100 watt shell energy panels (sm 100 12p) with a 2.8 kw magnum inv/charger. I find it hard to understand why 8 batteries can't keep a charge with only one light on and everything else is unplugged.
                      We use very little power( no appliances, toasted, hairdryer, absolutely nothing)
                      Do the batteries need replacing?
                      Can I replace with 2/350 amp hour vs 8x 100 am/h?

                      ///

                      Am I dreaming to think I can make this work with 4 newer panels and 3 trojan batteries?
                      With generator backup? Still keeping upgrade cost low?
                      Why can't I use this inverter?
                      Who can direct me to someone with straight forward answers instead of lessons of the day? ......
                      The batteries are shot. Do you have a pressure tank in your water system ? That will help reduce the pump starts.

                      Adding more panels and their own charge controller will help.

                      But first, count up all your loads like this:

                      Light 8w x 6 hours = 48watt hours
                      pump 900w x .3 hrs = 270 wh
                      laptop 90w x 4 hours = 360

                      and so on.

                      Your inverter has to be large enough to start the pump motor, but all that "largeness" also means lots of idle power waste.
                      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


                      • #12
                        Originally posted by wannabe Hippy View Post
                        Am I dreaming to think I can make this work with 4 newer panels and 3 trojan batteries?
                        If you are referring to Trojan T-105 batteries, then you are dreaming. Better said do not understand. The T-105 batteries are 6 volts. No way to use three 6 volt unless you want a 6 or 18 volt system.

                        Originally posted by wannabe Hippy View Post
                        With generator backup? Still keeping upgrade cost low?
                        Any off-grid system requires a generator and must be included in the budget.

                        Originally posted by wannabe Hippy View Post
                        Who can direct me to someone with straight forward answers instead of lessons of the day?
                        All of your questions have been answered in the order you asked them. However that is a moot point. The question you must answer before going forward is to determine your daily watt hour usage for worse case. Once you know that along with location, then you can proceed with a design.
                        MSEE, PE

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