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  • Rv power; please help ?

    New to forum, I am building my own camper and need help with panel and battery size, I am mounting 4 - 120 W panels at 480 Watts and 4 - 130 ah batteries at 520 ah, I am using a 30 A charge controller, my total power output is 1315 Watts with microwave, but only up to 10 minuets at 900 Watts, 7.5 A a day, most of the time only fridge will run at 180 Watts, 1.5 A, for maybe 5 hours we will watch TV, using laptop and maybe lights at 415 Watts, 3.5 Amps, will this work ? and maybe ball park to how long to charge batteries with full sun at 6 plus hours a day. Thanks, any help is good.

  • #2
    Originally posted by Rick C View Post
    New to forum, I am building my own camper and need help with panel and battery size, I am mounting 4 - 120 W panels at 480 Watts and 4 - 130 ah batteries at 520 ah, I am using a 30 A charge controller, my total power output is 1315 Watts with microwave, but only up to 10 minuets at 900 Watts, 7.5 A a day, most of the time only fridge will run at 180 Watts, 1.5 A, for maybe 5 hours we will watch TV, using laptop and maybe lights at 415 Watts, 3.5 Amps, will this work ? and maybe ball park to how long to charge batteries with full sun at 6 plus hours a day. Thanks, any help is good.

    Start Here


    IMHO,
    480watts of PV will work for about 1200wh... in minimum 4 hour insolation.
    However, an inverter will cut into efficiency and lower to 1000wh.
    The 12v/520ah battery works well into that equation, but 4x parallel is not recommended.
    [CENTER]SunLight @ Night[/CENTER]

    Comment


    • #3
      Originally posted by Shockah View Post

      Start Here


      IMHO,
      480watts of PV will work for about 1200wh... in minimum 4 hour insolation.
      However, an inverter will cut into efficiency and lower to 1000wh.
      The 12v/520ah battery works well into that equation, but 4x parallel is not recommended.
      THANK YOU for the fast help, but I am not Shure what you mean by parallel, Pos to Pos, Neg to Neg makes 12V, Pos to Neg makes 12 X 4 = 48V, Right ?

      Comment


      • #4
        Originally posted by Rick C View Post
        THANK YOU for the fast help, but I am not Shure what you mean by parallel, Pos to Pos, Neg to Neg makes 12V, Pos to Neg makes 12 X 4 = 48V, Right ?
        Correct.
        Pos to Pos, Neg to Neg makes 12V = Parallel.
        Pos to Neg makes 12 X 4 = 48V = Series.

        Series draws current from batteries equally... better for longer life.

        What is the input voltage of your inverter?

        FYI:
        (4) 12v/130ah in series = 48v/130ah
        (4) 12v/130ah in parallel = 12v/520ah
        [CENTER]SunLight @ Night[/CENTER]

        Comment


        • #5
          Fist two huge expensive mistakes you are doing is using 12 volt battery panels and a PWM controller. It is a waste of money and energy. You can use two grid tied panels of 240 watts each at 1/2 the cost with a 40 amp MPPT controller. Total cost will be less than 4 battery panels and PWM controller. That is the money part. For the energy part It only takes a 330 watt MPPT system to equal a 480 watt PWM system. Or a 720 watt PWM system to equal a 480 watt MPPT system.

          Next mistake is using 4 12 volt batteries in parallel. If you need 520 AH @ 12 volts then use either 4 or 6 volt 520 AH batteries wired in series.

          Last point is you are going to need a generator, or a battery isolator for the vehicle alternator to do most of the charging for you.
          MSEE, PE

          Comment


          • #6
            Originally posted by Shockah View Post
            Correct.
            Pos to Pos, Neg to Neg makes 12V = Parallel.
            Pos to Neg makes 12 X 4 = 48V = Series.

            Series draws current from batteries equally... better for longer life.

            What is the input voltage of your inverter?

            FYI:
            (4) 12v/130ah in series = 48v/130ah
            (4) 12v/130ah in parallel = 12v/520ah
            Inverter is 2500 Watt Power Drive, 12V input, I guess I forgot to include that, I'm a retired truck driver and buy a lot of my stuff at truck stops.

            Comment


            • #7
              Originally posted by Sunking View Post
              Fist two huge expensive mistakes you are doing is using 12 volt battery panels and a PWM controller.
              I didn't catch it was a PWM CC...?

              Rick said 30amp, I assumed MPPT you assumed PWM... I'm not putting any money on my assumption
              [CENTER]SunLight @ Night[/CENTER]

              Comment


              • #8
                Originally posted by Rick C View Post
                Inverter is 2500 Watt Power Drive, 12V input, I guess I forgot to include that, I'm a retired truck driver and buy a lot of my stuff at truck stops.
                Bad combo.
                Start again.
                See Sunking's post above and use Off-Grid Calculator.
                [CENTER]SunLight @ Night[/CENTER]

                Comment


                • #9
                  Originally posted by Shockah View Post
                  I didn't catch it was a PWM CC...?

                  Rick said 30amp, I assumed MPPT you assumed PWM... I'm not putting any money on my assumption
                  Real simple he is using 12 volt battery panels, 4-12 volt batteries, and if he had a MPPT controller it would have to be a 40 amp unit to handle 480 watts. He is not that informed.
                  MSEE, PE

                  Comment


                  • #10
                    Originally posted by Rick C View Post
                    Inverter is 2500 Watt Power Drive, 12V input, I guess I forgot to include that, I'm a retired truck driver and buy a lot of my stuff at truck stops.
                    Ditch the inverter. You have no use for a 2500 watt inverter and only invites a fire. Use 12 volt RV equipment. If you need 120 VAC use as small of an inverter as you can.
                    MSEE, PE

                    Comment


                    • #11
                      I am building this camper on the back of my pickup truck, I already have inverter and batteries, the pocket I built for batteries is 14 X 10 X 30, I have room for four Batteries and no more, panels, I can do something else. I don't know the deference in inverters, I had this inverter in my semi truck and ran off the truck batteries, like I said, I am a truck driver and only thing I know about 12V power is what I learned from other truck drivers, and that's not much, HA HA.

                      Comment


                      • #12
                        Originally posted by Rick C View Post
                        .......I am a truck driver and only thing I know about 12V power is what I learned from other truck drivers, and that's not much, HA HA.
                        We will educate you. Stop building anything. You are going to have to make a HUGE shift from Truck with nearly unlimited power, to your camper, with a 100A alternator. Every watt you can save makes a big difference. Solar will never be aimed right, and therefor, you should only expect about 1/2 the nameplate power from the PV. Huge battery bank only means huge expense to replace it in a year when it dies.

                        Read the link about system size and the Off Grid Calculator.
                        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


                        • #13
                          Originally posted by Mike90250 View Post
                          We will educate you. Stop building anything. You are going to have to make a HUGE shift from Truck with nearly unlimited power, to your camper, with a 100A alternator. Every watt you can save makes a big difference. Solar will never be aimed right, and therefor, you should only expect about 1/2 the nameplate power from the PV. Huge battery bank only means huge expense to replace it in a year when it dies.

                          Read the link about system size and the Off Grid Calculator.
                          I don't know what link you are talking about ? if its the one earlier in this thread it won't open, using truck alternator won't work because I will sit for up to 2 weeks in one spot and can not afford the gal. per hr. my truck burns, also running 1/O wire from front of truck to back camper is 18 ft. is that not a long way? the batteries I have I just bought a year ago, they are the same as my last ones that I used for 5 years, I would run stuff until alarm would sound and then I would start gen. for half a day, but gas cost to much on retirement.

                          Comment


                          • #14
                            Originally posted by Rick C View Post
                            I don't know what link you are talking about ? if its the one earlier in this thread it won't open, ......
                            Off-Grid Calculator Link >>> http://www.solarpaneltalk.com/attach...2&d=1340038558
                            It is an excel spreadsheet compressed into a "zip" file.

                            Bottom line is you have a poor match of components.
                            It would be similar to putting your pick-up truck engine in your 18 wheeler and expecting to haul a full load cross-country.

                            Firstly, sell the 2500watt inverter to another trucker.

                            Another great link for you >>> http://www.solarpaneltalk.com/showth...-Size-Tutorial
                            [CENTER]SunLight @ Night[/CENTER]

                            Comment


                            • #15
                              I agree with much of what was said to you and being you have the batteries already then try to get a 24 volt or 48 volt inverter to better utilize them. You mention you bought them a year ago so how did you maintain them for that year? If they weren't properly cared for you may be replacing these soon too.

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