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  • #16
    Originally posted by miles View Post
    Total power coming in form my panels is 50A so I have them in 2 banks of 4 (in parallel), then each bank of 4 is connected to my garage (8 or 9 meters run) by 4mm wire, so therefore each run of wire will see max of 25A...
    Like I said your wire is way undersized. That means you are loosing approx 8 volts between your panels and charge controller or put another way burning up 8 volts x 25 amps = 200 watts on the wiring.

    You need to upgrade your wiring to 10 mm.



    Originally posted by miles View Post
    the project was about finding out if it was a viable way of saving money
    Impossible to save money taking anything off grid. Just in battery replacement cost alone you are looking at paying 60-cent per Kwh the rest of your life plus inflation as battery prices rise you have to replace every few years. Nothing FREE about it.
    MSEE, PE

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    • #17
      well I have worked out that if I only discharge my batteries to 80% capacity I can do this maybe 2500 times as a conservative estimate (6.8 years)? unless I am talking nonsense (please feel free to correct me anyone who is an expert on gel traction batteries), so during daylight hours I charge my batteries and run 600 watts of equipment (as long as the sun comes out)! Once sun is gone equipment runs at 300W until batteries are 20% discharged then equipment switches back to mains power...

      My batteries cost me £300 because i'm lucky enough to know someone who works with forklifts so even if they last me 3 years I would have saved enough to pay for these plus lots more.

      I have taken on board your comment ref the voltage loss on the 4mm wire and may upgrade but as we all know 10mm wire is really expensive!

      And surely 2 runs of 4mm wire is equivalent to 1 run of 8mm? or are you saying I should have 10mm for each set of 4 panels?

      I have doubled up my wiring (2 x 4mm) on my system near my controller & trip switches & uprated to 100A trip switches to see if this cures the problem.

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      • #18
        Originally posted by miles View Post
        well I have worked out that if I only discharge my batteries to 80% capacity I can do this maybe 2500 times as a conservative estimate (6.8 years)? unless I am talking nonsense (please feel free to correct me anyone who is an expert on gel traction batteries), .....
        There is nothing magic about gel traction batteries. I am pretty sure you will NOT see 2 years (700 cycles) of taking them 80% down on a daily basis (or are you saying you will only take 20% charge off the cells ??)

        BatteryServiceLife.jpg

        20% may be too shallow, as occasional deeper discharges activate virgin areas of the plates. And are you speaking of GEL batteries or AGM ? AGM can provide deep and rapid cycles, GEL is often just used in long standby applications like backup lighting.
        Last edited by Mike90250; 02-28-2014, 03:39 PM.
        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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        • #19
          Originally posted by miles View Post
          well I have worked out that if I only discharge my batteries to 80% capacity I can do this maybe 2500 times as a conservative estimate (6.8 years)? unless I am talking nonsense (please feel free to correct me anyone who is an expert on gel traction batteries),
          OK there is no such thing as Gel Traction batteries. Gel batteries are too fragile (sensitive to high currents charge and discharge rates experienced in traction batteries) and failure rates too high to be used in forklifts. 1 to 2 years max with the batteries.

          Fork lift batteries are AGM.
          MSEE, PE

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          • #20
            Originally posted by Sunking View Post
            Fork lift batteries are AGM.
            Or Flooded, as long as there is no special reason to go with Sealed.
            SunnyBoy 3000 US, 18 BP Solar 175B panels.

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