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  • Newbie with Venting questions!

    Hi,

    I am in the process of installing my vent for my batteries. I have 2 banks of 4 12vdc batteries (US Battery 185HCXC) Each
    battery will be connected in series(4) with No. 2 awg copper and the 2 banks will terminate at the end of the box at 2
    400 amp rated vacuum switches so that I can isolate each bank(positive side). At the switch I will have a short 8 inch 2 awg
    wire that will tie the 2 banks together and the 4/0 copper cabling routed to E-panel about 4 ft in length. My box is wooden
    made out of 3/4" plywood and has 1 inch house siding foam on the inside for temperature changes. I also used rubber shower
    lining to protect the bottom of box and sides up to 18" above grade. The Box is 72"L X 24"H X 22"W. At the far end I have cut
    in a hole for 2" PVC pipe which rises up about a foot and using a 2" LB exists the wall to outside atmosphere At the end of the
    2" PVC I have a plumbing PVC 90 that turns down to prevent rain from entering! I purchased a 48 volt fan that moves about
    58 cubic ft of air/ minute. The fan will be mounted inside the box at the far end from the vent about 8 inches from bottom of
    box. it will be recessed in the foam insulation and I will probably hold it in place with duct tape for now. A 3" hole will be cut
    through box (plywood) for fan to pull air into box. I am not sure what is best way to wire it in - don't want a 24/7 run, but
    would prefer it to come on when bank is being charged or discharged! Not sure where to tie it in - have (3) Midnite Classic
    150s and (2) XW6048. My setup will be Grid-tie with battery backup. Most of the time I will just float the batteries and sell
    back when panels are charging. But for power outages I kill house main and grid sell and switch to Off grid for periods
    of time!

    Any suggestions are appreciated - especially on batteries! Goal is to eventually install larger battery bank that won't
    need venting. All solar equipment is in shop with other sensitive electronics present also (ham radio)

    Thanks,

    Bill
    1kwGrape,6kwSharp,3CL150
    XW6048-440 ah @ 48vdc

  • #2
    The battery box should have a slope in the lid so that H2 will rise to the high point, and then find your exit vent.

    If you pressurize it with a fan, I don't know how well that will work. There are commercial power vent kits for battery banks with a small brushless DC fan in a PVC pipe. (Zephyr )

    Be aware of the voltage requirement for your battery switches, few switches meet the voltage needs for 48V banks (about 65V when running an EQ cycle.) I'd suggest looking at Midnight Solar, and use their DC rated breakers as a switch, you will need a box to mount the switches in 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

    Comment


    • #3
      Originally posted by Mike90250 View Post
      The battery box should have a slope in the lid so that H2 will rise to the high point, and then find your exit vent.

      If you pressurize it with a fan, I don't know how well that will work. There are commercial power vent kits for battery banks with a small brushless DC fan in a PVC pipe. (Zephyr )

      Be aware of the voltage requirement for your battery switches, few switches meet the voltage needs for 48V banks (about 65V when running an EQ cycle.) I'd suggest looking at Midnight Solar, and use their DC rated breakers as a switch, you will need a box to mount the switches in too.
      Mike,

      Thanks for the quick reply, yes my box lid is sloping and drops down in the front with a 3" back area that has my pvc conduit
      going to outside air. As for the switch here is the link - I thought it would be stout enough to handle the load.

      http://www.gigavac.com/catalog/pp/ma...-switches.html

      Please take a look and let me know! I am thinking I might need a resistor on the fan for the equalization
      cycle to cut down the voltage. I will have to calculate that. I guess since the Classic 150s will be doing the
      battery charging I will need to look closer at them for a relay output!

      Oh also I saw that you quoted a average panel time based on location and time of the year, where did
      you get that information?

      Thanks for your help,

      Bill in TN
      1kwGrape,6kwSharp,3CL150
      XW6048-440 ah @ 48vdc

      Comment


      • #4
        Wow, those gigavac switches are nice. What's their cost ?

        Oh also I saw that you quoted a average panel time based on location and time of the year, where did you get that information?
        I said that ? I don't think so.

        Fans, look through some catalogs, some brushless DC fans have a wide input voltage range. I know there are 15v fans. A simple resistor will not be a great solution, as it may leave the fan stalled at lower voltages. Different fans recover differently from stalls, some shut down till power off, some constantly try to restart till they burn out/up. Most small ones will be able to be driven directly from the classic output, cross check the specs to be sure what it can drive.
        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
          Hydrogen is lighter than air - that is what you are trying to vent.
          [SIGPIC][/SIGPIC]

          Comment


          • #6
            Originally posted by Mike90250 View Post
            Wow, those gigavac switches are nice. What's their cost ?

            I said that ? I don't think so.

            Fans, look through some catalogs, some brushless DC fans have a wide input voltage range. I know there are 15v fans. A simple resistor will not be a great solution, as it may leave the fan stalled at lower voltages. Different fans recover differently from stalls, some shut down till power off, some constantly try to restart till they burn out/up. Most small ones will be able to be driven directly from the classic output, cross check the specs to be sure what it can drive.
            Mike,

            The switches were 43 dollars each - ordered 6 (3 for a friend) of them dirrectly from gigavac! The fan - I ordered (3) are all
            48 vdc but will be ok to 56vdc (see my point). I will look specs later when I am at home and can get my hands on them.
            As for the misquote I am sorry - I am looking for data showing estimated hours of sunlight based on locations. Its been
            mainly overcast this week. Just looking for info!

            Thanks,

            Bill in TN
            1kwGrape,6kwSharp,3CL150
            XW6048-440 ah @ 48vdc

            Comment


            • #7
              Bill - for close to you - PV Watts estimate for a 1 kW DC system.

              RESULTS


              3.46 90 9
              4.18 98 10
              5.17 129 13
              5.91 138 14
              6.18 145 15
              6.50 145 15
              6.55 150 16
              6.50 149 15
              5.15 117 12
              5.11 123 13
              3.65 88 9
              3.04 79 8
              5.12 1,451 $ 149
              Find A Local Installer Download Results: Monthly | Hourly
              * Caution: Photovoltaic system performance predictions calculated by PVWatts® include many inherent assumptions and uncertainties and do not reflect variations between PV technologies nor site-specific characteristics except as represented by PVWatts® inputs. For example, PV modules with better performance are not differentiated within PVWatts® from lesser performing modules. Similarly, the “Energy Value” column simply multiplies the utility-average electricity price by production. Complex utility rates and financing can significantly impact the energy value. See Help for additional guidance.
              Requested Location atoka, tn
              Weather Data Source (TMY2) MEMPHIS, TN
              28 mi
              Latitude 35.05° N
              Longitude 89.98° W
              DC System Size 1 kW
              Module Type Standard
              Array Type Fixed (open rack)
              Array Tilt 20°
              Array Azimuth 180°
              System Losses 14%
              Inverter Efficiency 96%
              DC to AC Size Ratio 1.1
              Average Cost of Electricity Purchased
              from Utility
              0.10 $/kWh
              Initial Cost 3.30 $/Wdc
              Cost of Electricity Generated by System 0.19 $/kWh
              These values can be compared to get an idea of the cost-effectiveness of this system. However, system costs, system financing options (including 3rd party ownership) and complex utility rates can significantly change the relative value of the PV system.
              [SIGPIC][/SIGPIC]

              Comment


              • #8
                Russ,

                Thanks thats the info I was looking for! Where did you get it?

                Thanks

                Bill TN
                1kwGrape,6kwSharp,3CL150
                XW6048-440 ah @ 48vdc

                Comment


                • #9
                  Originally posted by BMAD View Post
                  Russ,

                  Thanks thats the info I was looking for! Where did you get it?

                  Thanks

                  Bill TN
                  If I may: PVWatt.nrel.gov

                  Comment

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