24vdc gate, 12vdc intercom 160m remote site

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  • broljo
    Junior Member
    • Mar 2015
    • 5
    #1

    24vdc gate, 12vdc intercom 160m remote site

    I have registered here to try and get some advice with a solar powered sliding gate system. the gate is approx 160 meters from the house and there is no mains electric so hence the solar system.

    The gate system is 24dcv and the battery pack is 20ah charged by a 24v 30w panel.Originally it had a 15w panel but i have gone up to the 30w in order to have a greater charge rate in case we have a cloudier spell of weather.
    I am also wanting to fit a wireless video/intercom system that I am assured will work over the distance as there is line of sight from the gateway to the house with no obstructions. However this is a 12v system and draws 60ma at standby and 300ma when in use.
    My questions( as a newby with solar) are;
    1. Can I use the 15w 24v surplus panel (says it has an open voltage of 42v) to charge a separate 12v battery for the intercom system?

    2. Would it be better to add the 15w panel to the 30w in parallel and power the 12v intercom from the present 24v battery ( with a transformer or some such)?

    3. What charge controller,fuses,etc etc would I need if i use a separate battery for the intercom and what size 12v battery would I need?

    Any kind advice would be most welcome
    thank you
    Last edited by Mike90250; 03-28-2015, 06:52 PM. Reason: fix thread topic
    Tags: None
    • Mike90250
      Moderator
      • May 2009
      • 16020
      #2
      You first have to find out what the power draw of the 12v radio at the gate site is, because that value will determine how much power you need to harvest & store.

      With things needing 2 different voltages, I think it's best to have 2 separate systems to begin with.
      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

        • Bala
          Solar Fanatic
          • Dec 2010
          • 716
          #3
          Why not use a 24v to 12v reducer, i use one in my system.

            Comment

            • bcroe
              Solar Fanatic
              • Jan 2012
              • 5198
              #4
              Originally posted by Bala
              Why not use a 24v to 12v reducer, I use one in my system.
              I would favor the 24 to 12 voltage reducer PROVIDING it meets a couple requirements.
              First it should be a high efficiency type such as a small buck converter (seen on Eb+y
              for a couple bucks) and sized small enough not to waste much power. AND it may
              require some shielding/filtering to prevent any switching noise from interfering with
              the radio linK.

              Do figure just what is needed and build a conservative system. The radio system needs
              some 20 watt hours a day; I'd use a battery good for a week and panels able to recharge
              in one sunny day. With enough panel watts, you will be able to keep even, even on
              largely cloudy days.

              Radio range problems can come up. I have multiplied the range of similar radios many
              times by using a high gain antenna designed for the frequency, placed at the building
              end. Bruce Roe
              Attached Files

                Comment

                • broljo
                  Junior Member
                  • Mar 2015
                  • 5
                  #5
                  Thank you so much for your replies.

                  To Mike;
                  The radio intercom takes 60ma on standby and 300ma when operating but that would only be in short spells when somebody arrives at the gate.
                  To Bruce:
                  The system comes with a dual high gain antenna to reach the distance involved so I am hoping that will work OK.
                  If I powered it off the 24v battery with a reducer to 12v should I run both panels together to charge it?

                  The specs on the system state that the maximum current of the 24v battery is 10W and that would also supply the gate motor.

                  If i use a seperate 12v battery solely for the intercom what size do you suggest and with what charge controller. Most of them seem to have a 40v max voltage and this 15w panel gives out 42 open circuit.

                    Comment

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