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  • Low voltage disconnect?

    Hi Folks,

    I have a very simple system. The charge controller won't disconnect until the battery is about dead (11.1v). I bought a 70a LVD to save my batteries, but I'm having a devil of a time getting it to work correctly. I can get it to pass enough voltage to power a dc lamp, but the inverter will not work on it.

    The only way it seems to pass voltage at all is by going straight from the battery negative terminal to the load and routing the positive through the disconnect. There are three other wires on this LVD in one harness: The SNS, IGN, and GND.

    http://www.cooperindustries.com/cont...133123070.html

    http://www.ebay.com/itm/271538603866...%3AMEBIDX%3AIT

    Any thoughts on how to wire this bad boy?

  • #2
    OK first the CC has nothing to do with a LVD. Some units have a built-in LVD cicruit, but they are every small loads like a small LED light. Other than that they are completely useless. But the charge controller never ever gets disconnected from the battery never ever ever, it always remains connected to the battery. Did I mention the CC stays connected to the battery ALWAYS. Only thing that ever goes between the controllers output and battery is a FUSE. NEVER EVER A LVD


    Now you can can add a disconnect between the battery and a load device like an inverter. They are simple devices with at least 3 wire connection.
    1. Battery Positive Post. It can have some different names like Source, Batt, or Input. It will be a heavy gauge wire and/or terminal on the LVD. It has two jobs. To power the LVD sense circuitry, and high current Relay contact.
    2. Will be the output to the inverter, and can be labeled Load or Output. This will also be a heavy gauge wire and/or terminal for the high current.
    3. Ground. A small gauge wire needed to complete the power to the control circuitry. This will be a small gauge wire. It will be called either Ground or Return. Ground is a terrible name. Should be connected directly to the battery term post because it also doubles as the voltage sense line.

    It can have other optional connections like IGN or Ignition when used in autos as a battery isolator. IT might also have a Bypass so you can push a switch and force it to close even if the battery is low.
    MSEE, PE

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    • #3
      Originally posted by Sunking View Post
      3. Ground. A small gauge wire needed to complete the power to the control circuitry. This will be a small gauge wire. It will be called either Ground or Return. Ground is a terrible name. Should be connected directly to the battery term post because it also doubles as the voltage sense line.

      It can have other optional connections like IGN or Ignition when used in autos as a battery isolator. IT might also have a Bypass so you can push a switch and force it to close even if the battery is low.
      Thanks Sunking! I have attached a photo of what I have so far. The LVD taps into the battery to CC wiring on the input side of the breaker.

      As far as the GND wire...Whenever I attached it to the negative battery output, the LVD "sings" and no voltage comes out of the positive output.

      Thomaspoa
      Attached Files

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      • #4
        lvd

        i am pretty new to solar but have had a wind charger for a couple of years, i just installed a couple of solar panels and did not want to damage my battery,i use it to stabilize my voltage so as not to damage my grid tie inverters. i bought a 12 Volt, 15 Amp Low Voltage Disconnect Battery Saver [1950-222] from batterymartcom on eBay.
        i used it to control two 12 volt relays that feed the battery power to the inverter , i used two relay because my inverter will draw more power then one could handle on a continuous basis. it is adjustable and i set it on 11.5 volts when the panels become shaded and the voltage drops it disconnects the inverter and when the voltage comes back up it reconnects. i don't see why you could not use bigger relays or more relays these are just what i had handy.

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