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Circuit to shut off inverter at low battery voltage set point = 50%

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  • #16
    Google " adjustable low voltage disconnect " and look under shopping, dozens of choices to look through
    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



    • #17
      Using voltage to determine if the battery is charged or not is going to be very disappointing. After a few hundred false trips, spoiled food, hot beer, and dead fish in aquarium you will wish you had never used one and will toss it out in the trash with all the other garbage the LVD made for you.
      MSEE, PE


      • #18
        I have, just wondering if anyone did that for battery protection, i have a small backup system running and things that are direct 12v need a shut off. also trying to grandpa proof it incase he doesnt heed warnings of just running more 12v stuff if the inverter taps out.


        • #19
          Originally posted by DSII View Post
          Charge controlers have an adjustable high voltage set point, so the batteries are not over charged. If you place a relay circuit that disconnects the batteries from the inverter so the voltage does not fall below the 12.06 50% level it would reduce damage to the batteries. The problem is that the circuit will need to not enguage the inverter until the voltage is some what higher like 12.30 volts.
          The right way to do this is with a BMS like the FlexNet DC (from Outback.) They provide a relay output. Use that output to disable your inverter. Most better inverters have an enable/disable input. Then set the FlexNet to open the relay at 50% battery capacity and close it at 80% battery capacity (or choose your own levels.)

          If you prefer, drive a larger relay with the small relay output to cut off DC power to all your loads.

          A not so great way to do this is use a charge controller or inverter with an auxiliary output. The Outback inverters and the Midnite charge controllers provide this output. Use it to enable/disable the inverter based on voltage (probably under 12 volts.)