LVD after charging with generator

kansaskansas Solar Expert Posts: 98 ✭✭
Just used my backup Iota 45 DLS charger for the first time.  The batteries were down to 60% and no sun on the horizon so I rolled out the generator and plugged in the charger.  In a little less then 2 hrs the batteries were back to 90%.  When I returned two days later, after a sunny day, the batteries were still at 90%.  I checked the control panel and saw that the charge controller was blinking red, indicating a low voltage disconnect (LVD).  I rebooted the system and all is fine now.  Can anyone explain why using the Iota charger would trigger the PV charge controller to LVD ?  The Iota is hardwired to the battery bank.
Two 140 watt Kyocera panels, wired in parallel; Ironridge top of pole mount; two 6 volt, 242 AH US batteries, wired in series; Morningstar ProStar 30 charge controller and SureSine 300 inverter; Trimetric 2025-A meter; IOTA DLS-45 charger, Honda EG3500X generator; Aermotor 702 water pumping windmill.

Comments

  • BB.BB. Super Moderators Posts: 26,872 admin
    Which solar charge controller?

    Sure it was LVD and nitty HVD (high voltage disconnect)?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • kansaskansas Solar Expert Posts: 98 ✭✭
    Morning Star Prostar 30. Definitely LVD, the red light was blinking. The HVD is supposed to automatically reconnect, the LVD at 12.6 volts. The Trimetric showed 90% and SG was okay so the batteries were not discharged, certainly not to the LVD level which is 11.4 volts. Charge controller is only a few years old,
    Two 140 watt Kyocera panels, wired in parallel; Ironridge top of pole mount; two 6 volt, 242 AH US batteries, wired in series; Morningstar ProStar 30 charge controller and SureSine 300 inverter; Trimetric 2025-A meter; IOTA DLS-45 charger, Honda EG3500X generator; Aermotor 702 water pumping windmill.
  • EstragonEstragon Registered Users Posts: 1,616 ✭✭✭✭
    Might be worth checking voltage at the Morningstar battery output terminals, and retorquing all connections.

    I'm wondering if maybe vibration from the genny worked something loose enough to cause enough voltage drop to trigger LVD?
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • kansaskansas Solar Expert Posts: 98 ✭✭
    I'll check the connections.  The generator was outside and not near the charge controller.  The Trimetric meter showed a normal charging curve from 60% to 90%, starting at about 13.6 volts, increasing to 15 volts at 90% when I was using the charger.  I had the IOTA set on the fast charge cycle in order to match my battery specs, including the specs for an equalizing charge.  Even if the LVD was real, it should have reset once the input voltage reached 12.6, which it surely did with full sun the following day (or second day?).  There was limited sun yesterday but the SOC reached 95%.  Wish I was out there today to see if anything has changed.  Inverter was off the entire time. 
    Two 140 watt Kyocera panels, wired in parallel; Ironridge top of pole mount; two 6 volt, 242 AH US batteries, wired in series; Morningstar ProStar 30 charge controller and SureSine 300 inverter; Trimetric 2025-A meter; IOTA DLS-45 charger, Honda EG3500X generator; Aermotor 702 water pumping windmill.
  • EstragonEstragon Registered Users Posts: 1,616 ✭✭✭✭
    Don't know about your specific controller, but in general they can misbehave if they see just pv voltage and no/low battery voltage. A loose battery connection might do that.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • kansaskansas Solar Expert Posts: 98 ✭✭
    Interesting.  Is it possible the PV input was low enough to trigger a false LVD because the IOTA was supplying all of the charging voltage?  If so, I would think there would be many posts about it.  
    Two 140 watt Kyocera panels, wired in parallel; Ironridge top of pole mount; two 6 volt, 242 AH US batteries, wired in series; Morningstar ProStar 30 charge controller and SureSine 300 inverter; Trimetric 2025-A meter; IOTA DLS-45 charger, Honda EG3500X generator; Aermotor 702 water pumping windmill.
  • EstragonEstragon Registered Users Posts: 1,616 ✭✭✭✭
    My guess is it's only the voltage on the battery output terminal on the controller (or battery sense wire, if used) that will trigger the LVD.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • BB.BB. Super Moderators Posts: 26,872 admin
    LVD should not prevent charging... It is, generally, a voltage level that turns off (and back on) the Load Terminals. Use to control low voltage lighting, and other small(er) loads.

    There is a minimum operating voltage for (most) charge controllers... Something like below ~9.5 volts (battery terminal for 12 volt battery bank) will prevent the solar charge controller from even turning on.

    It does sound like a possible lose/bad battery connection, or possibly, a bad charge controller (time to contact MorningStar support?).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mike95490mike95490 Solar Expert Posts: 7,307 ✭✭✭✭
    i have an IOTA as a backup charger and it's never interfered with the Morningstar MPPT-60 LVD.  It's got to be some sort of wiring glitch.
    Powerfab top of pole PV mount | 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 ,

  • kansaskansas Solar Expert Posts: 98 ✭✭
     Bill - Just to be clear, the LVD function of the charge controller disconnects only the load terminals on the controller that power DC loads. The LVD does not disconnect the battery bank from the inverter if the voltage level drops below a certain set point.  To protect the battery bank from being drained, maybe completely discharged, if the inverter is accidentally left on would require a voltage controlled switch entirely separate from the charge controller. If this is correct, I've been confused about the LVD function of a charge controller as, I think, have others.  
    Two 140 watt Kyocera panels, wired in parallel; Ironridge top of pole mount; two 6 volt, 242 AH US batteries, wired in series; Morningstar ProStar 30 charge controller and SureSine 300 inverter; Trimetric 2025-A meter; IOTA DLS-45 charger, Honda EG3500X generator; Aermotor 702 water pumping windmill.
  • kansaskansas Solar Expert Posts: 98 ✭✭
    Of course most inverters have a built in LVD as well.
    Two 140 watt Kyocera panels, wired in parallel; Ironridge top of pole mount; two 6 volt, 242 AH US batteries, wired in series; Morningstar ProStar 30 charge controller and SureSine 300 inverter; Trimetric 2025-A meter; IOTA DLS-45 charger, Honda EG3500X generator; Aermotor 702 water pumping windmill.
  • BB.BB. Super Moderators Posts: 26,872 admin
    That standard inverter shutdown voltage is ~10.5 volts (for a 12 volt battery). That low of bus voltage can be damaging to the battery bank... And the inverter shutdown voltage is there to primarily protect the inverter. Remember that Power=Voltage*Current... As the voltage falls, the current must rise to support a given load--The input current can overheat the inverter's input circuitry (Power=I^2*R heating).

    Also, I believe that inverters will "brown out" the AC loads (AC voltage falls out of regulation) at or below battery cutoff voltage.

    Lead acid batteries contain almost no usable energy at 10.5 volts--It is a good voltage to use anyways. The MorningStar 300 Watt TSW 12 volt inverter, as I recall, can be programmed for 11.5 volt shutdown--Which can help prevent battery damage from "too deep" discharge.

    -Bill


    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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