battery cutoff set points

Shawn-H
Shawn-H Solar Expert Posts: 107 ✭✭
in Solar Beginners Corner #1
I'm trying not to use more than 50% DOD on my batteries. I have people in my home that are not aware of how solar works. so I do not want to lower the threshold below 11.8. The problem is is as we know while there is a load on the system the voltage will read lower than it really is so on a cloudy day if my well pump kicks on the whole system will shut down. so does anybody have any suggestions of a good place to set it so this does not happen? so I don't get called home from work again because they have no power. I have it set at 11.8 right now I'm using 2 Outback power VFX3524 in the fw-500.
100% Off-grid in the White Mountains of Arizona. 36 Kyocera 265w mounted on four DPW 9 module pole top mounts, midnite solar combiners, breakers, & lightning arresters, 1 midnight solar classic 150, & 3 classic 150 lights, 3 x 1574 AH GB Industries forklift batteries total of 4722 AH @24v. Feeding a Outback power systems FW500 with 2 x VFX 3624, with the x240. 2 Honda EU3000is gensets with the 240 combiner and control box running LP, and 1 Honda EU2000is Gas. 
System #2 is a off grid water system @ 1590w (6 Kyocera 265's) on a 6 module DPW top of pole mount. Feeding a Granfas deep well pump and pump controller at 580 feet. 2 x 2800 gallon above ground poly storage tanks, and 1 x 1200 gallon underground  cistern and a Granfas 24v booster pump feeding a 90 gallon carbon fiber pressure tank.
Vag woodstove for heat.
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,567 admin
    #2
    You could try ~11.5 volts for the cutoff... Use a Hydrometer to estimate the battery bank state of charge.

    You could also try a battery monitor (Trimetric or Victron are a good point to start looking) -- They will give readings in percent, and with the Victron, you could set an external alarm (flashing light, etc.) when the batteries are getting low--But not turn anything off.

    Tell them something like:

    >75% SOC, all is fine
    75% to 50% start cutting back on loads, especially if cloudy/winter day
    <50%, start genset. Run genset until >80% state of charge.
    <45% call you.

    There are some voltage only Battery Monitors--I am not sure how well they work (others here may have some information):

    Midnite Battery Monitor
    SmartGuage

    Those may be "good enough" for the family.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Shawn-H
    Shawn-H Solar Expert Posts: 107 ✭✭
    #3
    BB. wrote: »
    You could try ~11.5 volts for the cutoff... Use a Hydrometer to estimate the battery bank state of charge.

    You could also try a battery monitor (Trimetric or Victron are a good point to start looking) -- They will give readings in percent, and with the Victron, you could set an external alarm (flashing light, etc.) when the batteries are getting low--But not turn anything off.

    Tell them something like:

    >75% SOC, all is fine
    75% to 50% start cutting back on loads, especially if cloudy/winter day
    <50%, start genset. Run genset until >80% state of charge.
    <45% call you.

    There are some voltage only Battery Monitors--I am not sure how well they work (others here may have some information):

    Midnite Battery Monitor
    SmartGuage

    Those may be "good enough" for the family.

    -Bill
    thank you. That's a really good idea I think I'm going to copy and paste it print it and stick it on the wall I have the whizbang Jr from midnight solar it works really well. now I just have to figure out how to make it set alarm off. Lol. its my daughter I'm worried about my wife is over diligent. she freaks out at 24.4v. Lol keep trying to tell her its ok you can use the batteries that's what they're there for.
    100% Off-grid in the White Mountains of Arizona. 36 Kyocera 265w mounted on four DPW 9 module pole top mounts, midnite solar combiners, breakers, & lightning arresters, 1 midnight solar classic 150, & 3 classic 150 lights, 3 x 1574 AH GB Industries forklift batteries total of 4722 AH @24v. Feeding a Outback power systems FW500 with 2 x VFX 3624, with the x240. 2 Honda EU3000is gensets with the 240 combiner and control box running LP, and 1 Honda EU2000is Gas. 
    System #2 is a off grid water system @ 1590w (6 Kyocera 265's) on a 6 module DPW top of pole mount. Feeding a Granfas deep well pump and pump controller at 580 feet. 2 x 2800 gallon above ground poly storage tanks, and 1 x 1200 gallon underground  cistern and a Granfas 24v booster pump feeding a 90 gallon carbon fiber pressure tank.
    Vag woodstove for heat.
    Follow our journey at
    https://www.facebook.com/ShawnpHarvey
    · Share on Twitter
  • BB.
    BB. Super Moderators, Administrators Posts: 33,567 admin
    #4
    Make sure to double check everything (i.e., use a hydrometer once in a while to validate the SOC readings). Battery Monitors can "drift" at times/under some conditions.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #5
    A ew hrs in the dark may sharpen their observational skills, as to using too much power in the first place...:roll:
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
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  • Shawn-H
    Shawn-H Solar Expert Posts: 107 ✭✭
    #6
    westbranch wrote: »
    A ew hrs in the dark may sharpen their observational skills, as to using too much power in the first place...:roll:

    yes sir. I tried that but unfortunately all it did was make me sleep on the couch the wife didn't appreciate it much especially when she found out all she had to do was start the generator lol
    100% Off-grid in the White Mountains of Arizona. 36 Kyocera 265w mounted on four DPW 9 module pole top mounts, midnite solar combiners, breakers, & lightning arresters, 1 midnight solar classic 150, & 3 classic 150 lights, 3 x 1574 AH GB Industries forklift batteries total of 4722 AH @24v. Feeding a Outback power systems FW500 with 2 x VFX 3624, with the x240. 2 Honda EU3000is gensets with the 240 combiner and control box running LP, and 1 Honda EU2000is Gas. 
    System #2 is a off grid water system @ 1590w (6 Kyocera 265's) on a 6 module DPW top of pole mount. Feeding a Granfas deep well pump and pump controller at 580 feet. 2 x 2800 gallon above ground poly storage tanks, and 1 x 1200 gallon underground  cistern and a Granfas 24v booster pump feeding a 90 gallon carbon fiber pressure tank.
    Vag woodstove for heat.
    Follow our journey at
    https://www.facebook.com/ShawnpHarvey
    · Share on Twitter
  • Shawn-H
    Shawn-H Solar Expert Posts: 107 ✭✭
    #7
    BB. wrote: »
    Make sure to double check everything (i.e., use a hydrometer once in a while to validate the SOC readings). Battery Monitors can "drift" at times/under some conditions.

    -Bill

    very good advice thank you.
    100% Off-grid in the White Mountains of Arizona. 36 Kyocera 265w mounted on four DPW 9 module pole top mounts, midnite solar combiners, breakers, & lightning arresters, 1 midnight solar classic 150, & 3 classic 150 lights, 3 x 1574 AH GB Industries forklift batteries total of 4722 AH @24v. Feeding a Outback power systems FW500 with 2 x VFX 3624, with the x240. 2 Honda EU3000is gensets with the 240 combiner and control box running LP, and 1 Honda EU2000is Gas. 
    System #2 is a off grid water system @ 1590w (6 Kyocera 265's) on a 6 module DPW top of pole mount. Feeding a Granfas deep well pump and pump controller at 580 feet. 2 x 2800 gallon above ground poly storage tanks, and 1 x 1200 gallon underground  cistern and a Granfas 24v booster pump feeding a 90 gallon carbon fiber pressure tank.
    Vag woodstove for heat.
    Follow our journey at
    https://www.facebook.com/ShawnpHarvey
    · Share on Twitter

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