20ºF AGM batteries

just starting
just starting Registered Users Posts: 235 ✭✭✭
in Off Grid Solar & Battery Systems #1
So I have a 894 ah 24v bank of AGM batterys. My voltage in the am before sun has been 24.4 volts to 24.8. I use about 2-3.5 kw per night I hit float 355 days a year.. for the last two years and have olny run a gen 5 times when there is a bad day for sun. Is it common for the volts to be low because of battery temp. As soon as the sun hits the panels it goes to 25 v or above with olny 5ah in to the bank.I figure I lose about 30 percent of the capacity because of temp. In the summer it never drops below 25.1 at 55ºf battery temp.
200ah LiFePO4 24v Electrodacus Sbms40 quad breaker chest freezer to fridge- Samlex PST 1524 - Samlex pst3024  - 1hp shallow well pump-Marey 4.3 GPM on demand waterheater - mama bear Fisher wood burning stove, 30" fridgarair oven ,fridegaire dishwasher  Unique 290l stainless D.C. Fridge-unique 120l portable fridge/freezer 
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #2
    JS, what are you charging specs, that is quite a range in voltages...  you use about 2 x my overnight draw and my early morning voltages are the same day after day..., I stop getting to float about the middle of November to mid Feb, I have 1680W of PV right now, will erect final array this year, 2160W, I hope.
    How long are you in Absorb? Absorb V? Float V?
     
    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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  • just starting
    just starting Registered Users Posts: 235 ✭✭✭
    #3
    Float is 27.6 asorb is 29.5 bulk is 28.4 max asorb Is 210 min. At temp float is 28.5 asorb hits 30.5
    200ah LiFePO4 24v Electrodacus Sbms40 quad breaker chest freezer to fridge- Samlex PST 1524 - Samlex pst3024  - 1hp shallow well pump-Marey 4.3 GPM on demand waterheater - mama bear Fisher wood burning stove, 30" fridgarair oven ,fridegaire dishwasher  Unique 290l stainless D.C. Fridge-unique 120l portable fridge/freezer 
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  • just starting
    just starting Registered Users Posts: 235 ✭✭✭
    #4
    Was in float today for 7.33 min. lol.
    200ah LiFePO4 24v Electrodacus Sbms40 quad breaker chest freezer to fridge- Samlex PST 1524 - Samlex pst3024  - 1hp shallow well pump-Marey 4.3 GPM on demand waterheater - mama bear Fisher wood burning stove, 30" fridgarair oven ,fridegaire dishwasher  Unique 290l stainless D.C. Fridge-unique 120l portable fridge/freezer 
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  • just starting
    just starting Registered Users Posts: 235 ✭✭✭
    #5
    I have 6 kids so my draw constantly changes every day. I'm just trying to keep it above 24 v through winter. 60 days untill 30ºnights. I can't wait!!!
    200ah LiFePO4 24v Electrodacus Sbms40 quad breaker chest freezer to fridge- Samlex PST 1524 - Samlex pst3024  - 1hp shallow well pump-Marey 4.3 GPM on demand waterheater - mama bear Fisher wood burning stove, 30" fridgarair oven ,fridegaire dishwasher  Unique 290l stainless D.C. Fridge-unique 120l portable fridge/freezer 
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #6
    just starting said:
    So I have a 894 ah 24v bank of AGM batterys. My voltage in the am before sun has been 24.4 volts to 24.8. I use about 2-3.5 kw per night I hit float 355 days a year.. for the last two years and have olny run a gen 5 times when there is a bad day for sun. Is it common for the volts to be low because of battery temp. As soon as the sun hits the panels it goes to 25 v or above with olny 5ah in to the bank.I figure I lose about 30 percent of the capacity because of temp. In the summer it never drops below 25.1 at 55ºf battery temp.

    It's more likely that you get less sun and your evening loads aren't absorbed by running off the array, and you have a little more lighting requirements and if it's a little cold, perhaps you have a little more time with kids inside. Just a few extra loads and less available sun to the array for diverting them.
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • just starting
    just starting Registered Users Posts: 235 ✭✭✭
    #7
    My biggest load I think is a 1.5 amp 24v axial fan pushing hot air to a cold room It's like 900 watts a day can't figure a way around it this season. I wish i could add 1500 more watts and a m cl cc Then I could add more loads and have to go 48v then must be time now.
    200ah LiFePO4 24v Electrodacus Sbms40 quad breaker chest freezer to fridge- Samlex PST 1524 - Samlex pst3024  - 1hp shallow well pump-Marey 4.3 GPM on demand waterheater - mama bear Fisher wood burning stove, 30" fridgarair oven ,fridegaire dishwasher  Unique 290l stainless D.C. Fridge-unique 120l portable fridge/freezer 
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #8
    Depending on how cold the bank is, you could certainly be losing 30% of capacity. The cold wouldn't cause lower morning voltage directly, but the lower capacity and possibly higher loads will.

    For heating the cold room maybe consider using demand water heater for hydronic radiant? Moving water for heat is generally more efficient than moving air.

    I use a Rennai to heat infloor radiant. It's nice as wood stove heat rises and leaves floors cold. Radiant makes floors nice and cozy. If infloor isn't practical you could use baseboard or panel rads?
    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
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #9
    well  7.33 minutes is petty close to not getting enough charge.  Have you done any early, predawn gen charge of
    ~ 1hr to cover the morning usage and then let the PV do the lighter lifting of  declining ABSORB an then extend the Absorb by 1 hr or more? sounds like you are really close to the edge on that system capacity wise for the family as it is right now... winter sun is pretty weak
     
    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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  • just starting
    just starting Registered Users Posts: 235 ✭✭✭
    #10
    Have tried to run just twice in the am with the gen. I'm sure part of the problem is the washer running before noon and float .
    200ah LiFePO4 24v Electrodacus Sbms40 quad breaker chest freezer to fridge- Samlex PST 1524 - Samlex pst3024  - 1hp shallow well pump-Marey 4.3 GPM on demand waterheater - mama bear Fisher wood burning stove, 30" fridgarair oven ,fridegaire dishwasher  Unique 290l stainless D.C. Fridge-unique 120l portable fridge/freezer 
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  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    #11
    Suggestion:  do the wash ONLY when you run the genny...

     that way the bank gets charged and the washer doesn't draw (much, if at all) from the battery bank...
     
    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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  • just starting
    just starting Registered Users Posts: 235 ✭✭✭
    #12
    Not a bad idea I'll give that a try tomorrow morning that way by the time asorb hits the clothes will be dry on the line?
    200ah LiFePO4 24v Electrodacus Sbms40 quad breaker chest freezer to fridge- Samlex PST 1524 - Samlex pst3024  - 1hp shallow well pump-Marey 4.3 GPM on demand waterheater - mama bear Fisher wood burning stove, 30" fridgarair oven ,fridegaire dishwasher  Unique 290l stainless D.C. Fridge-unique 120l portable fridge/freezer 
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  • just starting
    just starting Registered Users Posts: 235 ✭✭✭
    edited January 2017 #13
    Ok ran genny for 1 hour or his morning I'm In float battery only took 46.2 ah and 1.29 kw changed the asorb to 270min
    200ah LiFePO4 24v Electrodacus Sbms40 quad breaker chest freezer to fridge- Samlex PST 1524 - Samlex pst3024  - 1hp shallow well pump-Marey 4.3 GPM on demand waterheater - mama bear Fisher wood burning stove, 30" fridgarair oven ,fridegaire dishwasher  Unique 290l stainless D.C. Fridge-unique 120l portable fridge/freezer 
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