Battery Charging

kelperis
kelperis Registered Users Posts: 45 ✭✭
in General Solar Power Topics #1
I am using 200ah 12volt batteries in parallel. I am advised to try to keep them with the highest SOC as possible and whenever possible, to charge with low amperage. I have three PV banks that should provide 30 amps, and I have an IOTA charger that can charge up to 75amps depending on the type of charge the battery needs.

my question is...should I let the PV’s handle the charging/load and only have the IOTA handle the charging/load at night, or if the batteries get overly depleted. What happens if all the chargers/charge controllers are on at the same time? What would be great is if the charging sources could be prioritized, PV’s first, then the charger if needed to handle the load and/or charging needs. Anyone else do this?
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  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    #2
    How do you power the Iota charger ?

    How many 12V batteries do you have in parallel

    I manage my battery bank primarily with solar, and generator only when the sun don't shine
    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 ,

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  • kelperis
    kelperis Registered Users Posts: 45 ✭✭
    edited November 2018 #3
    The IOTA charger is powered by MAINS, or by my LP generator if MAINS are down. I had only planned on running the IOTA at night to make sure I start each day 100% SOC. I will have around 90-12oamps coming in on three charge/controllers. I am only moving critical circuits to full time solar, so I still have MAINS, a hybrid setup I know. I have six of the batteries for a total of 1200ah.
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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #4
    What is the system for if the batteries are charged all the time never being cycled, just curious.
    1500W, 6× Schutten 250W Poly panels , Schneider MPPT 60 150 CC, Schneider SW 2524 inverter, 400Ah LFP 24V nominal battery with Battery Bodyguard BMS 
    Second system 1890W  3 × 300W No name brand poly, 3×330 Sunsolar Poly panels, Morningstar TS 60 PWM controller, no name 2000W inverter 400Ah LFP 24V nominal battery with Daly BMS, used for water pumping and day time air conditioning.  
    5Kw Yanmar clone single cylinder air cooled diesel generator for rare emergency charging and welding.
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  • kelperis
    kelperis Registered Users Posts: 45 ✭✭
    #5
    It is a hybrid really. All of my critical requirements are on solar, except for the 220AC items (which I bkup with reduced function alternatives.) This allows me to reduce my monthly power bill just enough to recoup my investment. It also eliminates the need for a larger BKUP/recovery generator, which I need for medical reasons. The reason I am trying to keep discharge percentage low is to help ensure the longest possible battery(12volt GEL 200ah) life. I only need about seven years for the system to pay for itself, and I am hoping for more. The electronics should last longer, and I have redundant equipment limited to no more than 50%, allowing me to keep running if I have an equipment failure. I plan to just have the charger on at night to handle the nighttime load, and to top off the batteries if needed, but was wondering about all the multiple charging sources, hence the original question. Trying to make it as automated as possible.
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  • Estragon
    Estragon Registered Users Posts: 4,496 ✭✭✭✭✭
    #6
    I never use my Iota chargers except for bulk generator charging.  They are good for this purpose, but IIRC have pretty limited adjustment for voltages, etc.

    In your application, I would use pv controllers to float the bank at lowish voltage.  In an outage, I would run the bank down to a 40-60% state of charge (assuming available solar vs loads gets it that far down), then recharge with generator/Iota up to ~85% SOC and let solar finish.  If outages are common, I'd keep discharge closer to 50-60%.  If less common, I'd go deeper on the assumption the bank will die of old age before it dies from cycling anyway.

    With 6 batteries in parallel, you'll want to keep an eye on individual states of charge, as overall SOC could hide individual battery issues.
    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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  • kelperis
    kelperis Registered Users Posts: 45 ✭✭
    #7
    Thanks for the advice. I will manually make this happen until I can figure out the pattern using the PV’s.
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