Generator charging my batteries

freddieoliveras
freddieoliveras Registered Users Posts: 33 ✭✭
in Off Grid Solar & Battery Systems #1
hi,
I’m planning to connect a generator (inverter) to my offgrid system, Usually at 5am my inverter shutdown because the batteries reach the 80%. I have an inverter(sigineer) and a charge controller (outback)separately. My question is:
at 5am my gen will start, but at 6:30 the sun will start charging also my batteries, is there any problem with that? Both charging the batteries at the same time? Do I have to turnoff the gen as soon the panels start charging the batteries?
thx
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,101 ✭✭✭✭✭
    #2
    Are you in the northern hemisphere? The longest day of the year was last week. If you are shutting down from a low battery now, it's only going to get worse as the days get shorter.

     Are your batteries shot?
     
    Are you under powered battery or panel wise?

    Sounds like you have other issues to correct first. You are going to burn a lot of fuel running the generator every day. A properly designed system would only need the generator on rare extended cloudy occasions, if at all.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited June 2019 #3
    The answer is its it's fine to have multiple charging sources, what you might find is the generator charging source may overwhelm the solar especially in the early hours, usually the solar will loose the battle and wait until the generator is turned off.

    The big question is what is the 80%reference too, 80% depleted or 20% depleted? Assuming 80% depleted due to inverter shut down, this may be OK or bad, depending on wether they are lead acid or lithium, so more details would help.
    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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  • freddieoliveras
    freddieoliveras Registered Users Posts: 33 ✭✭
    #4
    Batteries:AGM

    I live in the Caribbean but is the storm season we have cloudy days and also the saharan dust affect the panels.

    20%depleted

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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,101 ✭✭✭✭✭
    #5
    What is the low voltage cut off voltage set at?  80% is meaningless if not properly input into whatever battery meter you are using.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    #6
    freddieoliveras said:
    Batteries:AGM

    I live in the Caribbean but is the storm season we have cloudy days and also the saharan dust affect the panels.

    20%depleted

    If only 20% depleted then there is more capacity that could be used without harmful effects, 50% is the benchmark maximum with lead acid, trying to limit to very shallow discharge can extend life to some degree but there is a ballancing point where the value is sacrificed in preservation, batteries do die of old age as well. Perhaps 35- 40% depth-of-discharge (DOD )  would be a cost effective figure, but I have to ask, how are you determining the DOD? If by voltage alone, that is very inaccurate, if using a shunt measuring what goes in versus what goes out is a more reliable means of calculation but not perfect, especially over time as values can drift.
    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.
    · Share on Twitter

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