Schneider sw4024 charging 24V 3.8 SimpliPhi

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I have a schneider sw4024 inverter charger that is connected to a 24v 3.8 simpliphi battery. I have all the protections in place for overvoltage charge/discharge etc.

My question is this: when I am charging my my battery via generator backup, the the charging logic starts charging the battery at 22.5 amps then when it reaches bulk at 27.2 it increases the amps to 45 for 60 min. (Voltage stays at 27.2). Is this normal? I am use to seeing a higher amperage at the beginning of the charge cycle and reducing as it finishes the bulk (at 27.2).

Any help would be appreciated.

Thank you

Comments

  • RCinFLA
    RCinFLA Solar Expert Posts: 1,484 ✭✭✭✭
    edited November 2020 #2
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    If you bulk at 22.5 amps the battery voltage will rise over time, although not dramatically on LFP batteries below 85% SOC, then fix voltage limit at some point the battery charge current must go down.   If charger current increases from 22.5 amps to 45 amps the battery voltage must continue to go up and will not be held at 27.2 volts..

    What you are saying does not make sense. 

    Check the settings and make sure you don't have some interaction with AC loads.  If you only see it on generator then there may be a problem with generator overloading.  Set your AC2 (gen) max input AC current to about 75% of generator maximum continuous amperage limit.  On inverter if AC max input is reached it will override charger settings if they are set higher then can be supported by AC input limit.
  • offgriddercritter
    offgriddercritter Registered Users Posts: 5 ✭✭
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    No it isn't anything to do with the generator overloading. Plenty of genny. I have max bulk current set at 45 amps. bulk voltage at 27.2 bulkterm voltage at 26.7 (not sure what that is).

    So when it starts charging in bulk, it charges at 22.5 amps. Even if I have charge rate set at 100%. When it goes to absorb it jumps up to 45 amps. The only thing I can think of is something wrong with the software maybe?
  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
    edited November 2020 #4
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    There must be something wrong with the settings, the bulk voltage should be the same as the absorption, absorption time should be set for 6 minutes, according to SimpliPhi's recomendations for Schneider equipment. An increase in current on transition to absorption would indicate the absorptio voltage is set at a higher value than bulk.

    Did you install the equipment  and program the inverter yourself?  Is there similtanious solar input  and if so are the charge controller settings the same as the SW? 
    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.
  • offgriddercritter
    offgriddercritter Registered Users Posts: 5 ✭✭
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    Yes I installed it myself. And yes there is simultaneous solar input and the cc setting are the same as sw. I spoke with simpliphi and they could not figure it out. Schneider is a dead end as well. If the absorption voltage is set higher than bulk, how do I change that? 
  • offgriddercritter
    offgriddercritter Registered Users Posts: 5 ✭✭
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    I just changed the charger settings to custom and input the correct parameters and it works fine like that. There is no option to change the absorb voltage on the lithium ion setting. What is up with that?
  • BB.
    BB. Super Moderators, Administrators Posts: 33,442 admin
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    Generally there is only "bulk" and "float" stages for Lithium batteries... I.e., the charging stops when the battery reaches 4.15 volts (or whatever) per cell. LiFePO4 batteries are "full" when the charging setpoint is reached.

    Lead Acid batteries need to hold the charging setpoint for 2-6 hours or so (deeper cycle, longer absorb cycle) to fully recharge. Lead Acid batteries are only ~80-90% full when the charging setpoint voltage is reached (depends on charging current, etc.)

    Anyway--No expert--But that is how I understand the reasoning.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • mcgivor
    mcgivor Solar Expert Posts: 3,854 ✭✭✭✭✭✭
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    Seems SimpliPhi's recomendations have changed since I installed my system in 2018, they have decreased the bulk/absorb target voltage, was previously 28V, as well as increased the absorption time from 6 minutes to 2 hours. Are these the settings that are being used? 

    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.
  • offgriddercritter
    offgriddercritter Registered Users Posts: 5 ✭✭
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    No, when I was on the phone with simpliphi, ( and also stated in the new simpliphi iq training) they suggested I put the bulk/absorption voltage at 28 for 6 minutes. And this will be updated shortly on there website. They said only to put it at 27.2 for 60 min if your cc or charger can't go as low as 6 min. Other than that, the settings are the same. I just looked through the firmware updates for schneider and it looks like there was a firmware update for lithium batteries back in 2018. The csw was purchased in 2019 so its possible I need to update it.